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'11-.“ ‘3‘:’1"“‘,L1II‘ 1.45116”!!sz ,‘1'131‘1‘1: 13,1, . 4 ,4 w. .1. ~ , ‘1, , 1113;3'134 11.1»qu $1.31,“, 41,7 1,1,,..:1,,,.,1 ., 41,113 445 1”,. , 31115114, 1 .1 . 3'1“..“,3 "1 1 , ‘L‘ b‘IL‘itm‘i‘n‘xu,‘ ‘13“: ‘1“ 1,. ~ ‘ “ “131931“ 1:1.‘4'1‘ '71-? -‘!.1‘-‘l“‘ “1"34111 'v"I"4‘};“1‘3‘5"1‘1‘:d‘131,;‘,.~“1“1‘1'1 L, «1,1,1 444;, 1,4, , ‘11.. ' ‘31“,1‘«;v':'::_11“1’- 4‘414 ' ., , 41:11,! 14:14,”. 1 1‘.‘ ‘ ‘ “‘1",,1,1‘:],l | ‘ 4119‘ 1 '. ‘1. '7 ".11 1113‘; ‘11-. “:5 . 01,1. . 3‘ I '44.. , 11,.“ :131‘13'1. ‘ 1 L‘l‘ V” 3241‘ 1,? 1‘3 4,:,',“',1 11 1" . . .1...1 ”1‘3; . ‘. t 1:1“.1 . T1131 E‘SZIS This is to certify that the thesis entitled MECHANICAL BEHAVIOR OF FIBROUS ORGANIC SOILS presented by Anwar S. Khattak has been accepted towards fulfillment of the requirements for the PhD degree in Civil Engineering Major professor Date Qmfit. C'l won‘t 0-7639 MECHANICAL BEHAVIOR OF FIBROUS ORGANIC SOILS By Anwar S. Khattak A DISSERTATION Submitted to Michigan State University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Department of Civil Engineering 1978 6/0377] ABSTRACT MECHANICAL BEHAVIOR OF FIBROUS ORGANIC SOILS By Anwar S. Khattak It has been common practice for engineers to avoid organic soil deposits when constructing building foundations and highway embankments. Lack of information on the mechanical behavior of these soils and the potential for decomposition have been the major reasons. This study has been directed to the influence which organic fibers have on the stress-deformation and strength behavior of a model soil prepared from kaolinite and cellulose pulp fibers. Experimental work has included compression tests to evaluate the compressibility, direct shear and triaxial tests to observe the stress-strain response and to measure the shear strength parameters. Various combinations of kaolinite and fiber were studied so as to encompass the full range of possible mechanical behavior. To pro- vide data for comparison, compression and shear strength tests on kaolinite and fiber samples have been included. Physical properties of both clay and pulp fibers were determined prior to beginning the test program. Methods available from the pulp and paper industry were adopted for measurements of a weighted average fiber length. Surface area of fiber per gram of dry material was determined using methods Anwar S. Khattak employed by soil scientists. The porous structure common to cellulose fibers was observed with the help of a scanning electron microscope. The model soil can be considered to be a skeleton of clay par- ticles and fibers enclosing both macro- and microvoids. Air and/or water fill the voids. When the model soil is subjected to an external load, compression of the sample pccurs due to l) compression of the solid matter, 2) compression of the gas and 3) drainage of water from the sample. Using compressive loads ranging from about 2 up to 350 kg/cmz, the soil compressibility was observed in terms of change in void ratio for increasing stresses. A plot of void ratio versus log- arithm of stress gives a linear curve which is typical for kaolinite. The kaolinite/fiber mixtures show a nonlinear relationship. The com- pression index or slope of these curves is a function of the soil organic content and the stress level. An immediate practical result concerns use of the compression index on field projects and the rela- tionship it has to organic content and stress level. Placement of normal or shear loads on the model soil produces first an elastic compression or displacement, and when the strength of the material is reached a compressive rupture or excessive shear displacement. The shear displacement results primarily from slip- page between particles. Direct shear tests conducted on fiber samples showed that shear resistance continued to increase with shear dis- placement up to the limits of the test equipment. Shear resistance also increased with increase in normal stress suggesting a frictional type behavior. Triaxial tests on cylindrical samples included both drained (5T5) and consolidated-undrained tests (CTU) on kaolinite, kaolinite/fiber mixtures, and all fiber samples. For undrained tests Anwar S. Khattak on high fiber content samples excess pore pressures reached values equal to cell pressures at about l5+ percent axial strain. The stress difference continued to increase raising questions as to what stage of the test should be defined as failure. Use of the peak stress dif- ference and/or 20 percent axial strain gave shear strength parameters (¢') which increased from 20 degrees for kaolinte to more than 80 de- grees for all fiber samples. A new failure criterion, based on the peak value of the stress path defined by the maximum ratio of shear stress to effective normal stress, gave lower values of ¢'- Consoli- dated-drained tests and failure based on 20 percent axial strain gave the lowest ¢' values which ranged from 20 degrees for kaolinite up to 31 degrees for all fiber samples. Availability of field data for an experimental slope failure in a fibrous papermill sludge with properties similar to the kaolinite/ fiber mixtures permitted recomputation of the factor of safety. Use of ¢' given by the consolidated-undrained tests and failure defined by the peak stress difference and/or 20 percent axial strain gave a factor of safety close to unity. This agreement with field behavior suggests that the shear strength parameter obtained from the CTU'test appears to be best suited for field analysis problems relative to organic soils. ACKNOWLEDGMENTS The writer wishes to express his appreciation to his major professor, Dr. 0. B. Andersland, Professor of Civil Engineering, for his encouragement, guidance and aid throughout the writer's doctoral studies. The writer wishes to acknowledge his gratitude to the other members of the doctoral comittee: Dr. G. Y. Baladi, Assistant Professor of Civil Engineering; Dr. N. A. Bradley, Professor of Civil Engineering; Dr. M. M. Mortland, Professor of Soil Science and Dr. R. J. Kunze, Professor of Soil Science. The writer also wishes to express his appreciation to his colleague R. w. Lentz for his interest and suggestions. Thanks are also extended to the National Science Foundation, the National Council of the Paper Industry for Air and Stream Improvement, and the Division of Engineering Research at Michigan State University for the financial assistance which made this research possible. ii TABLE OF CONTENTS Page List of Tables ......................... vi List of Figures ........................ XI LTSt of Symbols ......................... xvii CHAPTER I INTRODUCTION .................... 1 II LITERATURE REVIEW .................. 4 2.] Organic Soils ................. 4 2.l.l Natural Deposits ............. 4 2.1.2 Landfills ................ 6 2.2 Physical Properties of Organic Soils ...... 7 2.2.l Description and Structure ........ 7 2.2.2 Density ................. 10 2.2.3 Swelling Properties ........... 13 2.3 Surface Area Determination of Small Particles. . 15 2.3.l Adsorption ............... 15 2.3.2 The Solid-Gas Interface ......... 17 2.3.3 The Langmuir Equation .......... 19 2.3.4 The B.E.T. Equation ........... 25 2.4 Compressibility of Organic Soils ........ 32 2.4.1 Consolidation Behavior ......... 32 2.4.2 Compressibility of Solids ........ 38 2.5 Shear Strength of Organic Soils ........ 40 2.5.1 Stress-Strain Behavior ......... 40 2.5.2 Failure Conditions ........... 42 2.5.3 Strength of Porous Materials ...... 47 III LABORATORY EQUIPMENT AND TEST PROCEDURES 50 3.l Physical Properties of Pulp Fibers ....... 50 3.l.l Weighted Average Fiber Length ...... 50 3.l.2 Specific Gravity ............ 53 iii CHAPTER IV Page 3.l.3 Fiber Particle Surface Area ....... 54 3.2 Compression Tests ............... 55 3.2.l Compression Test Cylinder ........ 55 3.2.2 Sample Preparation ........... 55 3.2.3 Test Procedure ............. 58 3.3 Direct Shear Tests ............... 58 3.3.l Shear Box ................ 59 3.3.2 Sample Preparation ........... 59 3.3.3 Test Procedure ............. 50 3.4 Triaxial Compression Tests ........... 51 3.4.l Triaxial Equipment ........... 51 3.4.2 Sample Preparation ........... 53 3.4.3 Consolidated-Undrained Tests ...... 64 3.4.4 Consolidated Drained Test ........ 55 EXPERIMENTAL RESULTS ................ 66 4.1 Physical Properties of the Test Materials . . . 66 4.l.l Atterberg Limits and Particle Size of Kaolinite ................ 55 4.l.2 Weighted Average Fiber Length ...... 59 4.l.3 Specific Gravity of Pulp Fiber ..... 76 4.l.4 Surface Area of Pulp Fiber ....... 75 4.2 Compression Tests ............... 83 4.2.1 ~,1<._ao1,i_ni_te ,. _- ............... 83 4.2.2 Kaolinite-Fiber Mixtures ........ 85 4.2.3 Fiber Samples . . . .' .......... 85 4.3 Direct Shear Tests ............... 9] 4.3.1 Saturated Fiber ............. 9‘ 4.3.2 Dry Fiber ................ 95 4.4 Triaxial Compression Tests ........... IO] 4.4.l Kaolinite ................ 101 4.4.2 Kaolinite/Fiber Mixtures ........ %?2 4.4.3 Fiber Samples .............. iv CHAPTER V VI DISCUSSION AND INTERPRETATION OF RESULTS ....... 5.1 Physical Properties ............... 5.l.l Fiber Size, Shape, and Structure ..... 5.l.2 Kaolinite/Fiber Mixtures ......... 5.2 Compressibility of Kaolinite/Fiber Mixtures . . . 5.2.l One-Dimensional Compression ....... 5.2.2 Triaxial Consolidation .......... 5.3 Shear Strength of Kaolinite/Fiber Mixtures 5.3.1 Direct Shear Study ............ 5.3.2 Triaxial Compression ........... 5.3.2.1 Organic Versus Inorganic Soils. . 5.3.2.2 Consolidated Undrained Tests 5.3.2.3 Consolidated Drained Tests 5.3.3 Shear Strength Parameters ' and c' 5.4 Implications for Stability Problems ....... 5.4.1 Settlement ................ 5.4.2 Stability ................ SUMMARY AND CONCLUSIONS ............... 6.1 Physical Properties ............... 6.2 Compressibility of Kaolinite/Fiber Mixtures . . 6.3 Shear Strength of Kaolinite/Fiber Mixtures BIBLIOGRAPHY .......................... APPENDICES UOW> Physical Properties of Kaolinite and Fiber ...... Compression Test Data ................ Direct Shear Test Data ................ Triaxial Test Data .................. Page 126 126 126 131 133 134 144 145 145 158 158 161 173 179 182 184 185 191 191 192 193 200 200 208 215 243 TABLE bk-D-NN ##h-Pb-b-f-‘t co {OCDNOSU'l-h >3>3>> th LIST OF TABLES Densities of Cellulose Fibers in Various Bouyancy Agencts (After Hermans, 1949) ............. Compressibility Constants (After Skempton, 1961) Compressibility Constants (After Scott, 1963) ..... Fiber Length Classification .............. Weight of Fibers Retained on Four U.S. Standard Sieves. Chemical Agents Used for Different Water Vapor Pressures ....................... Tabulated Values for the B.E.T. Equation ....... B.E.T. Adsorption Isotherm Data ............ Summary of Compression Test Data ........... Summary of Direct Shear Test Results ......... Summary of Triaxial Test Results ........... Summary of Pore Pressure Coefficients A and B A Summary of Shear Strength Parameters ........ Tabulated Values for the Slope Stability Analysis Using Janbu's Method (1954, 1957) ........... Liquid Limit Determination, Kaolinite ......... Plastic Limit Determination, Kaolinite ........ Hydrometer Analysis for Kaolinite ........... Specific Gravity of Pulp Fiber Using Water as the Displacement Medium .................. Data for Determination of Specific Surface Area, Pulp Fiber ., ..................... Page 12 38 39 70 71 77 81 82 99 124 183 190 200 201 202 203 TABLE A.6 WWW) \lmmth-J d hLON .10 .11 .12 ('3 O O C") O O O O O ('3 O O ('5 co co W 03 O . 5 O O 0 0 O C 0 0'1 .13 O .14 Page One-Point Calculation for Specific Surface Area . . . 205 Consolidation Data for a Kaolinite Triaxial Test Sample ..................... 207 Consolidation Data for a Fiber Triaxial Test Sample . 207 Compression Test Data, Sample C1 .......... 208 Compression Test Data, Sample C2 .......... 209 Compression Test Data Sample, C3 .......... 210 Compression Test Data, Sample C4 .......... 211 Compression Test Data, Sample C5 .......... 212 Compression Test Data, Sample C6 .......... 213 Compression Test Data, Sample C7 .......... 214 Direct Shear Test Data, Sample 81 .......... 215 Direct Shear Test Data, Sample 32 .......... 217 Direct Shear Test Data, Sample 83 .......... 219 Direct Shear Test Data, Sample S4 .......... 221 Direct Shear Test Data, Sample 55 .......... 222 Direct Shear Test Data, Sample S6 .......... 223 Direct Shear Test Data, Sample S7 .......... 224 Direct Shear Test Data, Sample S8 .......... 225 Direct Shear Test Data, Sample 59 .......... 225 Direct Shear Test Data, Sample 510 ......... 227 Direct Shear Test Data, Sample 811 ......... 228 Direct Shear Test Data, Sample 512 ......... 229 Direct Shear Test Data, Sample 513 ......... 230 Direct Shear Test Data, Sample 314 ......... 231 Direct Shear Test Data, Sample 515 ......... 232 vii TABLE .16 O .17 .18 .19 .20 .21 .22 .23 .24 .25 UUUUUUOOOOOOOOO #005) C3 \1 CDC to .10 Direct Direct Direct Direct Direct Direct Direct Direct Direct Shear Shear Shear Shear Shear Shear Shear Shear Shear Test Test Test Test Test Test Test Test Test Data, Data, Data, Data, Data, Data, Data, Data, Data, Direct Shear Test Data, Sample Sample Sample Sample Sample Sample .......... Sample Sample Sample Sample 525 .......... Triaxial Test Triaxial Test Triaxial Test Triaxial Test Triaxial Test Triaxial Test Triaxial Test Triaxial Test Triaxial Test Triaxial Test Fiber by Triaxial Test Fiber by Triaxial Test Fiber by Triaxial Test Fiber by Volume Volume Volume Volume Data, Sample CU-l Kaolinite Data, Sample CU-2, Kaolinite ...... Data. Data, Data, Data, Data, Data, Data, Data, Data, Data, Data, Sample Sample Sample Sample Sample Sample Sample CU-3 Kaolinite CU-4 Kaolinite CU-5 Kao1inite CU-6 Kaolinite CU-7 Kaolinite CU-8 Kaolinite CU-9 Kaolinite ...... CU-FC1 75% Kaolinite/25% OOOOOOOOOOOOOOOOOOO OOOOOOOOOOOOOOOOOOO OOOOOOOOOOOOOOOOOOO Page 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 TABLE Page D.14 Triaxia1 Test Data, Sample CU-CFl 54% Fiber/46% Kaolinite by Volume ................. 255 D.15 Triaxial Test Data, Sample CU-CFZ 54% Fiber/46% Kaolinite by Volume ................. 257 D.16 Triaxia1 Test Data, Sample CU-CF3 54% Fiber/46% Kaolinite by Volume ................. 258 D.17 Triaxial Test Data, Sample CU-CF4 54% Fiber/46% Kaolinite by Volume ................. 259 0.18 Triaxial Test Data, Sample CU-CFS 54% Fiber/46% Kaolinite by Volume ................. 259 D.19 Triaxia1 Test Data, Sample CU-CF6 54% Fibers/46% Kaolinite by Volume ................. 250 D.20 Triaxial Test Data, Sample CU-CF7 54% Fibers/46% Kaolinite by Volume ................. 250 0.21 Triaxia1 Test Data, Sample CD-FCl 25% Fiber/75% Kaolinite by Volume ................. 251 0.22 Triaxial Test Data, Sample CD-FC2 25% Fiber/75% Kaolinite by Volume ................. 252 D.23 Triaxial Test Data, Sample CD-FC3 25% Fibers/75% Kaolinite by Volume ................. 253 D.24 Triaxial Test Data, Sample CD-CFl 54% Fiber/46% Kaolinite by Volume ................. 254 0.25 Triaxia1 Test Data, Sample CD-CF2 54% Fiber/46% Kaolinite by Volume ................. 265 D.26 Triaxia1 Test Data, Sample CD-CF3 54% Fiber/46% Kaolinite by Volume ................. 255 0.27 Triaxial Test Data, Sample CD-Fl A11 Fiber ..... 267 0.28 Triaxia1 Test Data, Sample CD-F2 All Fiber ..... 268 0.29 Triaxia1 Test Data, Samp1e CD-F3 All Fiber ..... 269 0.30 Triaxial Test Data, Sample CD-F4 All Fiber ..... 270 0.31 Triaxia1 Test Data, Samp1e CD-FS All Fiber ..... 271 0.32 Triaxia1 Test Data, Samp1e CD-F6 A11 Fiber ..... 272 ix TABLE Page 0.33 Triaxial Test Data, Samp1e CU-Fl All Fibers ..... 273 D.34 Triaxial Test Data, Samp1e CU-F2 A11 Fibers ...... 274 0.35 Triaxial Test Data, Samp1e CU-F3 A11 Fibers ..... 275 D.36 Triaxial Test Data, Samp1e CU-F4 All Fibers ..... 276 0.37 Triaxial Test Data, Samp1e CU-F5 A11 Fibers ..... 277 D.38 Triaxial Test Data, Samp1e CU-F6 A11 Fibers ..... 278 0.39 Triaxia1 Test Data, Sample CU-F7 A11 Fibers ..... 279 FIGURE 2 4:. #h-h-b-h-b-b .1 .3a .3b .3c .3d LIST OF FIGURES Repeating celluboise unit of cellulose (White, Handler and Smith, 1964) .............. Diagrammatic representation of the association of molecular cellulose strands showing the approcimate cross-sectional area (after Denlin, 1966) ...... Compressibility tests on Quartzitic sandstone and Vermont marble (after Zismann, 1933 and Bridgman, 1928) ........................ (a) Mohr envelope (b) Relation between Mohr stress circles and Mohr-Coulomb failure criterion ..... Stress circle at failure and four possible shear strengths (after Whitman, 1960) ........... Triaxial test on Marble (after Von Karman, 1911) . . Sectional view of the Compression Test Cylinder Triaxia1 equipment ................. Water content vs. number of blows for Kaolinite Grain size distribution curve for Kaolinite ..... Projected fiber lengths, No. 14 sieve size ..... Projected fiber lengths, No. 30 sieve size ..... Projected fiber lengths, No. 50 sieve size ..... Projected fiber lengths, No. 100 sieve size Adsorption isotherm of water on pulp fiber (cellulose) .................... B.E.T. Adsorption isotherm of water of pulp fiber Effective normal stress (Natural and logarithmic scale) vs. void ratio curves for Kaolinite samples . xi Page 36 44 46 48 57 62 67 68 72 73 74 75 79 80 85 FIGURE 4.7 4.8 4.9 Effective normal stress (Natural and logarithmic scale) vs. void ratio curves for 54% fibers/46% Kaolinite samples (by volume) ............ Effective normal stress (Natural and logarithmic scale) vs. void ratio curves for 25% fibers/75% Kaolinite samples (by volume) ............ Effective normal stress (Natural and logarithmic scale) vs. void ratio curves for all fiber samples Typical Shear displacement vs. Shear stress and Vertical displacement curves for saturated fiber samples ....................... Shear displacement vs. Shear stress and Vertical displacement curves caused by two cycles of loading and unloading a fiber sample ............. Consolidation pressure vs. final water contents for saturated fiber samples ............... Consolidation pressure vs. Void ratio curves for saturated and dry powdered fiber samples ...... Typical Shear displacement vs. Shear stress and Vertical displacement curves for dry powdered fiber samples ....................... Shear displacement vs. Shear stress and Vertical displacement curves for an oven-dried fiber sample Strain at failure vs. Consolidation pressure for Kaolinite samples .................. Consolidation pressure vs. final water contents for Kaolinite samples ................ Axial strain vs. effective deviator stress, pore pressure and pore pressure coefficient, A, curves for Kaolinite sample CU-3. . . ............. Axial strain vs. effective deviation stress pore pressure and pore pressure coefficient, A, curves for Kaolinite sample CU-7 ............. Consolidation pressure vs. Water content curve for 54% fibers/46% Kaolinite samples (by volume) xii Page 87 88 89 92 93 94 96 97 98 102 103 104 105 108 EIGURE 4.21 5.1 5.2 Page Typical results from a normally consolidated undrained triaxial test on 54% fiber/46% Kaolinite (by volume). (a) Deviator stress (b) pore pressure change (c) Change in paramater A ..................... Typical results from a drained triaxial test on 54% fiber/46% Kaolinite (by volume). (a) Deviator stress (b) Volume change ................... Consolidation pressure vs. Water content for 25% fibers and 75% Kaolinite samples (by volume) ......... Typical results from a normally consolidated undrained triaxial test on 25% fiber/75% Kaolinite (by volume) (a) Deviator stress (b) Pore pressure change (c) Change in parameter ...................... Typical results from a drained triaxial test on 25% fiber/75% Kaolinite (by volume). (a) Deviator stress (0) Volume change ................... Consolidation pressure vs. Water content for fiber samples ........................ Typical results from a normally consolidated undrained triaxial test on a fiber sample. (a) Deviator stress (b) Pore pressure change (c) Change in parameter A. . . Typical results from a drained traixial test on a fiber sample. (a) Deviator stress (b) Volume change. . Typical results from a drained triaxial test on a fiber sample consolidated to a low pressure. (a) Deviator stress (b) Volume change ........... Relationship between volume change and VTime for a Kaolinite, 54% fiber/46% clay, 25% fiber/75% clay and fiber sample under all around pressure (radial and end drainage) ................... Influence of organic (fiber) content on the pore pressure parameter A at failure in triaxial tests . . . (a) 2000 magnification of the cross section of a single pulp fiber (b) 120 magnification of several pulp fibers ........................ Surface characteristics of cellulose pulp fibers, 2000 magnification .................. 109 110 111 112 113 116 117 118 119 121 125 127 128 FIGURE 5.3 5.4 Fiber-clay particle size comparisons, 1000 magnification_+.... . ... . Scanning electron microscope photographs, 1000 magnification. (a) Cellulose pulp fiber (b) Kao- linite particles .................. Final water contents after one-dimensional loading to about 360 kg/cm2 for kaolinite, two kaolinite/ fiber mixtures, and fiber samples ......... Effective normal stress vs. Void ratio curves for all fiber, 25% fiber/75% Kaolinite, 54% fibers/46% Kaolinite, and all Kaolinite samples ....... Effective normal stress vs. Void ratio plot for the Kaolinite/fiber samples near the common point of interaction of all tilted curves ......... Effective normal stress vs. void ratio curves for the - Kaolinite/fiber samples on a semi-logarithm scale . Pressure vs. Coefficient of Volume compressibility for kaolinite, two kaolinite/fiber mixtures, and fiber samples ................... Consolidation pressure vs. % water content for kaolinite/fiber samples .............. Direct shear stress displacement curves for con- solidated saturated fiber samples ......... Direct shear-test samples after completion of the tests .............. , ....... , Schematic of the failure zone in a fiber sample after being subjected to a direct shear test Shear displacement vs. Shear stress and Vertical displacement curves showing the effect of water absorption during the test by saturated fiber samples ...................... Direct shear stress displacement curves for con- solidated dry powdered fiber samples ....... Shear displacement vs. Shear stress and Vertical displacement curves for dry and saturated fiber samples showing the effect of water ....... xiv Page 129 130 135 137 138 139 142 146 148 152 153 154 FIGURE 5.17 5.18 5.19 Summary of direct shear data for fully saturated fully saturated full-lenth fiber samples ...... Summary of direct shear data for dry powdered fiber samples ................... Comparison of direct shear data for fully saturated fiber samples at 10 and 20 percent displacement strain ....................... (a) Saturated inorganic soil fabric (b) Idealized saturated organic soil ............... Summary of consolidated undrained triaxial test data for kaolinite ................. Summary of consolidated undrained triaxial data for 25% fiber/75% kaolinite samples (by volume) Summary of consolidated undrained triaxial data for 54% fiber/46% clay (by volume) mixtures . . . . Summary of consolidated undrained traixial data for all fiber samples .................. Stress paths for samples with (a) all fibers and (b) 54% fibers/46% Kaolinite (by volume) ...... (a) Clay plates at low consolidation pressure (b) Clay plates at relatively higher consolidation pressure (c) Cross section of fibers at low strain and (d) at higher strain .............. Summary of consolidated drained triaxial data for 25% fiber/75% Kaolinite (by volume) mixtures) Summary of consolidated drained triaxial data for 54% fiber/46% Kaolinite (by volume) mixtures . . . . Summary of consolidated drained triaxial data for all fiber samples ................. Stress-strain curves for samples with varying Kaolinite/fiber compositions showing the change in failure mechanisms for drained conditions ..... Triaxial data for consolidated undrained tests on samples with 54% fiber/46% clay by volume ..... Fiber (organic) content vs. shear strength parameter ¢', consolidated undrained and consolidated drained Triaxial tests ................... XV Page 155 156 157 159 163 164 166 167 170 172 174 176 177 178 180 181 FIGURE 5.33 5.34 A.1 Page Cross section of the 1:8 slope, before and after failure, with slice locations shown for the sta- bility analysis (after Charlie and Andersland, 1975). 186 Estimated pore pressures near the exposed sludge surface based on field (Charlie and Andersland, 1975) and laboratory (Laza, 1971) data ....... 188 One point B.E.T. plot ................ 209 xvi oJ OJ :3 C) m z 1'0 k1 LIST OF SYMBOLS Pore pressure coefficient Pore pressure coefficient at failure Contact area Unit contact area Cross-sectional area of a water molecule Pore pressure coefficient. Absorption coefficient Constant Compressibility of solids Volume compressibility Shear strength parameter (cohesion) Volume compressibility of solids. Coefficient of consolidation Particle density HWater density at different temperatures Void ratio Initial void ratio Safety factor Specific gravity Hydrostatic pressure head Boltzman constant xvii S, S] t1: tzooot Line through 5 versus q Weighted average length Length Molecular weight Mass Avogadro's number Number Pressure Pressure, effective stress basis Saturation pressure 1/2(61 + 83) Heat quantity 1/2(51 - 63) Molar gas constant Number of gas molecules Absolute temperature Adsorption time Pore pressure Pore pressure, at failure Volume Initial volume volume absorbed Monolayer capacity Total weight = Weight xviii ws’w’w’ SW 0. 0!. ’ o 0'" a C72: 0') Tff Weight Weight of moisture Condensation coefficient Inclination angle of force Slope of 5 versus q Constant Compressibility of solids Unit Weight, soil solids Unit weight, water Unit weight, soil solids at atmospheric pressure Pore pressure increment Pressure increment, effective stress basis Volume change Change in height Slice width Constant Fraction of surface area Rate at which molecules strike a surface Rate of departure of molecules Normal stress Effective normal stress Normal stress on failure surface at failure Principal stresses Shear stress on failure surface at failure Shear stress on the plane of maximum obliquity xix th Tmf rd '6 en Shear stress on the plane of tangency - Maximum shear stress at failure Time a molecule stays on surface Intrinsic line Failure envelope Shear strength parameter, based on effective stresses Inclination of intrinsic line XX CHAPTER I INTRODUCTION One of the major problems facing the industrialized nations is the need for better utilization of land. In certain areas constructed facilities must now be designed for placement on organic soil deposits. Questions arise immediately as to how much settlement may occur and will the foundation be stable. In other areas shipping channels must be excavated through thick organic soil sediments. There is concern over stability of the side slopes as ships traverse the channel. Paper— mill operations are finding that their high ash sludge deposits occupy expensive land area which they now wish to use for other purposes. These sludge deposits are similar to organic soils and consist primarily of kaolinite and organic material. Questions arise as to compressi- bility, shear strength, and the potential for future decomposition of the organic component. This project is concerned with the mechanical behavior of these fibrous organic soils. Much of the experimental work reported in the literature has been done on samples of peat, muskeg, or high ash papermill sludges. The investigators have been somewhat limited as to how they could vary the organic content, being restricted to field samples. In some cases organic content was not included with data reported on the mechanical behavior. Research on high ash papermill sludge showed that organic content had a very significant effect on both consolidation behavior 1 and shear strength. To provide an overall picture of how the organic component influences the mechanical behavior, it was decided to prepare a model organic soil from kaolinite and pulp fibers. The fibers, almost pure cellulose, are produced from soft or hard wood for the manufacture of paper. The physical nature of these cellulose fibers depend upon the type of wood (hard or soft) from which fibers are extracted. Cellu- lose fibers are by nature hydrophyllic and therefore highly compressible. The weighted average fiber length and fiber particle specific surface area were measured using special tests common to paper technol— ogiStsL and soil scientists, respectively. Other physical properties of the pulp fiber and kaolinite were determined by standard tests. The kaolinite-fiber combinations resembled organic soils with high compressibility and low shear strength at the usual high water contents. The model soil mixtures were in most cases prepared by combining dry fluffed fiber with dry clay in the selected proportions and combining them with water. Stress history was accounted for during drainage to insure normal consolidation of triaxial samples. Compressibility of the model soil was observed using a special compression cylinder. Triaxia1 tests, both consolidated undrained and drained conditions, were run to determine the stress-strain behavior and shear strength parameters. Details are given in the appropriate sections. The experimental results confirm that compressibility is highly dependent on organic content and stress level. For large stress changes the compression index is not constant as compared to kaolinite. Consolidation tests on samples from field sites is an appropriate means to determine the consolidation parameters for use in prediction of field settlements. Strength tests on organic soils can be misleading. For undrained tests on high fiber content samples, excess pore pressures reached values equal to cell pressures at about 15 percent axial strain. The stress difference continued to increase raising questions as to what stage in the triaxial test should be considered failure. Use of the peak stress difference and/or 20 percent axial strain gave shear stnength parameters (¢') which increased from 20 degrees for kaolinite to over 80 degrees for all fiber samples. A new failure criterion, based on the peak values of the stress path defined by the maximum ratio of shear stress to effective normal stress gave lower values of ¢'. Consoli- dated-drained tests and failure based on 20 percent axial strain gave the lowest 6' values which Fanged from 20 degrees for kaolinite up to 31 degrees for all fiber samples. These experimental results did not answer the question as to which shear strength parameters are most suitable for field problems. Availability of field data on an experimental slope failure in a fib- rous papermill sludge which is similar to the kaolinite/fiber mixtures permitted recomputation of the factor of safety. Using ¢' from the consolidated-undrained test results corresponding to the organic con- tent of the papermill sludge and extrapolation of field pore pressure data to the failure surface gave a factor of safety close to unity. This agreement between field behavior and the stability analysis sug- gests that 6' based on consolidated-undrained tests is most suitable for use on field problems which involve organic soils. CHAPTER II LITERATURE REVIEW Information on the mechanical behavior of fibrous organic soils is limited. Often in the past it was easier and more economical to avoid these deposits or to replace them with select fill material. Recently due to the need for better utilization of land, much research has been conducted on the mechanical behavior of high ash papermill sludges. These materials are very similar to fibrous organic soils, hence much information is drawn from published research on these materials. This literature review attempts to summarize the available infor- mation appropriate for this project on the mechanical behavior of organic soils. It is presented under the following headings: organic soils, physical properties of organic soils, surface area determination of small particles, compreSsibility of organic soils,and shear strength of organic soils. 2.1 Organic Soils Organic soils are reviewed under the headings of natural deposits and landfills. 2.1.1 Natural Deposits Organic soils consist of solids which are predominantly derived from plant matter in various stages of decomposition. The common designation is bog, muskeg, peat and muck. Muck has a higher degree of decomposition compared to peat which has plant remains relatively 4 well preserved (Winterkorn and Fang, 1975). The occurrence.of organic soils depends upon the topographical and hydrological conditions of the terrain. Standing water and areas with rising water table are favorable conditions. Environment and plant ecologic factors have a significant influence on these soils which are best considered as organic terrain (Muskeg) and are classified according to the genetic principles as has been done by the Muskeg Subcommittee of the National Research Council of Canada (MacFarlane, 1969). Identification is based on the organic content (Winterkorn and Fang, 1975), muck consists of thoroughly decomposed organic material with considerable amounts of mineral soil and some fiberous remains. When considerable fiberous material is present it may be classified as peat. The plant remains can sometimes be easily recognized. Color ranges from brown to black. Muck occurs in lowlands and swamps and has high shrinkage upon drying (Winterkorn and Fang, 1975). The composition of peats is predominantly fiberous with a sponge- like nature which is related to their ability to have high natural water contents. The water content may vary from 50 percent to as high as 2000 percent. Void ratios are also high having an approximate range of 5 to 15. In certain cases a void ratio as high as 25 has been en- countered. It has high drying shrinkage, up to 50 percent, low bearing capacity and high compressibility. The specific gravity of peat ranges from 1.1 to 2 and values above 2 indicate the presence of mineral matter which may be ascertained by the determination of ash content. The per- rneability of natural peat deposits varies widely and depends upon the effective size of the voids. It also depends upon the water that is held physicochemically on the external and the internal surfaces. Permeability is usually greater in the horizontal direction than in the vertical (Winterkorn and Fang, 1975). Low specific gravity of organic matter and water leads to low unit weights of peat. Tensile and shear strength of peat is provided in their natural state by the felt-like interwoven fibrous material. Thfs is the reason why the tensile and shear strength do not always increase with decreasing water content. Peat will not display its original high water content after it has been once dried upon rewetting. Natural peat shows a decrease in strength once its natural structure is disturbed. The sensitivity of peat varies from 1.5 to 10 (Winterkorn and Fang, 1975). 2.1.2 Landfills The paper industry removes a large percentage of the suspended and dissolved matter from their effluent streams. In the United States an estimated 2,500,000 dry tons (2.300 x 106kg) of waste solids, having a volume close to 200,000,000 cubic yards (150 x 106m3) are removed annually (Gillespie, Mazzola, and Gillman, 1970). Today, disposal of these large volumes of pulp and papermill sludges presents a major problem for the paper industry. More than 1,100 acres (4,450,000m2) of land are used as depositories for these man-made waste materials. Disposal to date has been accomplished by some type of landfill opera— tion, usually lacking rationale and being only a temporary measure. The procedure has been to purchase conveniently located waste land such as an abandoned gravel pit, fill this area to the elevation of the surrounding area, then cover the sludge with a layer of soil and move the operation to a different area. Only in a limited number of cases has any attempt been made to place the sludge in an embankment above ground and then it has been mixed with sand and gravel. Bacon (1967) has suggested the possibility of using sludge as an economical method for land reclamation, especially in marginal lands, coal mining areas, etc. A survey conducted by Gillespie (1969) indicated that land- fills are in wide use for the disposal of papermill waste solids throughout the United States. However, landfills are not necessarily an inexpensive or trouble-free means of disposal. Many land disposal sites have experienced difficulties with the waste. Part of these difficulties arise due to the lack of understanding of both the engine- ering properties and field behavior of these materials. In order to use this material safely in the form of embankments or foundation material for structures the behavior of the material from an engineering point of view must be understood. Since the composition of these sludges is very similar to that of peat or muskeg it is assumed that the behavior would approximate that of highly organic soils. 2.2 Physical Properties of Orggnic Soils Physical properties of organic soils-characterize, to some extent, the quality of the material relative to engineering purposes. 'The pro- perties discussed below include the description and structure, density, and swelling properties. 2.2.1 Description and Structure The term cellulose represents a group of high molecular weight substances. The most reliable molecular weight values have been obtained by the ultracentrifugal method (West and Todd, 1955). This method gives the average molecular weight of native cellulose as about 570,000 and for pure cellulose which is partly broken down as 150,000 to 500,000. The structure of the repeating units of the cellulose chain is expressed as follows. ._.__.__/ 1: \.._.__ 3 Figure 2.1. Repeating celluboise unit of cellulose (White, Handler and Smith, 1964). Cellulose fibers are composed of amorphous and crystalline regions. X-ray analysis of cellulose fibers reveal that they consist of bundles of cellulose chains running parallel. These chains are held together horizontally by hydrogen bonds between the alcoholic hydroxyl groups. The cell wall, for example, may be thought of as a finely interwoven network of cellulose strands of varying complexity and size. The smallest structural units of the cell wall are called the elementary fibrils or micelles. These micelles consist of approximately 100 individual chains of cellulose and have an estimated cross-sectional area of BOOOAZ. The next larger strand called the microfibril is thought to be composed of approximately 20 micelles and the cross- sectional area is about 62500A2. The individual cellulose molecular chains cannot be observed with the scanning electron microscope but the micelles and the microfibrils are clearly discernable when viewed under the electron microscope. A combination of approximately 250 J “ _‘-. .1 .__'-~- 0. 100 000 O———’ O Cellulose 0 molecular 3000 A2 . 0.1692 chain Micelle Microfibril F1br11 Figure 2.2 Diagrammatic representation of the association of molec- ular cellulose strands showing the approximate cross- sectional area (after Denlin, 1966). 10 microfibrils will make a microscopic fibril having a cross-sectional area.of about 0.1602. A cotton fiber which is easily visible to the unaided eye may contain as many as 1,500 fibrils. A simple calculation will show that there are about 7.5 x 108 individual molecular cellulose chains in one macroscopic cotton fiber which is 90 percent cellulose, for example (Figure 2.2). 100 x 20 x 250 x 1500 = 7.5 x108 chains. 2.2.2 Density Cellulose fibers are considered a porous body with large inner surfaces. The body of the fiber is considered porous due to exis— tence of minute internal voids. In order to determine the density a buoyancy medium which may be a liquid or a gas is required. The true volume of a porous body is understood to be the external volume of the body minus the volume of the internal voids. The true density therefore depends upon the true volume. The results of density deter- mination obviously depend upon the penetrating capability of the buoyancy medium into all voids in the porous body. If the pores are not completely filled the density values determined will be too low whereas higher values of density can be obtained for the same porous material if the buoyancy medium used is such that it could get com- pressed within the pores of the body. This has been found (Hermans, 1949) to be the case when gases such as hydrogen and air are used in porous carbon. According to Hermans (1949) Williams reported that with ceramics, and Cude et a1 (l920)with charcoal, the density found depends upon the displacement medium used. Varying values of carbon density were obtained using different organic liquids and 11 these values were smaller than the values obtained utilizing X-rays. When gases, such as air, were used the values of density obtained were higher since air was absorbed by the carbon and compressed (Hermans, 1949). According to Hermans (1949), Howard and Hullet utilized helium as the buoyancy medium for the density determination of carbon and reported values of density close to the true values because helium ltd cellu- was not absorbed by the carbon. These findings were adopted lose fibers by Heertjes (1938). Table 2.1 shows the values of cellu- lose densities obtained by using helium, toluene, and water as a buoy- ancy medium. Note that density values obtained are lower in organic liquids compared to those obtaining using water which are higher than values determined using helium. According to Hermans (1949), Davidson also discovered that equal values are obtained when benzene, tuluene, chloroform and nitrobenzene are used as the displacement medium. Organic liquids produced density values which are too low because these liquids failed.to penetrate the small voids in the cellulose fiber. Water has the capability of penetrating the pores of the cellulose fiber therefore producing a higher value of the density. Small helium atoms, on the other hand, can penetrate the pores without any resis- tence and fill the pores entirely. Density and porosity are typically macroscopic concepts. This property is of practical value only if applied to bodies or voids with physical dimensions which are very large compared to molecular dimensions. Neither volume nor density can be defined in the usual sense without taking into account the relative dimensions and shape of the molecules of the substance and the buoyancy medium. Consider a pile of spheres, the bulk density of which is required to be determined by 12 TABLE 2.1. DENSITIES 0F CELLULOSE FIBERS IN VARIOUS BUOYANCY AGENTS (AFTER HERMANS, 1949) Author and object Buoyancy medium used Helium Toluene Water G. F. Davidson Native cotton American Upland 1.567 1.550 1.6095 Sea Island 1.558 1.548 1.6038 Sakel 1.563 1.550 1.6061 Mercerized cotton American Upland 1.550 1.536 1.6066 Sea Island 1.546 1.531 1.6017 Sakel 1.550 1.536 1.6041 Viscose rayon 1.548 1.5341 1.6081 Cuprammonium rayon 1.531 1.522 1.6005 Nitrocellulose rayon 1.543 1.529 1.6149 W. Biltz Heptane Native cotton --- 1.540 --- Viscose rayon --- 1.516 --— H. L. Bredée Benzene Viscose rayon, little orientated --- 1.513 1.604 better orientated --- 1.519 1.608 greatly stretched --- 1.522 --- Lilienfeld rayon --- 1.534 1.594 1 This value of Davidson's is undeniably far too high. In a later investigations lower figures were found for rayon. using a medium which consists of smaller spheres. The result woul 11 d depend upon the relative dimensions of the spheres and will follow the rules of spherical packing. If the spheres of the medium are small enough to penetrate the voids between the larger spheres the density values obtained will be suddenly increased compared to the density values obtained by utilizing a medium consisting of larger spheres unable to penetrate the voids. The same principle applies to porous bodies and the density values obtained would depend as to how acces- sible the pores are to the molecules of the displacement medium. The 13 ease with which a buoyancy medium can penetrate a porous body would also depend to a certain extent upon the molecular coarseness of the pore walls (Hermans, 1949). Contraction resulting from mixing two types of spheres can also be explained on the basis of geometrical reasons if the molecules of one liquid like water penetrate and settle themselves in the voids between the molecules of some other substance. The macroscopic density of a substance is greater in the crystallized state when compared to the same substance in its amor- phous state with few exceptions of which water is one. The reason is the less orderly arrangement of molecules in the amorphous state resulting in larger empty spaces between the molecules. Since cellu- lose fibers consist of a mixture of crystalline and amorphous regions (Eirich, 1958) obviously the density would depend upon the quantitative distribution of the crystalline and amorphous parts. The high density values of cellulose in water are considered normal results of the homo- geneous mixing of water and cellulose in the amorphous portion (Hermans, 1949). The bulk density can be determined using a liquid which does not penetrate into the fiber substance but envelops it. The density obtained in this fashion would be the macroscopic or bulk density. 2.2.3 Swelling Properties When water is accessible to fibers, absorption starts and fibers commence to swell. The first stage of swelling consists of the forma- tion of hydrates. More and more water is attracted resulting in further covering of the chains in the amorphous regions. Swelling accompanied by the formation of thick layers of water continues. This last stage is termed "capillary condensation" with capillaries forming after 14 swelling takes place (Hermans, 1949). According to Hermans (1949), the end value of swelling should not be associated directly with the percentage of the amorphous substance present. The final swelling value probably depends upon the structure of the micellar system or in other words the extent to which the geometrical structure can ex- pand while absorbing water without giving rise to resistance caused by excessive strain. Swelling characteristics can be substantially affected by introducing a slight change in the gel structure. Swell- ing in rubber can be reduced by vulcanization and the extent of this reduction depends upon the number of cross linkages (Hermans, 1949) introduced in the structure. It is obvious that the structure and the swelling characteristics, especially of artificial fibers, will depend upon the conditions under which these fibers were manufactured. Depending upon the history of drying, causing the introduction of cross linkages, the swelling characteristics of fresh fibers and fibers sub- jected to drying should be expected to be different. According to Hermans (1949) an interesting observation made by Risch, after treating rayon filaments for three hours under pressure with water vapor at 103° to 115°, was that water absorption dropped to approximately one-half of the initial value while swelling. In its dry state, the cellulose fiber is brittle and nonflexible. Cohesive forces in the micellar system are so powerful at all points that it becomes rigid. Thus water is a typical softener to cellulose (Hermans, 1949). Attention should be given to the dual function of the hydroxyl groups in cellulose. The firm cohesion between molecules in a cellu- lose gel and the insolubility of cellulose in water is a result of the powerful forces between OH groups which are also responsible for 15 the hydrophyllic' nature of cellulose. This duality can be explained as follows. The first function is due to those hydroxyl groups which 7 are reciprocally bound by hydrogen bonds and the second function is because of the presence of free OH present in other locations (Hermans, 1949). Hydrogen bonds form where the chains are very close to each other and where the maximum degree of order exists. Whenever the hydroxyl groups of the neighboring chains are not in close proximity they remain free due to their inability to act at large distances. One of the more important facts (Hermans, 1949) relative to swelling of fibers is the change in dimensions revealing the anisotropy of fibers. Almost all the dimensional changes take place widthwise with relatively negligible change lengthwise. This behavior is due to molecular chains which are oriented in the direction of the fiber axis. Water can only penetrate the fiber laterally between the chains or between the crystalline regions. According to Hermans (1949), Urquhart reports that volume change due to swelling of cotton in water is approximately 45 percent. Lengthwise swelling is less than 1 percent. Artificial fibers from cellulose swell by 70 to 100 percent with only 2 to 5 percent longitudinal swelling. .7 7» 2.3. Surface Area Determination of Small Particles Surface area of small particles provides the geotechnical engineer with information that helps explain the mechanical behavior of the material. Some knowledge of the methods used to measure surface area provides a background for discussion in later sections. A review of absorption, the solid-gas interface, the Langmuir and B.E.T. (Brunauer, Emmett, and Teller, 1938) equations are presented since sorption of l6 nitrogen and water vapor have been used to determine surface area of the pulp fibers. 2.3.1 Adsorption Part of the gas or vapor is taken up by an evacuated solid when they are allowed to come in contact with each other. If this process is allowed to occur at constant volume the pressure will drop or if the pressure is kept constant a reduction in volume will result. The gas molecules lost to the solid from the gas phase either penetrate inside the solid or settle on the surface of the solid. The former phenomenon is termed absorption and the latter adsorption. Absorption and adsorption often occur simultaneously. The total uptake of the gas by the solid is called sorption. In order to study adsorption the experiments must be conducted at temperatures, pres- sures and concentrations at which either the absorption of the gas is negligible or the two processes can be isolated with an acceptable degree of accuracy. Adsorbent is defined as the solid that takes up the gas. The gas or vapor attached to the surface of the solid is designated as the adsorbate. It is usually difficult to distinguish whether the gas or vapor molecules are inside or on the surface of the solid. Most solids are highly porous bodies having large internal sur- face areas. The external surface, studied under the best microscope, is only a small fraction of the large total surface. Gas molecules are considered to be on the outside even if they are adsorbed on the internal surface of solid as long as they do not penetrate into the field of force that exists between atoms, ions or molecules inside the solid. 17 If the gas penetrates the inside of the adsorbent there are two possibilities that might result: the gas dissolves in the solid forming a solid solution or a compound may result due to the reaction between the gas and the solid. If the gas molecules settle on the surface of the solid, again, there are two events that could happen: a weak interaction may take place between solid and gas similar to con- densation or a strong interaction like chemical reaction may result. The first weak interaction is defined as physical adsorption and the strong interaction is called chemical adsorption or chemisorption (Brunauer, 1943). 2.3.2 The Solid-Gas Interface The surface of the adsorbent is the place where gas and solid come in contact with each other. The molecules and atoms in the solid are firmly held in place due to the existence of several active forces like, electrostatic, Van der Waals, etc. In solids several of these forces are in action simultaneously with one or the other predominating. An atom located inside the solid is subjected to an equal force from every direction regardless of the nature of the operative forces. An atom situated in the plane of the surface is under the action of an inward pull and therefore under unbalanced forces resulting in a ten- dency of volume shrinkage and a decrease of surface. A solid has sur- face tension just like a liquid. The surface tensions of solids are much greater than those of liquids. The surface tension of benzene at 20°C is 28.8 dyne/cm while that of Barium Sulphate is 310 dyne/cm (Brunauer, 1943). The free surface energy is defined as the product of the surface 18 tension and the surface area. Any process which carries a tendency to decrease the free surface energy proceeds spontaneously. The molecule or atom of the gas adsorbed by the solid relieves some of the unbal- anced surface tension force. Therefore, all adsorption phenomenon that may be physical or chemical are spontaneous and cause a decrease of the free energy of the system (Brunauer, 1943). The adsorbed molecules are either held rigidly to the surface or they can shift over the surface freely in two dimensions. Before adsorption gas molecules were free to move in all three directions, therefore the adsorption process is also associated with a decrease in entropy. All adsorption processes are exothermic. The decrease in the heat content of the system is called the heat of adsorption. The heat of the physical adsorption of nitrogen on an iron catalyst is about 2000-3000 calories per mole. The heat of chemisorption of nitro- gen on the same surface is 35,000 calories per mole (Brunauer, 1943). In the former case nitrogen is adsorbed in the molecular form while in the latter case it dissocates into atoms. Only one chemisorbed layer results since the surface iron atoms andxnitrogen atoms mutually sat- urate each others free valence forces. In phySical adsorption adsorbed nitrogen molecules on the iron surface can absorb a second layer of nitrogen molecules and these in turn can attract a third layer and so on. Single layer adsorption on the surface is called unimolecular or mono- molecular adsorption. More than one layer is designated as multi- molecular. 19 2.3.3 The Langmuir Equation There was no satisfactory theoretical treatment available that could be applied to surface adsorption until the pyear 1914. In the year 1915, according to Brunauer (1943), Polanyi and Langmuir presented their independent theories. The approach taken by each individual was different. Langmuir believed that the adsorption phenomenon was a chemical process and the adsorbed layer was a single layer which is termed a monomolecular layer or unimolecular layer. Polanyi on the other hand claimed that the adsorption was a physical process and the adsorbed molecules formed several layers on the surface of adsorption. Both of these approaches are correct within their limitations. Polanyi's theory applies to Van der Waals adsorption whereas Langmuir‘s theory can be applied to both physical and chemical adsorption. There are at present several isotherm equations (Brunauer, 1943) that have been developed which fit satisfactorily the experimental data but in most of their derivations the starting point is the Langmuir equation. For this reason the Langmuir equation is considered to be the most important equation in the field of adsorption and therefore the ori- ginal kinetic derivation of Langmuir will be reviewed. The kinetic derivation (Brunauer, 1943) assumes that the molecules of gas and vapor are in constant agitation. When these molecules are allowed to come in contact with a solid surface, two things can happen. The collisions taking place between the molecules and the solid sur- face may be an elastic collision, i.e., rebounding the molecules into the gas phase or inelastic collision where the molecule rests on the solid surface for a certain length of time. No exchange of energy 20 takes place between the surface and the gas molecules during elastic collision whereas energy exchange does take place during inelastic collision since the molecule stays in contact with the surface for a certain period of time before it leaves the surface and returns to the gas phase. Langmuir (1918) believed that this time lag was responsible for the phenomenon of adsorption. Ordinarily, the collision is in- elastic, however, very infrequently elastic collisions may occur. At high temperatures the time of stay of the molecules on the surface is very short and therefore thermal equilibrium is not reached. On the other hand in chemisorption which involves strong binding between the molecules and the surface the time lag may be long. Langmuir let the rate at which the molecules strike the surface be denoted by u and let the rate of departure of the molecules from the surface be denoted by v. The net rate of adsorption is therefore given by (Brunauer, 1943) %%-= on - v (2.1), where 5 denotes the number of gas molecules adsorbed per unit area, say, per square centimeter surface. The ratio of the number of mole- cules that condense on the surface to the total number of molecules that strike the surface is termed the condensation coefficient and in the above equation it is denoted by a. As mentioned earlier, the elastic collisions are infrequent, therefore the numerical value of a is always close to unity. When equilibrium is established the number of molecules adsorbed equals the number of molecules that are departed, therefore, 21 d a%-= 0, and (2.2) up = v (2.3) which is the isotherm equation in its most general form. From the kinetic theory of gases the value of u for a unit surface is obtained from the following relationship (Brunauer, 1943) u = ———P————— (2.4) (ankT) M\"‘ where m denotes the mass of the gas and k denotes the Boltzmann's constant. The value of v is a function of the binding strength be- tween the solid surface and the molecules of the adsorbate. If q is the quantity of heat that is released during the adsorption of a single molecule then the molecules that would desorb will be the ones which require heat equal or greater than q. The rate of evaporation will then be given by (Brunauer, 1943) v = k,e‘°/kT (2.5) The average probability of evaporation per second for a single molecule is obtained if v is divided by s, i.e., the number of molecules that leave a unit area of surface per second by the total number of mole- cules adsorbed on a unit area of surface. The reciprocal of this quantity (v/s) will yield the average time that a molecule stays on the surface,therefore T = s/v (2.6) The prevalent forces during the adsorption process are effective only through short distances. The effectiveness of the forces dies down with distance. Valence forces decrease exponentially with increasing 22 distance between the surface atoms and the molecules of the adsorbed molecules and the Van der waals forces decrease with the seventh power of the distance (Brunauer, 1943). Because of this very rapid decay of force with distance it is very unlikely that a surface covered with a single layer of adsorbed molecules will still have sufficient residual effective force left to provoke the settlement of a second layer of molecules on top of the first layer. But a second layer may form if the force of interaction between the molecules adsorbed on the surface and the molecules in the gas phase are sufficiently strong. The equation v = koe-q/kT indicates that a small change in the heat quantity q can cause a large change in the rate of evaporation. Let q1 be the heat of adsorption in the first layer and q2 be the heat of adsorption in the second layer. Langmuir (1932) has discussed the two cases, q1 < q2 and q1 > q2' When q2 > q], i.e., when the forces between the molecules of the adsorbate are greater than the forces between the molecules of the gas and the molecules of the surface,the molecules of the adsorbate will adsorb on the surface in clusters. On top of these single layer clusters, a second, third or higher layers of molecules may form before the monomolecular layer on the surface is complete. For example, when molecules of iodine, cadmium or mercury condense on a glass surface at not too low temperatures, crystals of the condensed substance are formed, clearly demonstrating that the force between two iodine molecules is larger than the force between an iodine mole- cule and molecules of the glass surface (Brunauer, 1943). Langmuir (1932) believed that when q2 > q], discontinuous condensed films are obtained, rather than true Van der Waals adsorption. If this situation 23 exists then the isotherm obtained are convex towards the horizontal axis (pressure axis). In the case of the more usual types of isotherms the part of the curve at low pressure is concave towards the horizontal pressure axis. In this case q1 > qz. As the pressure increases the surface is progressively covered with a monomolecular layer of adsor- bate. In chemisorption q1 is very large compared to q2 and therefore the formation of second adsorbed layer does not result. In Van der waal's adsorption q1 is slightly greater than q2 and therefore the formation of a second layer commenses before the completion of the first layer occurs. The quantities a, u and v are functions of p, T and 5. Instead of using the surface concentration, the fraction of the surface covered with molecules can be used. Let 5 denote the number of molecules per square centimeter, then a = 51/3 (2.7) where 51 denotes the number of molecules which cover the fractional area 6. Langmuir has introduced two assumptions in his derivation. The first assumption states that the probability of evaporation of the adsorbed molecule is the same regardless of whether the space on the surface adjacent to adsorbed molecule is occupied by another molecule or not. In other words, the mutual force exerted by adjacent molecules resting on the surface is neglected. This assumption is expressed mathematically (Brunauer, 1943) as, v = v 0 (2.8) where 0] denotes the rate of evaporation from a completely saturated surface. The above equation also assumes that uniform heat of 24 adsorption is taking place over the entire surface. Langmuir's second assumption states that molecules from the gas phase that strike the already adsorbed molecules on the surface rebound elastically and returns to a gas phase where those molecules from the gas phase that strike the bare surface condense on the surface. This assumption is expressed mathematically (Brunauer, 1943) as, up = aa(1-6)u (2.9) where (1-0) is portion of the surface unoccupied by the adsorbate molecules and a, is the ratio of the number of molecules that condense on the surface to the number of molecules that strike the surface. Because elastic collisions are infrequent on the bare surface the numerical value of do is close to unity. Substituting 0 = 010 and up = a°(1-0)u in up = 0 gives 010 = ao(1-0)u (2.10) v1e + °°°“ = °°“ (2.11) do (1011 U]— 11 e _ ______V1 + do“ - _—d. (2.12) . 1 +____ IJ "1 This is the Langmuir isotherm equation (Brunauer, 1943). This equation is usually written in the form 6 =-—Jml—— (2.13) where b denotes the absorption coefficient and is calculated from the relationship (Brunauer. 1943), 25 doeq/kT b = —-——,— (2.14) h(&mKD?. If v denotes the volume adsorbed at pressure p and vm denotes the total volume adsorbed when the surface is covered with a complete monomole- cular layer, then 6 = v/vm (2.15) substituting a = 1£€FTNE for e (2.16) . vmbp glVES V = W The two assumptions in the Langmuir derivation of the isotherm equation restricts the application of this equation yet this equation has found its use in a large number of instances (Brunauer, 1943). 2.3.4 The B.E.T. Equation When molecules strike a layer of molecules that are already adsorbed on the surface and if the force of attraction between the striking molecules and the adsorbed molecules is sufficiently great, then their time of adsorption may not be small enough to be neglected. If this happens then conditions for multimolecular adsorption are met. Attempts have been made for the derivation of an isotherm equation for multimolecular adsorption. The most successful attempt was made by the combined effort of Brunauer, Emmet and Teller (1938). They also assumed in their derivation that the molecules of one layer do not mutually influence each other while the building up of the layer pro- gresses. They have also made the assumption that the adsorption energy 26 of the first layer is constant and the heat of adsorption in each of the following layers is also constant. They let 61 represent the fraction of the surface area that is covered by a single layer of molecules and 82 represent the fraction covered by two layers of molecules such that one layer is resting on top of the other. Similarly, 63 represents the fraction of surface area covered by a layer which is three molecules thick, hence 6, will represent part of the surface area covered by a layer the thickness of which is equal to 1 molecules. If the unit area is taken to be one square centimeter then the total number of molecules adsorbed on one square centimeter area is (deBoer, 1953), n = noe1 + 2n°02 + 3n°03 + ,. . .,in°0i + ,. . . (2.17) where n, is the number of molecules that would cover a unit area of one square centimeter with a complete unimolecular layer. n = no 2 ie. (2.18) When equilibrium is reached the fractions 61, 02,. . .,0i remain constant. This also means that the bare part of the area is also constant. If we denote the bare fraction of the area by a, then 6° :1 - e] - 62,. o ogei (2.196) or = 00 = 1 - Z 0. (2.19b) Since the fraction 60 remains constant at equilibrium, this means that the number of molecules adsorbed on the bare area (reduces 9,) should be equal to the number of molecules that evaporate (increases 27 e.) from a layer one molecule thick. If the number of molecules adsorbed is n60 and the number of molecules evaporating from fraction 61 is Once], then 06a = vnae1 (2.20) where n is the number of molecules striking one square centimeter area per second and v is the rate of evaporation. Similarly the fraction 61 is maintained by molecules adsorbed on the bare surface (n00) and by moleclues evaporating from the top layer of the fraction 62(v1n092). Both of these phenomenon will increase the fraction 61 and in order to maintain a] constant there must be molecules evaporating from 61 and other molecules being adsorbed on top of 61 (deBoer, 1953). For example, Adsorption on bare surface = 06,. Evaporation from 92 = 01n062 Increase in e] = nee + v1n602 Evaporation from 61 = unae1 Adsorption on 61 = ne1 Decrease in 61 = ne1 + Once1 Since 61 should remain constant, n0o + 01n062 = n61 + Once]. Since n6° = Once], then n61 = VIUOOZ. Continuing the argument in a similar fashion, n91_1 = vi-l no 9,. Since Vi denotes the rate of evaporation from a unit surface the reciprocal of this rate of evaporation will give the time of adsorption, 1 therefore, ti =:gf . 1 28 Substitution gives the following set of equations (deBoer, 1953) n001 t n 00 noez = t1 n 61 noei = ti'] n 61—] (2.21) where t denotes the time of adsorption of those molecules which are directly resting on the surface, t1 denotes the time of adsorption of the molecules adsorbed on the first layer and so on. Since the mutual attracting forces between the molecules of the same kind is approxi- mately the same the time of adsorption of a molecule bound on top of another molecule of the same type will be the same regardless of the number of layers (deBoer, 1953). Therefore, (2.22) From the above equations, : = 1 : n°02 t1n01 or 02 Do 0.l x01 where '”7 ’7“ t1n x = no S1m11ar1y, 0,03 = tzne2 and n063 = t1n62 s1nce t1 = t2 t n _ l _ _ 2 01‘ 63"“:- 92-x92—x6] e. = x e (2.23) theo ttlneo t0o Now, = o: = -——-= --—-—:-= ——- n061 the or 01 no not] x t]. 1to 1:” Therefore, e.,= 5———£—, and n = n0 2 i6. 1 t ._ 1 1 1-1 Substituting for 6i . i=oo . n _ o 3%3- 2 1x1 1 i=1 1:00 1:00 . and ea = 1 - Z 6i = 1 - 3%3- Z x1 i=1 1 i=1 Therefore 6, = t 1._ . 1 + ——-]-m x1 i=1 t . . . . te 1:” i Let E—-= w, and subst1tut1ng for a, 1n the equat1on n = no t ° 2 1x 1 1 i=1 i=0° i new 2 IX gives 0 = }:l (2.24) 1+0) 2 X1 i=1 The summation in the numerator can be written as i=m i x 2 ix = 2 (2.25) i=1 (l-x) and the summation in the denominator can be written as 1:” i x Z x =-——— (2.26) 30 Substituting into equation 2.24 gives x nawx T1000 —— n = (I'X)2 = (I'X)2 1 + g§__ 1 - x + wx l-x (l-x) or n = ”°w (2.27) (l - x)(1 - x + m) where x is a dimensionless quantity and is equal to ntl/no. As n is pro- portional to the pressure, p, then n is given by the relationship (deBoer, 1953), n = --flE—--= Bap (2°28) «(z—71ml where: N = Avogadro's number = 6.023 x 1023, R = Molar Gas constant, T = Absolute temperature and M = Molecular weight. Let, Sept] x- no where DEE- has the dimensions of preSsure and will be denoted by q, hence x = p/q. Now if the magnitude of pressure, p, is increased until p equals q, then the value of x becomes equal to unity. This would mean that n the value of n corresponding to the pressure q, is such that q, llqt] = no Physically, this equation means that, if the adsorption takes place on a free surface, then the second, third, etc, layers are filled to capacity, i.e., no molecules are adsorbed on one square centimeter 31 surface area (deBoer, 1953). Substituting x = 1 in to equation 2.27, the value of n becomes infinity. Substituting x = p/q in to equation 2.27 gives now P- M q = C] = 110(4) (1 - §9(] _ g +(nga (Qfiflq(1 + 2%.- g) (Q'P)[1 + «D'IIP/QJ where (g, q and no are constants. Instead of expressing this equation in terms of number of molecules it can also be expressed in terms of the volume of gas which has been adsorbed. Let the volume ofll molecules be equal to v and let the volume of TC molecules be vm (deBoer, 1953). Then substituting for n and TL in the above equation gives pr = m (2.29) (q-p)[l + (4-1) 43—1 V If the three constants w, q and vm are determined from experimental results, then the value of vm gives a direct measure for the surface area of the adsorbent. Brunauer, Emmet and Teller (1938) further simplified this equation by taking q as the pressure at which the saturation value of the adsorbate is obtained at the temperature of the experiment. Replacing q by pa gives v'= mm (2.30) (pa-pm + (o-n 53—1 Now if v is plotted as a function of P/Po. the value of'v will approach infinity as P/Po approaches unity. Note that at the point where P/Po = 1 the curve approaches a vertical line asymptotically. 32 Equation 2330 can be nearranged (deBoer, 1953) as TL)”; w-L V po'p wv + me po (2.31) m I By plotting VIE—:PT' against p/pa the intercept on the vertical axis equals 5%—- and the slope of the straight line portion equals 351' m m from which the two unknown constants Vm and w and therefore the surface area can be calculated. '2.4 Compressibility of Organic Soils Organic soils have a reputation for being very compressible. This volume change occurs due to decrease in volume of gas bubbles. drainage of water from the sample, and compression of the solid ma- terial. Consolidation behavior of the soil and compressibility of the solids are reviewed in this section. 2.4.1 Consolidation Behavior Organic soils consist of mineral solids and organic material in various states of decomposition. Some peat soils are fibrous, others show little or no fibrous texture. Pulp and papermill sludges are similar to organic soils. These organic soils may be considered to be a skeleton of solid particles or fibers enclosing macrovoids and micro- voids which may be filled with air, liquid or a combination of the two. If a sample is subjected to an external load,compression of the sample will take place due to l) compression of the solid matter, 2) compres- sion of water and gas, and 3) escape of water from the sample. Under the usual loads encountered in engineering problems,compression of solid 33 and water is negligible. Compression of air trapped in macrovoids and the change in volume due to escape of water can be finite. The problem of determining the change in volume can be complex since . compression of air may take place without allowing water to escape. ‘Compressibility and the rate of consolidation for organic soils will be influenced by soil composition, water content and permeability.;) Composition of the organic soil will vary with time depending upon I the extent of decomposition that has taken place. For example, the solid content of papermill sludge can vary from 5 to 65 percent depend- ing upon the method of dewatering. The result is that the physical properties of sludge can show a wide variation. Various micro-organisms are responsible for decomposition of the organic matter. Waksman (1960) showed that cellulose decomposition is dependent upon a faVorable carbon to nitrogen ratio. Imshenetsky (1968) indicated that cellulose decomposition ceases when the available nitrogen content of a soil is below 1.2 percent. Other factors influencing decomposition include temperature, aeration moisture content, pH value and the relative proportion of lignin. Compressibility of soil is a function of the extent to which particles can shift with respect to each other to attain more stable positions. The rigidity of the soil skeleton depends upon the rigidity of the solids, shape of solids and the binding forces between solids. A coarse fibrous structure may exhibit a different compressibility from a fine-fibrous structure. The compressibility may also vary with the amount of amorphous material and crystalline material present in the cellulose. Compressibility is a function of the water content 34 of the soil. Water found in cellulose exists in three different phases (Gehm, 1959) 1) free water, 2) interstitial water, and 3) water of imbibition. Free water will drain readily. Interstitial water—TS,” held by adsorption on the fiber surface and is difficult to remove. Water of imbibition is a part of the structure of cellulose fiber and it Cannot be removed by mechanical means. Water content in organic soils depends to a large extent upon the proportion of organic matter in the sample.' For example, water content in peat soils may varyfrom 50 percent to 1000 percent. The rate of compression is dependent on the permeability of soil. The presence of cellulose fibers increases the permeability and there- fore the rate of compression. The physical structure and the arrange- ment of constituent particles in organic soils greatly effect the size and continuity of pores and/or capillaries. These differences plus incomplete saturation result in a wide range of permeabilities in organic soils. The effects of undissolved gas in peat Show up parti- cularly in consolidation tests (MacFarlane, 1969). In laboratory consolidation tests, a large initial compression and an indistinct completion of primary consolidation in time-compression curves reflect the presence of gas. The basic assumptions made in applying conventional consolidation theory to inorganic soils include 1) homogeneous material 2) complete saturation, 3) negligible compressibility of the solid matter, 4) validity of Darcy's law, and 5) constant properties during each stage of consolidation. Application of consolidation theory to peat soils includes major deviations from assumptions three and five, 35 -compressibility of gas within a solid particle and change of per- meability under applied load. MacFarlane (1969) indicates that these two anomalies account for the significant differences in consolidation behavior between organic and mineral soils. A porous material subjected to an all around compression under drained conditions will experience a decrease in volume. If, for example, the pressure is increased by a small amount from p' to p’ + Ap‘ the corresponding change in volume will be from V to V + AV. Where AV denotes the decrease in volume and therefore is negative. The ' volume compressibility of a material is defined as the change in volume W per unit volume per unit pressure, therefore the compressibility of the material for the particular pressure increment is given by the relation- ship, - A-V—(l c (2.33a) av many .1 cu .. . mpawxmpu.1 3m, m F—mo —mwxewcp Any . a mono Pocacoo 3m+um use; .. .. V233: _ a \ s .e — __ n __ we . N ”Hamil “@508. m h. w» .Po> u .o 4 uuommm P 4 . Mg“; f m.» . 3 . w Agzucmz fi mmsem mesmmwca cope: r ‘ _ . a: so -3325 _ m Ema 63 pressure to be applied; and the loading ram which applies the deviator stress to the sample. This cell was connected to a burette, to the self-compensating mercury pressure control, and through a mercury U-tube "9" (Figure 3.2) to a pressure gauge and a pressure control cylinder. The pore pressure measuring device consists of a pressure gauge, a pressure control cylinder, and the mercury U-tube. This device, which connects to the bottom of the test sample through a line con- nected to mercury U-tube passing through the pedestal, permits measure- ment of pore pressures developing in the specimen during the process of testing. 3.4.2 Sample Preparation Samples prepared and tested were divided into the following four groups depending upon their composition: 1) all fiber, 2) 54 percent fiber and 46 percent kaolinite by volume, 3) 25 percent fiber and 75 percent kaolinite by volume, and 4) all kaolinite. Uniform combinations in the specified weight (or volume) pro- portions were obtained by mixing dry kaolinite with freeze dried loose cellulose fibers. Water was added until the water content was greater than the liquid limit. Samples representing groups (2), (3) and (4) were trimmed from a larger normally consolidated cylin- drical sample to give the desired 2:1 length-diameter ratio. A rotary-type of cutting tool permitted trimming of the fibrous material. For easier preparation, samples consisting of all fibers ~— 64 (group 1), were molded in a split cylinder to give a specimen with the desired dimensions. ' 3.4.3 Consolidated-Undrained Tests This test consisted of mounting the specimen, provided with side drains, on the pedestal inside the cell (Figure 3.2b). The sample was l:i’acketed in two rubber membranes and consolidated by keeping valves "a" and "b" open, with respect to a desired three dimensional pres— sure applied through the fluid in the cell by the self-compensating pressure control system. For convenience the consolidation process was continued for 24 hours then valve "b" was closed. To increase the degree of satura- tion, a specified back pressure was applied to the sample in small increments simultaneously with increasing the cell pressure. The pore pressure parameter, B, was determined by temporarily isolating system (a) in Figure 3.1 by turning off valve 01, and with the screw control increasing the cell pressure by a small increment. The increase in cell pressure increases the pore pressure upsetting the balance in the mercury U-tube "9." Using screw control "51" the mercury columns were balanced and the increment of pore pressure Au was read on the dial gauge 92. The pore pressure coefficient B was calculated using the relationship, _ AE_. B - A03 (3.3) / After the cell pressure and the pore pressure were returned to their previous values, valve Gl was opened. After the sample pore pressures ”were allowed to come to equilibrium, the deviator stress was applied, 65 through a mechanically operated ram. During application of the devia- . tor stress the mercury U-tube "g" was kept balanced by turning the screw control "51" permitting excess pore pressure to be read on the dial gauge. Pore pressures, deviator stress, and axial strain were recorded at selected intervals until sample failure was observed. 3.4.4 Consolidated Drained Test The procedure followed for the drained tests was essentially the same as for the undrained tests up to application of the deviator stress. To ensure no excess pore pressure development and to permit measurement of the volume of water leaving the sample, valves "a" and "b" were opened and valve "c" was closed (Figure 3.2). The volume of water leaving the sample and entering the burette was recorded at the respective axial strain. Time to failure (20% axial strain) for the drained tests was calculated on the basis of c v from the consolidation portion of the test and the theory provided by Bishop and Henkel (1962). For all fiber sample CD-F2, cv = 11.27 x 10.3 cmz/min for a sample height = 7.306 cm, sample radius = 1.729 cm, and t100 - 32.5 min. The estimated time to failure equals about 9.7 hours. A sample deformation rate was selected to give an axial strain of 20 percent for this time to failure. CHAPTER IV EXPERIMENTAL RESULTS The experimental results are presented under four headings: physical properties ofthe test materials, compression tests, direct shear tests, and triaxial compression tests. 4.1 Physical Properties of the Test Materials Test materials used in this study were limited to kaolinite and an organic pulp fiber, both raw materials used in the paper making process. The fiber description required for this study included the weighted average fiber length, specific gravity and surface area of the pulp fiber. For kaolinite, the study included the Atterberg limits and the particle size distribution based on the hydrometer analysis. Atterberg limits were not determined for pure fiber or the fiber- clay mixture. The interference due to the fiber length during cutting the standard groove would lead to misleading liquid limit values. The determination of a plastic limit for fibers is not possible using the standard method of rolling threads of 1/8 in. diameter at a water content at which the threads begin to crumble. 4.l.l Atterberg Limits and Particle Size for Kaolinite The liquid limit (ASTM 0423—66) and plastic limit (ASTM 0424-59) were determined using a standard liquid limit device and the method of rolling kaolinite threads down to 1/8 in diameter at a water content at which it just crumbled. 66 67 Water content, w% 30 lLlL I I4 1 ll 6 8 10 20 30 40 60 Number of blows, N Liquid limit = 47.80% Plastic limit = 27.50% Plasticity index = 20.30 Figure 4.1 Water content vs. number of blows for Kaolinite. 68 Hooo. .mu_:wFoc¥ cow m>c=o cowpznwcumwu mem :_mco N.e we:m_d as .cmumEm_n geese Hoo. Ho. 1 111.144 1 q quad... d - d1 _ . , q fidd mm C) LO mu ooH JBULJ 1U83Jad 69 Table A.1 and A.2 in the Appendix show the required data for , determination of the liquid and plastic limits, respectively. Figure 4.1 shows the number of blows plotted against water content. The liquid limit, determined from the plot corresponding to 25 blows, is equal to 47.8 percent. The plastic limit, determined from averaging the data obtained from three determinations, is 27.50 percent. The plasticity index equals 20.30 percent. The hydrometer analysis (ASTM 0422-63) was performed using the model 152H hydrometer in a kaolinite suspension with sodium hexameta- phosphate (NaP03) as the dispersing agent. Table A.3 represents the data recorded for the grain size distribution. Figure 4.2 shows the size distribution of the clay particles. All sample particles passed through a 0.074 mm opening (U.S. Standard Sieve #200). 4.1.2 Weighted Average Fiber Length The weighted average fiber length was determined by a procedure used by the pulp and paper industry and described in Section 3.1.1. The measured lengths of projected fiber shadows are tabulated below the U.S-.standard sieve sizes in Table 4.1. The summations give the total length and the total number of fibers measured on the screen. The screens used were U.S. standard sieve No. 14 (1.41 mm), No. 30 (.595 mm), No. 50 (.297 mm) and No. 100 (.149 mm). Projected shadow lengths of the fibers on the screen from different slides are shown in Figures 4.3a, 4.3b, 4.3c, and 4.3d. Simple calculations for the determination of the average weighted length are derived from these projected shadows. It can also be observed from Figure 4.3 that the lengths of the fibers are decreasing with decreasing sieve opening. 70 TABLE 4.1 FIBER LENGTH CLASSIFICATION U.S. Standard Sieve Sizes No. 14 No. 30 No. 50 No. 100 1.41 mm 0.595 mm 0.297 mm 0.149 mm Projected Lengths, in. 2.75 1.50 2.10 2.55 l 1.40 1.60 1 .23 .50 .40 3 1.50 2 2.50 1.60 2.50 1.60 2 50 .50 .70 .35 2 1.40 1 2.30 2.40 2.30 2 1 20 .50 1 13 1.75 2.90 2.20 3.10 2.40 1.30 1.40 1.40 1.50 65 .70 4.75 1.40 2 4 2.10 1.40 1.50 1.50 1 1 .90 1.60 1.50 3.50 3.60 2.70 2.50 1.60 2 50 .50 1 2.50 2.60 0.75 2.60 2.90 1.60 1.50 2 50 1.30 1 13 .35 2.50 3.20 1 1.40 3.60 2.30 2.10 l 60 1.75 65 .40 3.80 4.10 2.25 3.50 1.60 1.50 2 1 50 .85 65 .50 2.80 1.60 2.25 4.50 2.60 1.80 1.40 1 50 .95 50 .70 4.00 1.50 2.25 2.25 2.40 2.40 1.60 1 50 .50 2 1 .30 3.00 1.20 3 1.90 1.60 1.50 2.10 2 .35 65 2.50 1.60 2 2.50 2.00 1.80 1.30 l 60 .90 l 3.00 1.80 4.4 1.45 3.20 1.30 1.50 1 80 2.12 75 .50 2.00 1.50 2.60 2.20 3.20 1.50 1.40 1 20 .90 l .70 1.90 2.50 1.80 2.80 5.70 2 1.70 2 4O .50 2 .40 2.80 1.00 4 2.80 1.80 1.4 1.20 2 75 1 .70 .55 4.20 2.20 2.10 1.50 2.30 1.50 2 30 2.4 .90 3 3.50 3 1.90 2.40 1.60 1 50 l .70 .75 1.60 1.80 1.50 2.20 1.70 1.50, 1 50 .35 .70 .50 2.80 l 3 4 2 2.50 3.50 1.30 1.80 .35 3.50 1.80 1.5 l 1.50 2.30 3.00 50 l 2.50 2 3.1 1.60 2.50 1.45 1 1 2.40 3.3 2.4 1.50 2.30 2.50 1.45 1.50 3.10 1.6 2.40 1.30 1.50 70 1 Total Length, in. 170.20 126.35 107.60 70.11 Number of Fibers 73 54 60 71 Scaled Average Length,* in. 2.3315 2.3398 1.7933 .9875 Actual Length,+ mm. 2.6645 2.6740 2.0495 1.1285 71 TABLE 4.1 Continued. *Scaled average length = Nuggfii104egifigrs +Actual length = ScaledOAggga e Len th Where .875 is derived from the scale used. Simple calculations for determination of the weighted average fiber length are given in Table 4.2. The weight of fibers used in each test run, W = 5 gms. TABLE 4.2 WEIGHT 0F FIBERS RETAINED 0N FOUR U.S. STANDARD SIEVES Screen Weight of Fibers Retained on Screen Used gms. #14(1.4lmm.) w1 = .3841 #30(.595 mm.) w2 = 1.0663 #50(.297 mm.) W3 = 1.5486 #100(.149 mm.) W4 = .6016 <#100 w5 = 5—(.384l + 1.0663 + 1.5486 + .6016) = 1.3994 Loss = 1.3994 + 5 27.99 3 28% Weighted average fiber length, L = ££l _(.3841x2.6645)+2.674x1.0663)+(2.0495x1.5486)+(1.1285x.6016)+(1.3994x.1) 5 = 1.5734 mm 72 Figure 4.3a Projected fiber lengths, No. 14 sieve size. Scale: 10111 = 0.875 in. 73 Figure 4.3b Projected fiber lengths, No. 30 sieve size. Scale: 1 mm = .875 in. 75 Figure 4.3d Projected fiber lengths, No. 100 sieve size. Scale: 1 mm = .875 in. 76 4.l.3 Specific Gravity of Pulp Fiber Specific gravity or density of the pulp fibers was determined by the pycnometer method using water as the displacement medium for measuring the volume. Data for six determinations are included in Table A.4 giving an average density of l.5976 g/cm3. This value of density is high because water used as the displacement medium is a polar swelling liquid and has a high capability to penetrate the cellu— lose fiber. A value for the density equal to l.54 (Hermans, l949) is obtained when the displacement medium is an organic liquid such as benzene. The larger organic molecules are unable to penetrate the fiber. The value of l.54 g/cm3 has been used in subsequent calculations for this project. 4.l.4 Surface Area of Pulp Fiber Two methods were employed to determine the surface area of the cellulose fibers. One method consisted of using nitrogen adsorption and the second method employed the use of water vapor adsorption. The results obtained using these two methods were different, l.5 mZ/g for nitrogen absorption versus l33 m2/g for water vapor absorption. Grim (l968) states that the surface area value for montmorillonite determined using water vapor adsorption are much higher than those obtained by nitrogen adsorption, owing to the penetration of water be- tween the basal planes of the montmorillonite units. A comparison of the surface areas for the same clay mineral determined by the two methods is given by Grim (l968). The chemical agents used to give rise to different vapor pres— sures are listed in Table 4.3. Dry pulp fiber samples with known weights were placed in air tight desiccators and subjected to TABLE 4.3 CHEMICAL AG 77 ENTS USED FOR DIFFERENT WATER VAPOR PRESSURES p/p0 Agent Used 0.05 69.44% H2504 0.25 55.01% H2504 0.45 45.4l% H2504 0.66 Saturated NaNO2 0.757 Saturated NaCl 0.930 Saturated NH H P0 424 Room temperature Barometer pressure, pO Density of Hg Density of H20 20°C l7.535 mm of Hg l3.5462 .99823 78 environments of different vapor pressures. The room temperature sat- uration pressure and the related data necessary to calculate the mono- molecular capacity after plotting the B.E.T. adsorption isotherm are given in Table 4.4. Table 4.5 lists the magnitudes of the different terms in the B.E.T. equation with respect to different vapor pressures. Figure 4.4 shows p/p0 on a horizontal scale plotted against water con- tent with respect to the dry weight of the solids on a vertical scale. The curve obtained is similar to the one expected for cotton, since cotton is at least 90 percent pure cellulose (West and Todd, l955). Figure 4.5 provides the basis for determination of the unknown para- meter Un’ i.e., the monomolecular capacity where k is a constant. In this plot of p/p0 versus pfi%(po-p), the intercept l/kvm and the slope of the initial portion of the curve, which should be a straight line due to single layer adsorption, was determined. Using the cal- culated cross-sectional area of a water molecule equal to 10.561?2 gives the specific surface area of l33m2 based on the number of water mole- cules adsorbed by cellulose fibers in a single layer. The following formula (Perkin-Elmer Corp., l96l) was used to determine the cross-sectional area of a molecule of water, 2/3 M 4Na - d/E a1= 4 x .866 (4.1) where a]= cross—sectional area of a molecule of water, cmz, M = molecular weight of absorbate, gm, N Avogadro's no. 6.02 x 1023, density of water, gm/cm3. 0. II 79 .Ammo_:FPoov awn?» a_:m co capo; mo Egmgp0m_ co_pagomc< ¢.¢ mgsmwm - Doom ”mgzpngmasmp OH ma om mm q '1M Kup ‘% ‘paqqospe 4919M SLSP 8O .cmaww n_:a :0 mem3 to ELwcHOm_ :owuagomu< .H.m.m m.¢ mgzmwu 0% a. m. N. w. m. v. m. N. _ _ _ — — — q _ zpwumgwu Lm>c_0coe u E> mczgmcwasmu pcmumcou we mczmmmca :o_pmc:pmm n on mcwn_m gran mo pgmwm2,xLu E avg: ow pumammc cwwz ucwpcoo memz u .m >.x o¢.H u E H n pamocwch E; on E; 2.03””. lsdllldl ooow ”mgzamcmaEmp OH om om ow om ON m_X (d'od) TABLE 4.4 TABULATED VALUES FOR THE B.E.T. EQUATION 8l No. of P P/Po m x 33 33 Samples Dry wt. of Wt. of m m sample Moisture (Average) (gms. gms.) a .8767 0.05 0.37455 .00738 .0l970 b .8767 0.05 0.388ll .00772 .01989 .01953 c .8767 0.05 0.3308l .00629 .Ol90l a 4.3837 0.25 0.23297 .0l057 .04537 b 4.3837 0.25 0.32689 .0l53l .04683 .04624 c 4.3837 0.25 0.2l077 .00981 .04654 a 7.8907 0.45 0.32684 .02l93 .06709 06759 b 7.8907 0.45 0.36054 .02455 .06809 ' a ll.573l 0.66 0.290l5 .02606 .0898l 08925 b ll.573l 0.66 0.27341 .02425 .08869 ' a l3.2739 0.757 0.25087 .02759 .10997 10974 b l3.2739 0.757 0.33080 .03623 .l0952 ' a l6.3075 0.93 0.2557l .05433 .2l246 20599 b l6.3075 0.93 0.26l76 .05223 .l9953 ' Room temperature = 20°C Saturation pressure, p0 = Density of Hg. Density of H20 l7.535 mm of Hg. l3.546 0.9982 82 TABLE 4.5 B.E.T. ADSORPTION ISOTHERM DATA No. p p .Q_ £03513) IDo l 0.88 2.69 0.05 2 4.38 7.21 0.25 3 7.89 12.l0 0.45 4 11.57 2l.75 0.66 5 13.27 28.39 0.757 6 l6.3l 64.49 0.93 Temperature = 20°C Saturation pressure,p0 = 17-535 mm 0f H9- %(p _p) kvm kv po Slope — 40 .28 25, kvm 25 _ _l_.= 1.4 Intercept — l.4 kvm vm = .03787 and k = l8.857l 83 The molecular weight of water is l8 grams per mole and there are 6.02 x 1023 water molecules in one mole, hence 2/3 a = 4 x .866 1823 ___ 4 x 6.02 x l0 x .99823 /2 2 2 l0.56 x 10'15 cm = l0.56 A From the slope of the B.E.T. curve, Figure 4.5, the monomolecular capacity vm equals 0.0378 and the number of water molecules in this monolayer capacity therefore equals, 23 6'02 T810 x .0378 = l.26 x lOZ] molecules and the specific surface area = (l.26 x l021)(l0.56 x l0'16)/l002 l33 mz/dry gram of cellulose. 4.2 Compression Tests Compression tests on fiber/kaolinite samples of varying composi- tion were conducted in one dimension, the load approaching 360 kg/cmz. Samples tested included those made from fibers, 25 percent fibers/75 percent kaolinite by volume, 54 percent fibers/46 percent kaolinite by volume, and kaolinite. 4.2.l Kaolinite Compressibility characteristics of kaolinite samples were studied by confining the soil sample in directions at right angles to the axis of controlled stress application. This is similar to the condi- tions in natural soil strata, one dimensional deformation in the direction of the principal applied stress. This compressive deformation 84 is expreSSed interms ofthe soil void ratio, hence the results are referenced to a scale which is independent of the size of the specimen tested (Scott, l963). The void ratios corresponds to equilibrium conditions with respect to the applied stresses, that is the stable condition achieved by interparticle contact for a given load. The effective normal stresses are plotted on a horizontal scale against the equilibrium void ratios on a vertical scale in Figure 4.6a. The initial larger deformations occur as a result of grain movements or adjustments between particles. As the stress increases these move- ments decrease as the grains settle into more stable positions. With increase in vertical stress a large proportion of the movement appears to be due to elastic compression (Scott, l963) of the grains. Figure 4.6a shows that the initial part of the diagram is curvilinear whereas the part corresponding to high stress levels is approximately a straight line. At a stress level of 2.40 kg/cmz, which is the con- solidation load of the sample, the void ratio was l.l89. This void ratio for pure kaolinite is relatively high suggesting that the particles of clay are randomly oriented. At a stress of 330 kg/cm2 the void ratio decreases to a value of 0.50 suggesting a denser struc- ture in which the clay particles have perhaps achieved a more orderly arrangement. The straight line portion has a gentle slope indica- ting a small change in void ratio corresponding to a relatively large change in the applied normal stress. The normal effective stress on a logarithmic scale is plotted against void ratio on a natural scale in Figure 4.6b with a straight Void ratio, e Void ratio, e 85 Sample C4 (60 W 1 l L L L L J 50 100 150 200 250 300 350 Effective normal stress, kg/cm Sample C4 ( b ) 2 l— ; \\\" * 1 J 1 10 100 1000 Effective normal stress, kg/cm2 Figure 4.6 Effective normal stress (Natural and logarithmic scale) vs. void ratio curves for Kaolinite samples. 86 line drawn through the data points. This straight line relationship is common for dispersed clays. 4.2.2 Kaolinite-Fiber Mixtures Samples subjected to compressibility tests were prepared from l) a mixture of 54 percent fibers and 46 percent kaolinite by volume and 2) a mixture of 25 percent fibers and 75 percent kaolinite by volume. Effective normal stress is plotted against the corresponding equilibrium void ratio in Figures 4.7a and 4.8a. The initial part of the curves corresponding to relatively low normal effective stresses ‘ are curvilinear whereas at higher normal effective stresses they dis- play approximately a linear relationship between the normal effective stresses and the corresponding void ratios at equilibrium. The normal effective stresses are plotted on a logarithmic scale against the corresponding void ratios at equilibrium on a natural scale in Figures 4.7b and 4.8b. The behavior indicated by the curvilinear nature of these plots is similar to the behavior expected from a floc- - culatedaelay (Scott, l963) subjected to the same type of compression test. Theradius of curvature of these curves appear to decrease with increasing fiber content in the test sample. 4.2.3 Fiber Samples All fiber samples were subjected to compression tests in a manner similar to those for kaolinite and mixed samples. The void ratio-stress curves for all fiber samples are shown in Figure 4.9. The shape of the curve in Figure 4.9a is similar to the curve shown 87 4.. Sample C2 0) 3i... .9? 4.: ‘s‘.’ 2 (a) 'U .8 1— > 1 L I 1 l I I 0 50 100 150 200 250 300 350 Effective normal stress, kg/cm2 4r Sample CZ CD .6? E 2__ (6) 3° 8 > L I I 1 10 100 1000 Effective normal stress, kg/cm2 Figure 4.7 Effective normal stress (Natural and logarithmic scale) vs. void ratio curves for 54% fiberS/45% Kaolinite samples (by volume). 88 Sample C3 Void ratio, e N l E? I l l l 4_J 0 50 100 150 200 250 300 350 Effective normal stress, kg/cm2 4T w Sample C3 .2” E 2" (b) 3° é l l I 1 10 100 1000 Effective normal stress, kg/cm2 Figure 4.8 Effective normal stress (Natural and logarithmic scale) vs. void ratio curves for 25% fibers/75% Kaolinite samples (by volume). Void ratio, e Void ratio, e 89 Sample C1 H O 50 100 150 200 250 300 Effective normal stress, kg/cm2 Sample C1 .fi I N l l 1 _ 1 10 100 Effective normal stress, kg/cm2 Figure 4.9 Effective normal stress (Natural and logarithmic scale) vs. void ratio curves for all fiber samples. 350 1000 90 TABLE 4.6 SUMMARY OF COMPRESSION TEST DATA Test Sample Compression Final Void Coefficient of No. Composition Load Rati0' Vol. Com resibility (% by Vol.) (kg/cmz) (cm /kg) 6.3974 2.4383 980 x 10'4 _4 c1 l00%F* 43.8087 0.99l6 156.42 x 10 171.6723 0.5285 43.10 x 10-2 360.2678 0.3588 21.22 x 10‘ 6.3975 1.6886 558.04 x 10:2 02 54%F + 46%C 42.4974 0.8948 112.82 x 10 170.3610 0.5449 32.95 x 10-2 358.9199 0.4127 16.59 x 10' 6.4315 1.3344 384.65 x 10:2 03 25%F + 75%0 42.0928 0.8159 86.33 x 10:4 169.9563 0.5527 26.13 x 10_4 358.5245 0.4344 13.49 x 10 6.3975 1.0123 202.41 x 10:2 04 100%c* 42.0338 0.7403 51.75 x 10_4 169.8974 0.5720 16.83 c 10_4 358.4202 0.4791 9.11 x 10 *F = Fibers c = kaolinite 91 in Figure 4.7a for the fiber/kaolinite mixture. At a consolidation pres- sure of 2.40 kg/cm2 the void ratio of 4.65 (Figure 4.9a) was the highest compared to the void ratios obtained for previous fiber/kaolinite samples at the same level of normal effective stress, however, the void ratio decreased more rapidly with increasing stress. Note that all fiber samples display consistently higher void ratios compared to all other test samples as long as the normal effective stress level was less than approximately ll8 kg/cmz. A summary of compression tests is pre- sented in Table 4.6. 4.3 Direct Shear Tests Samples subjected to direct shear tests were prepared from full length fibers and powdered fibers. Tests were carried out on saturated and dry fiber samples. 4.3.l Saturated Fiber Typical curves for direct shear tests on a saturated fiber sample are shown in Figure 4.l0. Shear displacement is plotted against shear stress and vertical displacement. Failure was arbitrarily assumed at 20 percent strain since the material exhibits a continuous increase in shear strength with increasing displacement. The behavior of a saturated fiber sample subjected to two cycles of loading and unloading is presented in Figure 4.lla with shear dis- placement plotted against shear stress and vertical displacement. Each cycle of load produces permanent strain as shown by the two intercepts on the horizontal axis. Figure 4.llb shows the change in the vertical displacement caused by the cyclic load. The variation of water content with consolidation pressure for saturated fiber samples is summarized in Figure 4.l2. 92 3— (”a - Shear test S6 3 3 2 u? (A 2 if, L 1 f6 <1) .2 V) l L L I I 0 1 2 3 4 5 Vertical displacement, mm Figure 4.10 Typical Shear displacement vs. Shear stress and Vertical displacement curves for saturated fiber samples. Shear stress, kg/cm2 0 O O O 0 Vertical displacement, mm 0 93 51‘ Shear test 52 -V— Loading (a) V V’ 4 .— "<>"Unloading 3 ” Loading . Unload1ng ‘V ZF' ‘I V’ V’ 1- v. I I I O 1 2 6 Shear displacement, mm 0 1 2 3 4 5 6 1 2 Unloading ‘-—W\§D/ Figure 4.11 Shear displacement vs. Shear stress and Vertical dis- placement curves caused by two cycles of loading and unloading a fiber sample. 94 300- Shear tests 31 through S9 250 200' 150 " V Water content, % 100 Consolidation pressure, kg/cm2 Figure 4.12 Consolidation pressure vs. final water contents for saturated fiber samples. 95 4.3.2 Dry Fiber Two types of dry fiber samples, one oven dried (hard cake) and the second prepared from freeze dried fibers, were subjected to direct shear tests. The results obtained for the two sample types were ex- pected to be different due to the difference between their physical characteristics caused by the methods used to dry the fibers. Consolidation pressure is plotted against void ratio for dry and saturated fiber samples in Figure 4.l3. The dry fiber samples consistently maintaineda higher void ratio than the saturated fiber samples for the same consolidation pressure. Horizontal displacement is plotted against shear stress and vertical displacement for a sample composed of dry powdered fibers in Figure 4.l4. The continuous increase of shear strength with in- creasing lateral strain is shown in Figure 4.l4a. The decrease in sample volume with increasing lateral strain is shown in Figure 4.l4b. Shear displacement is plotted against shear stress and vertical displacement for an oven dried sample composed of all fibers in Figure 4.l5. The behavior of this sample was quite different from that observed for the dry powdered fiber sample. The shear strength of the sample increased rapidly with a small increment of strain and the sample failed suddenly at approximately l2 percent strain (Figure 4.l5a). Sudden rupture was perhaps due to the fracture of the bond between the fibers in the case of the oven dried sample. The sample exhibited an increase in volume with increasing lateral strain (Figure 4.l5b). A summary of the direct shear tests conducted on dry and saturated fiber samples is presented in Table 4.7. Void Ratio, e 96 6.. Dry samples 512 through 318 5.. 4.- 3— Saturated samples S20 throu h 525 V v 9 2.. 1 I l I L L I 0 1 2 3 4 5 6 2 Consolidation pressure, kg/cm Figure 4.13 Consolidation pressure vs. Void ratio curves for saturated and dry powdered fiber samples. 97 Shear test 511 Dry powdered fiber sample Shear stress, kg/cm2 J I 6 7 Shear displacement, mm 3 0 1 2 3 4 5 6 7 . 1 r 1 1 I 1 4..) C ‘120.1 - OJ 3 (b) 220 2 - ... V :03~ v "'- (O U 2:0.4 1- S. (I) > Figure 4.14 Typical Shear displacement vs. Shear stress and Vertical displacement curves for dry powdered fiber samples. 98 Rupture with decreasing load 8 _ NE 6- U \ j? Shear test 810 J; 8 4 5... +9 03 S. 8 5. 2 (a) O. -1 0 .1 '3 Shear displacement, mm Vertical displacement, mm Shear displacement, mm Figure 4.15 Shear displacement vs. Shear stress and Vertical dis- placement curves for an oven-dried fiber sample. 99 nopmczwmm mm.mm om amm_.m emm._ mm.¢m mm_ vmm.P omm = mo.~¢ ow camp.“ omm.o ¢F.¢~ --- omm.o m_m = Km.m¢ ON movm.m omm.¢ m¢.NN --- mmo.¢ mpm = mm.vq om NmNo.¢ .mNo.¢ mN.Fm --- mmo.¢ Rpm = m~.wv om mmum.m Nm¢.m Pm.om --- Nm¢.m cpm = mm.w¢ om mF—N.m mm.m mm.mp --- mm.m m—m = om.mm om.om omPo.m P~.N m—.mF --- _N.N ¢~m = om.Pm om moo.m «mm._ mo.mp --- vmw.~ mpm = _m.mm om PPmN.P mom. om.¢F --- mom. NFm mpqsmm away; xco em.mm om oqmw.m _N.N .m.: --- om.m _Pm mpaawm , umvgv cm>o mm.¢~ NF Nmmm.~ PN.N Pm.mF co.omm RN._ opm = mm.om om ammo.m _N.N No.5N oo._op _N.m mm = m_.~¢ om omom._ mm.~ mm.mm oo.mom mm.F mm = mm.o¢ om mpvo.m m¢.m mo.m~ oo.mm_ m¢.m Rm = o~.m¢ om ompm.w _N.N N_.mm oo.¢- _N.N mm = mm.m¢ om NN¢P.F om. mo.m. oo.mmm mm. mm = mm.om om.om mmvm.P mm._ N¢.mm oo.~om mm._ em = mw._m om weep.m mo.¢ mp.mm oo.m- mo.¢ mm mFQEmm umamczpmm mm.m¢ om ommo.¢ mq.m mv.om oo.o¢_ m¢.m mm mpgamm umpmczwmm w~.om om Nmo¢.m mw.m. Nu.Pm om._mp mm.N Pm Ammmcmmov Ax V ANEo\mxv >ANEU\me Aeoav “xv Amso\m¥v am acmemum_amwa wczpvwm um w am mmmcum Xpwmcmo “caucou ogzmmwca m—Qsmm mxgcamm Mpucmuue mcap_mm mmmcum cmmcm FmELoz «xco «Lopez :owpccwpomcou amok mhgzmmm Hmmh mmw poz u .w.: = om.m¢ om opoo.m eom.m FN._m Nm_ vom.m mmm = mo.~¢ om ome.N omm.m mo.mm NP_ omm.o «mm = . NN.m¢ om Nmop.¢ mxo.¢ N_.wm um, mko.¢ mum = ~¢.m¢ om «opm.m omm.m ao.om mNP omm.~ Nwm cmpmgspmm mo.Pm om momm.m mom.m mw.um mm_ mom.m pmm Ammmgmmov Axv A EU\me ANEU\me Amoav ARV A~50\m¥v >w “cosmom—amwa mgspmmu pm.e >H mmwgum xuwmcmo ucmucoo mczmmmgm m_asmm mxcmEma H1. coaue mc=__mu mmwgum gwmgm IFmELoz exec xcmumz :o_gmuw_om:ou “map I. —-II Aumzcwacouv n.¢ MAm mgzmmmca cowumwwpomcou NH.¢ mczmwu EU\mx .mczmmmca :owumu_F0mcoo N N o m e m m a o - q a d a (q 41 tom low Loo ‘1ua3uoo J819m a lo i ”um-mk‘c -.. — ' 104 3 F CVE Sample No. CU-3 ii 2 Kaolinite 2 i? Consolidation pressure = 5.5 kg/cm Am '? L3H 1 L 1 L 1 1 0 2 4 6 8 10 12 4.. N 3" E . ii 3 2- :; «a 1- (b) L 1 L 1 L J , o 2 4 6 8 10 12 A factor Axial strain, % Figure 4.18 Axial strain vs. effective deviator stress, pore pres- ‘ sure and pore preSsure coefficient, A, curves for Kao- linite sample CU-3. 105 3— Sample No. CU-7 Kaolinite 2 °fl5 Consolidation pressure = 2.50 kg/cm 3 U3 A4 ’?6 Au, kg/cm2 H l 1 1 I 1 1 J 1 0 2 4 6 8 10 12 14 1 L O E» .5 “— (C) < I I I I I I I 0 2 4 5 8 10 12 14 Axial strain, % Figure 4.19 Axial strain vs. effective deviator stress pore pres- sure and pore pressure coefficient, A, curves for Kao- linite sample CU-7. lO6 is shown in two typical plots with percent axial strain plotted against deviator stress (51 - 53), pore pressure Au, and the pore pressure coefficient A are shown in Figures 4.l7, 4.l8 and 4.l9. These figures represent kaolinite samples normally consolidated to pressures of 5.50 kg/cm2 and 2.50 kg/cm2 with failure at 9.2 percent and 11.3 percent axial strain, respectively. The pore pressures in both cases increased rapidly during the early part of the test and leveled off as failure was approached. Pore pressure values at failure were 3.06 kg/cm2 (Figure 4.l8b) and l.33 kg/cm2 (Figure 4.l9b). The pore pressure coefficient A increased rapidly at low strain values, then leveled off with final values of l.03 and 0.79, respectively, for the two tests. 4.4.2 Kaolinite/Fiber Mixtures The kaolinite/fiber mixtures included two combinations, 54% fiber/46% kaolinite and 25% fiber/75% kaolinite by volume. Triaxial tests first involved preparation of a mixture of kaolinite and fiber into a high water content slurry which was consolidated into 200 mm high by l00 mm diameter cylinders. Using a high speed l9 mm diameter circular saw, test specimens 76 mm high by 38 mm in diameter were cut from the larger sample. After placement in the triaxial cell samples were consolidated to a slightly higher pressure. Next a back pressure was applied to the sample in order to achieve a high degree of saturation. Consolidation pressures ranged from l.5 to 6 kg/cm2 for the triaxial samples. Six complete triaxial tests were conducted, three consolidated drained and three consolidated undrained, on the 54% fiber/46% kaolinite mixtures. Water contents following consolidation lO7 are summarized in Figure 4.20 for all the tests. Typical curves showing deviator stress, pore water pressure, and the pore pressure coefficient A, all plotted against axial strain for an undrained triaxial test are shown in Figure 4.2l. Axial strain was extended to 20 percent so as to permit definition of failure at this value of strain or by the maximum ratio of shear stress to effective normal stress described in a later seCtion. The continuous increase of the deviator stress with increasing strain is shown in Figure 4.2la. The pore pressure value corresponding to 20 percent axial strain equals 2.86 kg/cm2 in Figure 4.2lb and the pore pressure coefficient A equals 0.63 in Figure 4.2lc. Typical curves for the consolidated drained triaxial tests, are shown in Figure 4.22 where percent axial strain is plotted against the deviator stress (61 - 53) and the volumetric strain $%-. The change in volume is AV with the initial volume equal to V0. Figure 4.22a shows a continuous increase of strength with increasing strain, hence failure was assumed at 20 percent axial strain. The relationship between the axial strain and the volume change of the sample is shown in Figure 4.22b. Kaolinite-fiber samples with 25 percent fibers and 75 percent kaolinite by volume were prepared in the same manner as described for fiber-clay mixtures in section 4.4.l. Seven triaxial samples were tested, fourconsolidated undrained and three consolidated drained. The consolidation pressures used, ranged from a minimum of 2 kg/cm2 to a maximum of 6 kg/cmz. Prior to application of the deviator stress, back pressures were used in an attempt to insure saturation and to deair the space between the rubber membrane and the sample. 108 .AmE=_o> any mmpaamm mu_=ppoe¥ ame\mgmn_g aqm gee m>e=u ucmucoo gout: .m> mgzmmmga :o_uev_~omcou om.¢ mczm_u ~56\mx .mezmmwea :oPpec__om:ou o m c m N H a q - a _ — — mszpo> An mu_:wpomx fine L \mgmaww gem Lo mmPQEem ummp cmueu__omcoo om cm as ow ‘1uaquoo J819M % 109 5 - (\IS 4 - E5 3 Sample No. CU-CFZ “ 54% fiber/46% Kaolinite ,i (by volume) .67 2 Consolidation pressure = L. 4.00 kg/cm2 '3 1 (a) L I L I J 0 5 10 15 20 25 N E U \ C5 .54 5‘ < . I 25 1. S. O t; 5 ‘3 1c) ‘5 JL 1 L 1 0 5 10 15 20 25 Axial Strain % Figure 4.21 Typical results from a normally consolidated undrained triaxial test on 54% fiber/46% Kaolinite (by volume). (a) Deviator stress (b) Pore pressure change (c) Change in parameter A. 110 10’ Sample CD-CFl Consolidation pressure = 4.5 kg/cm2 N E U \ 03 .32 Am 1 D I Lev—1 J I l 4 1 0 5 10 15 20 25 Axial strain, % 25 .1 A! Vo Figure 4.22 Typical results from a drained triaxial test on 54% fiber/ 46% Kaolinite (by volume). (a) Deviator stress (b) Volume change. 111 .Ams:_o> Any mm_asmm mpwcwpomx xmk can meanwe xmm Lo; ucmucoo Lopez .m> mezmmmga cowumu__om:ou mm.¢ weaned NEU\mx .mczmmmcg co_ueu__Om:ou m o m e m N H o _ _ _ _ _ _ _ Av AV 1 ow D D D 4 cm 100 Aee=_e> any eeee__ee¥ Rm“ \Lma_w amm 4o mm_QEmm “may cmumu_POm:oo 1 cm % ‘3ua1uoo 4819M 112 47 Sample No. CU-FC4 ' 75% Kaolinite/25% fiber (by volume)2 ). kg/cm2 A I .6“ Consolidation pressure = 6.00 kg/cm .512 ‘ (a) I I I I L I 1 0 2 4 6 8 10 12 14 5 r Au, kg/cm2 14 l 5.. 437—- *3 5 .2 ' (C) < I l ' I I L I J O 2 4 6 8 10 12 14 Axial strain, % Figure 4.24 Typical results from a normally consolidated undrained triaxial test on 25% fiber/75% Kaolinite (by volume) (a) Deviator stress (b) Pore pressure change (c) Change in parameter A. ). kg/cm2 “1'“3 ( 113 8 _ Sample CD-FCl Consolidation pressure = 4.0 kg/cm2 6 4 (a) 2 I I I I I 0 5 10 15 20 25 Axial strain, % 0 10 15 20 25 r l T I l .1 - (b) .2 b Figure 4.25 Typical results from a drained triaxial test on 25% fiber/75% Kaolinite (by volume). (a) Deviator stress (b) Volume change. ll4 The variation of water content with consolidation pressure is shown in FigUre 4.23. Water contents ranged from a minimum of 40.5l percent to a maximum of 5l.05 percent corresponding to consolidation pressure of 2 kg/cm2 and 6 kg/cmz, respectively. Typical curves for the con- solidated undrained condition with axial strain plotted against the deviator stress (61 - 53), pore pressure Au, and the pore pressure coefficient A are shown in Figure 4.24. Failure occurred at a deviator stress of 4.759 kg/cm2 corresponding to a strain of 8.807 percent (Figure 4.24a). The sample, even though a mixture of fiber and kao- linite, exhibited a brittle type of failure. This behavior may be due to the presence of a high percentage of kaolinite. Figures 4.24b and 4.24c show the pore pressure and the pore pressure coefficient A at failure as 3.48 kg/cm2 and 0.73, respectively. Typical data for consolidated drained triaxial tests on the 75% kaolinite/25% fiber samples are shown in Figure 4.25, where percent axial strain is plotted against the deviator stress (51 - 53) and the volumetric strain given by the ratio 96"“ The initial sample volume after normal consolidation is designated by Vo where AV denotes the change in volume of the sample during the time when the deviator stress was operative. ,The sample showed a continuous increase of strength with increasing axial strain (Figure 4.25a), hence failure was assumed at 20 percent axial strain. The relationship between axial strain and volume change is shown by Figure 4.25b. 4.4.3 Fiber Samples Fiber samples were prepared in a mold approximately 76 mm high by 38 mm in diameter by pouring a cellulose/water slurry directly into ll5 the mold in small quantities. Excess water was allowed to drain and ' more slurry was added. Small quantities of slurry were used for each increment so as to minimize any layering effect. This method for preparation of fiber samples was ad0pted due to the difficulty involved in cutting the soft fiber test specimens to the desired dimensions from a larger cylinder. After placement in the triaxial cell, samples were normally consolidated to the desired pressures. Next a back pressure was applied to the sample in order to achieve a high degree of saturation. The measured pore pressure coefficient 8 was consistently below unity due to trapped air in the voids of the fiber structure with the B parameter ranging from .80 to .90. The computed pore pressure coefficient A values at failure had a range from .20 to .72 with an average of .57. The water content ranged from about l00 to l50 percent for con- 2 2 as shown in solidation loads ranging from l.5 kg/cm to 4.5 kg/cm Figure 4.26. Typical data for a sample subjected to consolidated un- drained triaxial test conditions with pore pressure measurements are shown in Figure 4.27 where axial strain is plotted against the deviator stress (61 - 63), pore pressure Au, and the pore pressure coefficient A. Since the material displays a continuous increase of strength with increasing strain (Figure 4.27a) failure was assumed at an arbitrary value of 20 percent axial strain. In the case of undrained tests on all fiber samples, the calculated stresses corresponding to 20 percent strain are questionable since the pore pressure increases to the cell pressure (Figure 4.27b) at an axial strain less than 20 percent. The [Dore pressure value measured at l8.66 percent axial strain was 2.5l 116 .mm_qsem emcee toe acmpcoo cmumz .m> mezmmmca :oepenwpomcou mN.¢ «gamed NEo\mx .mezmmwca cowwmuw_omcou m e m N H o _ 1 . a . tooH IOmH L_oom % ‘1uazuoo 4318M 117 Sample No. CU-Fl 2 Consolidation pressure = 2.5 kg/cm 6‘ All fiber N 5 \ 4" U) x ’7». "3 1972" §7 I 0 5 10 15 20 25 . 4P (\I E U \ 3 2- g‘ (b) I I I I 1 0 5 10 15 20 25 L 1 . O 5 5 “,3 . We) < 1 1 1 1 1 0 5 10 15 20 25 Figure 4.27 Typical results from a normally consolidated undrained Axial strain, % triaxial test on a fiber sample. (a) Deviator stress (b) Pore pressure change (c) Change in parameter A. 118 10 r Sample CD-F5 2 Consolidation pressure = 4.50 kg/cm All fiber 8 N E U \ U? .32 Am '34- (61) L3 I I L L I 0 5 10 15 20 25 Axial strain, % 25 I .21 V0 Figure 4.28 Typical results from a drained triaxial test on a fiber sample. (a) Deviator stress (b) Volume change. 118 10 _ Sample CD-FS 2 Consolidation pressure = 4.50 kg/cm All fiber 8 (\I E U \\ D? .32 Am ”C..- (a) 13’ L I 20 25 25 I .91 V0 .2 - Figure 4.28 Typical results from a drained triaxial test on a fiber sample. (a) Deviator stress (b) Volume change. 119 6 .— Sample CD-F6 2 Consol1dat10n pressure = 1.5 kg/cm >5 4 gumcwcpm xgwmcwo pcmpcoo , mezmmmea cowpwmoqsoo xmo ._o umcwegucz zen Loam: cowueuwpomcou mPQEmm meosmmm emme Am e < x mFaep_m>m ac: u .e.= vmcwecv umumcwpomcou u no casemevcz empeuPPOmcou u so cmn_m n m mgwcwpomx u u x om.o No.o Nmo.¢ moo.N ON.mN Fm.mm_ mo.N LNOOF Nmuzu mm.o o.o ocm.F No.o .e.: .m.: oo.P LNooF amino mm.o o.o mFN._ mmm.o om.ON ov.¢mN oo._ LNooF muuau NN.o mm.o mmm.¢ va.N m_.om mm.mmp om.m LNOOF «Luau mo.o oo.o NNN.o Nmm.o oo.mp Po.mmN om.o mNooF manna oN.o em.o oNF.P mmm.o o_.m_ ww.o¢N om.o LNOOF Nu-:o mm.o o.o omm.¢ moN.N mm.mN mN.m¢F om.N mNoop ”also 1.. om.~ me.¢ ovN._ mm.NN NN.omF om._ LNoop amino --- om.¢ Nm~.mp on.¢ mm.mm mo.cm om.¢ LNOOF mmuou --- oo.m mNP.m Noo.m om.Pm _m.w__ oo.m LNoop «Luau --- om.¢ oqN.mF ONc.¢ mN.mm Np.ooF om.¢ mNoop mm1au --- oo.m mmm.op mNm.m No.mm NN.m_P oo.m LNoo— NL1oo --- om.F Nmo.m was.” mo.mN mm.¢¢P om.~ mNooF Fuuou --- om.N oN_.m m_w.N «N.mm mn.mm Om.N uxcm+oxc¢ mmouou ANEo\mxv ANEo\mxv ANEU\me Amogv ANV ANEu\mxv mszpo> an e. e zumcwcpm zuwmcmo “cmpcoo mczmmmga cowuwmoaeou mFQEem. xm< mm ._@ umcwmgvca xgo Lopez cowueuwpomcoo «Fasmm ummh Avmzcwgcouv m.¢ m4m

Charlie, 1975 C) Laza, l97l I ‘r <> ‘f .75. +, 5 l '5 2: 1.... OJ 8 .50-. <3 OJ L- 3 m (.0 Q) S- D. 2 .25- O Q. 0 20 40 60 80 100 % fiber by volume r r I r T 1 I T I T 1 O 20 40 60 80 100 % fiber by weight FIQUPG 4-31 Influence of organic (fiber) content on the pore pressure parameter A at failure in triaxial tests. CHAPTER V DISCUSSION AND INTERPRETATION OF RESULTS This discussion and interpretation of project data is presented in four sections: physical properties, compressibility of the kaolinite/ fiber mixtures, shear strength of kaolinite/fiber mixtures, and impli- cations for stability problems. 5.l Physical Properties The initial part of this section describes the fiber structure and shape as seen through a scanning electron microscope. The latter part of the section appears under a heading of kaolinite/fiber mixtures. 5.l.l Fiber Size, Shape, and Structure Fiber size, shape, and structure is not readily apparent to the unaided eye. To obtain a better understanding of the fiber material, photographs shown in Figures 5.l, 5.2, 5.3 and 5.4 were taken using a scanning electron microscope. The fiber sample must be dried before exposing it to the scanning electron microscope. Cellulose fibers shown at l20 magnification in Figure 5.lb resembles grass blades. The cross-section of a single cellulose fiber is magnified 2000 times in Figure 5.la. An elongated hole appears to extend through the body of the fiber. A single fiber magnified 2000 times in Figure 5.2a has an average dimension on the photograph equal to 53 mm. One micron magni- fied l000 times will equal one mm on the photograph, therefore, ID .053 -:- 2000 x .00002 meter = .00002 x 10 A =200,000}i = 20 micron. l26 127 (b) Figure 5.1 (a) 2000 magnification of the cross section of a single pulp fiber (b) 120 magnification of several pulp fibers. 128 (b) Figure 5.2 Surface characteristics of cellulose pulp fibers, 2000 magnification. 129 (b) Figure 5.3 Fiber-clay particle size comparisons, 1000 magnification 130 (b) Figure 5.4 Scanning electron microscope photographs, 10000 mag- nification. (a) Cellulose pulp fiber. (b) Kaolinite particles. l3l In a cotton fiber there are approximately 1500 fibrils and each fibril has an approximate area of 0.l6-u2 (Denlin, l966). Therefore the approxi- 2 = 2401.2. mate cross-sectional area of a cotton fiber equals l500 x 0.l6u Assuming a circular cross-section, 2—d2 = 240u2, or d = l7.4811=:l8u. The l811is in approximate agreement with the calculated value of 20p. Assuming that the average lateral dimension of a single fiber is about 20p, the larger dimension of the hole in Figure 5.2a is about l5u and the smaller dimension is about Zn. The size of the hole in Figure 5.la is approximately 4p x l2u. A sample composed of all fiber would be resilient, especially if the fibers are dry since the addition of water significantly enhances their compressibility. A saturated sample would be expected to be resilient at very high stress levels. The size comparison of kaolinite and fiber particles is shown in Figures 5.3a and 5.3b. A small portion of pulp fiber and kaolinite particles magnified l0,000 times are shown in Figure 5.4. Particle "m" and "n" with dimensions l5 mm and I9 mm, respectively, on the photographs give particle sizes of .015 7 6 10,000 = l5 x l0 m x l0 = l.5u .019 = -7 6 _ W I9 X I0 m X I0 - I.91,1 The calculated dimensions for the two particles satisfy the soil mechanics definition for clay particles with a maximum size of 20. 5.l.2 Kaolinite/Fiber Mixtures The physical properties of kaolinite/fiber mixtures change in proportion to the amount of each component present. The specific l32 gravity of kaolinite particles was 2.65 compared to l.54 for the much lighter cellulose fibers. A simple proportion in terms of the ratio kaolinite by volume, Xk’ can be used to calculate the specific gravity, G, of the mixture, thus G = (l - X l.54 + 2.65 Xk (5.l) k) The weight-volume relationships from soil mechanics can now be used to calculate unit weights, void ratios, water contents, and degree of saturation. The influence which organic (fiber) content has on the mechanical properties is notsimple. The surface area per gram of fiber solids was measured at l33 1112 when both external and internal surfaces are considered. Compare this to an approximate value of If mZ/g for kaolinite. One gram of cellulose occupies a larger volume due to the lower specific gravity and the presence of internal cavities. Also, cellulose is hydrophyllic, that is it has a high water holding capacity as compared to kaolinite. . This hydrophyllic property of cellulose gives it a high swelling potential. MacFarlane (l969) reports that water contents for fibrous peats vary between 750 to l500 percent by weight. A small percentage of inorganic material in the peat sharply lowers this natural water content. In the same manner, the mixture of kaolinite with fiber alters the water content for a given load. For the saturated condition, change in water content also changes the Void ratio. The water holding capacity, or void ratio, will take on increasing values for higher organic contents at the same load. This l33 phenomenon has been shown by Laza (l97l) and in Figure 4.l3. An increase in organic content requires that a larger load be placed on the sample in order to maintain the same void ratio. This becomes a significant factor relative to compressibility of the kaolinite/fiber mixtures and is discussed in a later section. The compressible structure of the fibrous material means that 'large strains are needed to mobilize shearing resistance. The peak stress difference continued to increase up to and above 20 percent axial strain for the 60% kaolinite/40% fiber mixtures by weight (Figure 4.2l) and all fiber samples (Figure 4.27). Fibers l.6 mm in length go into tension along the failure surface as shown by a photo- graph presented by Charlie (l975). The mechanical reinforcement of soil by plant roots has been described by Gray (l974). The shear strength was increased by an apparent increase in cohesion with little effect on the friction angle. Decomposition of the organic (fiber) material has not been con- sidered-as a variable in this study. Natural organic soils including peat, muskeg, or fibrous papermill sludge would be in some state of decomposition. Gray (l974) reports that gradual. decay in root systems leads to a decrease in strength. This effect may possibly be simuIated by kaolinite/fiber mixtures with lower fiber contents. A concurrent study presently in progress is studying the decomposi- tion effects on engineering properties of kaolinite/fiber mixtures. 5.2 Compressibility of Kaolinite/Fiber Mixtures One dimensional compression and triaxial compression of samples with various organic (fiber) contents is discussed. The coefficient I34 of compressibility for the soil structure and the solids are considered in a review of the application of Terzaghi's effective stress concept to organic soils. 5.2.l One-Dimensional Compression Consider a saturated soil element whose sides are subjected to constant external total stresses. A change in the magnitude of pore - pressure will cause a change in the effective stresses at a point on a given plane. For one-dimensional compression the total stress on the top and bottom faces of the element will be different from the stress on the other faces. The increase or decrease in pore pres- sures will cause changes in the effective stress components to which the soil skeleton is subjected. The stress at a point will also change with orientation of the plane passing through the point, hence the description of the change in void ratio in such a system is very complex and only a simplified discussion of the problem is given here. The variation of water content with variation in sample composi- tion is shown in Figure 5.5 for the same final compressive load of about 358 kg/cmz. The greater water holding capacity due tohigher organic contents is apparent. Consider the all fiber sample. When each of the OH groups in cellulose (C6H1005) is hydrogen bonded to one molecule of water, that is when cellulose is fully hydrated there are three water molecules for each cellulose unit and the hydrated formula becomes (C6H1005) - 3H20. One mole of dry cellulose weighs l62 gm and three moles of water weighs (3 x l8) = 54 gm, therefore, the water content of fully hydrated cellulose would be (54/l62)l00 = 33.33 percent (Skaar, l972). The water content of the all fiber sample 135 100 F Final water content after the compressibilityztests. Stress = 360 kg/cm 80 ' 4.1 .2 03 '8 3 j; 60 — 3Q . +: C .8 c 40 _ O U S. .3 (U 3 20 z, . [__. 1 1 1 1 1 0 20 40 60 80 100 Fiber, % by volume 1 1 [II'I III 0 20 40 60 80 100 Fiber, % by weight Figure 5-5 Final water contents after one-dimensional loading to about 360 kg/cm2 for kaolinite, two kaolinite/fiber mixtures, and fiber.samples- ~ I36 after being loaded to a compressive stress of 360.26 kg/cm2 in Figure 5.5 was 42.l3 percent. This is higher than the fully hydrated moisture content, hence the number of molecules of water attached to the fibers is greater than three. The number of water molecules present in the all fiber samples may be estimated. For example, x/l62 = 0.42l3 and x = 68.25. The number of molecules equals 68.25/l8 = 3.79 or approxi- mately 4. The data show that it is extremely difficult to remove the first layer of water molecules from the cellulose fibers by mechanical means. Effective normal stresses are plotted against the equilibrium void ratio on a natural scale in Figure 5.6 for kaolinite, kaolinite/ fiber mixtures, and all fiber samples. Note that all curves have a common point of intersection. The immediate region surrounding the intersection point is shown to an exaggerated scale in Figure 5.7. the normal effective stress is plotted on a logarithmic scale against the equilibrium void ratio on a natural scale in Figure 5.8. The plot for kaolinite shows a straight line whereas the radius of curva- ture of plots for other samples decrease with an increase in fiber content. Note that all fiber samples continued to show the larger change in void ratio at stress levels above the common point of inter- section (Figure 5.7). The behavior of the fiber and kaolinite/fiber samples resemble to some degree the behaVior of floculated clays (Scott, l963) where the void ratio-logarithm of pressure curve is concave upwards. The change in void ratio is most probably due to two phenomena: l) Squeezing of water from between fibers resulting in a 137 . .mwpaEcm mu_=_—oe¥.__m vce .wpwcwpoex Nm¢\mcm _ mu_=__om¥ Nmuxewn_m NmN .gmn_e __e com mm>czo o_uce nwo> .m> mmmepm Pesto: w>mwwmmww c.m mczmpm Eo\mx .mmmcum Peace: m>wgomeem moe 3mm 03m NomN com omfi OOH om o _ — _ _ lixori. . , - ..om. wupcw_omx .mu #mmp .qsou .Nm” Amszpo> xnv o Nmm m NmN .mu “mop .anu m“ 1d 9 Aee=_o> say 8 N05 2 New .Nu peep .ageo ' mm LEE .8 “mm; .38 f 349 D ‘. 1 .N om.N 138 .mm>g:u Ppm mo cowaummcmp:_ Lo ucwoa coseoo ecu gem: mmpasmm cma_t\mg_:__omx mgu Low quQ o_pmg u_o> .m> mmmepm —csco: m>_pomeem N.m teamed NEU\mv_ .mmmLum PMs—Lo: m>wuuwuf+m omm oom emN com omH ooH om o q a u . d _ u _ _ .4 Eu m mgmnw411! N \ x VNF 1w. Amaz—o> aav xnv u Noe . u Ne Amszpo> zav u me L NmN o (/ 32:63. o I ¢>Ib «p ¢>D> // D: 2 L0 a ‘01194 PICA 139 .m—mom E;u_emmop _Emm e co mwFQsmm Lma_e\mu_:__oc¥ mcu so» mm>c=o cram; vwo> .m> mmmeum Pesto: m>wgowmem m.m mczm_u Eo\mx .mmmcum Peace: m>wuumwmu N 08 OS 8 8 2. 8 S H . . _ . . . . q A . . q _ . q _ _ \—\ >1 (4‘71! W“>VH\7 (I V . . 4 . a y, I O o 0. 1H 0 r O eeeee_ee¥ .mu Date .8568 > r 0 $532, 5 u .E n. Nmm .8 or: .558 -N A 0 MI- Aeese, .2: 8 N: a New. .B on: .858 > r m. WW. 253... .8 3...; .38 .m a to > Lm I40 reduced spacing of particles. 2) Removal of water from the inner fiber structure resulting in a reduced cross-section of the total fiber. Assuming that, somehow, one can separate process (l) from process (2), assign to each a different compression coefficient, C1 and C2, such that the cumulative effect yields a curve instead of a straight line as shown in Figure 5.8. The question arises as to which of the two phenomena is responsible for the nonlinear relationship between the normal effective stress and void ratio. Process one is identical to that in dispersed clays (Scott, l963) which yields a straight line relationships between the logarithm of effective stress and void ratio. Therefore, removal of water from the inner‘ fiber structure must be responsible for the nonlinearity. The processes active in the samples may not be limited to only two as explained in the simplified picture. Some of the fibers are folded, others are bent, and some perhaps are in tension, but the dominant variable effecting the shape of the curves appears to be the proportion of fibers. In the case of kaolinite/fiber mixtures the process is perhaps more complex due to bending of clay particles, decreasing distance between clay particles, or a clay particle and a fiber or a combina- tion of both. Regardless of how many or how complex the processes are the overall behavior resembles the behavior of a dispersed or floccu- lated clay depending upon the proportion of constituents in the test samples. There is one difference which will not support the above conclusions for all samples containing fibers. In the case of floccu- lated structures failure is generally of a brittle type yielding a I4l maximum strength. Samples containing fibers in excess of a certain proportion did not show a brittle failure mode. They showed a plas- tic type of behavior similar to that of remolded clay. Samples with 54 percent fiber and 46 percent kaolinite by volume and all fibers showed a plastic behavior. Samples with 25 percent fiber and 75 percent kaolinite by volume show a brittle failure, hence their be- havior is similar to that of flocculated clays. When only a small pressure increment is applied to naturally existing clay, the change in void ratio is small and the approxima- tion can be made that compression takes place as a linear function of pressure. Such an assumption would be far in error if applied to a large change in void ratio such as that occurring between the time of its first deposition and its subsequent burial under deep layers of later sediments. One can therefore assume that the variation of normal stress and void ratio is linear for the range of loads which are commonly encountered in engineering problems. Pressure on a horizontal scale is plotted against the coefficient of volume com- pressibility in Figure 5.9 for the kaolinite/fiber samples. The compressibility in each case is sharply decreasing at low magnitudes of pressure indicating the movement of individual particles closer to one another. At high pressures the compressibility change is practically negligible for all samples, an indication of the close contact of particles. The compressibility of all fiber samples was consistently higher whereas for kaolinite it was consistently lower with kaolinite/fiber samples falling between these two limits (Figure 5.9). These data show that higher organic (fiber) contents 10 9 a, 8 .2 \ N E U “f 7 0 1—1 X Q >< <0 >' 6 >9 H. :3 5 5 U) Q) L Q. E O Q g 4 :3 '8 > 14... O +9 3 C (D 8 q’: q. 8 c: 2 1 0 Figure 5. 142 9 Fiber 54% fiber / 46% kaolinite (by volume) 25% fiber / 75% kaolinite (by volume) Kaolinite _ \ Q‘ 1 1 S - 1 100 200 300 400 Pressure, kg/cm2 Pressure vs. Coefficient of Volume compressibility kao- linite, two kaolinite/fiber mixtures, and fiber samples. I43 increases the coefficient of volume compressibility. Compressibility test sample Cl, all fiber, one square cm 3 at an effective stress of 3.99 kg/cm2 gave a change in volume of l.96 cm? Using the relationship, — [é%-]= CAp,gives the sample compressibility area and initial volume of 4.99 cm = 1.96 4.99 x 3.99 3 = 98 x 10' = 98,000 x lO-6cm2/kg. C From Table 2.3 note that values of CS for clay are close to 2 x l0'6cm2/kg. If it is assumed that C§ varies directly with the specific gravity of the material, then a reasonable value of Cs can be obtained .fon.freeze dried solid fiber material as follows, _ 2.65 -6 _ -6 CS - 1.54 x 2 x l0 - 3.44 x l0 Therefore, C —6 h;?. = 3.44 x l0 -6 = .000035 fiber 98,000 x l0 For comparison consider pure kaolinite. From compressibility test sample 'C4, a sample of one sq. cm. area at an effective stress of'3.99 kg/cm2 gave a volume change equal to .4597 cm3. For an 3 initial volume of 5.684 cm compute = .4597 clay 5.684 x $99 c :=20.27 x 10‘3:=20270 x 10'6 cmz/kg and . 2 E§.] _ 2 x 10'6 c - _6 = .000099 clay 20270 x l0 The numerical value of (23] = .000035 for a pressure of 3.99 kg/cm2 1 “SM .. -g- .. -..- I44 and all fibers is too small to have any significant effect in the equation, - [42% C[Ap - (1 - 2314.1 I (5.2) Cs Therefore the C factor for organic soils can be neglected and it can be concluded that Terzaghi's effective stress concept is valid to a high degree of approximation for kaolinite/fiber mixtures and all fiber samples. 5.2.2 Triaxial Consolidation In the triaxial test a sample was subjected to three dimensional isotropic consolidation before application of the deviator stress. To accelerate the consolidation process side drains were provided in addition to the rigid porous stones at the t0p and at the bottom of the sample. Use of side drains reduced the time required for 95 percent consolida- tion to about one-tenth of the time for only double end drainage (Bishop and Henkel, l962). Since both vertical and radial flow were permitted, separate solutions to vertical and radial flow may be com- bined. In the triaxial specimen the applied stress will initially cause a uniformly distributed excess pore pressure throughout the medium which will begin to dissipate first near the drainage boundary Thus in the early stages of consolidation the material near the periphery of the specimen will have consolidated to a greater degree than the material along the axis of the sample. As ' a result the vertical settlement near the periphery will be larger than the vertiCal settlement near the axis. If the porous stones were flexible, then, due to this nonuniform settlement from the axis of the sample to the periphery, the stones would attain a shape I45 that is concave downward during the consolidation process before be- coming plane again when it was completed.. Since the porous stones used were rigid, the material was strained equally in a vertical direc- tion at all points on the radius near the sample ends and the soil near the surface away from the ends was compressed radially during consolida- tion, a condition that does not correspond to the field situation. The CID test was employed to insure that the soil sample had experienced a specified stress history before shear strength testing and was considered acceptable for the project objectives. Anisotropic consolidation can be used to similate field conditions. Consolidation pressure is plotted against water content at equilibrium for all fiber, kaolinite/fiber mixtures, kaolinite samples in Figure 5.l0. These results are similar to those shown in Figure 5.6 for one dimensional compression except that the horizontal scale has been greatly exaggerated. 5.3 Shear Strength of Kaolinite/Fiber Mixtures The shear strength of kaolinite/fiber mixtures is presented in three sections: direct shear study, triaxial compression, and shear strength parameters 0' and c'. 5.3.l Direct Shear Study Direct shear tests on samples prepared from pulp fibers included: l) Saturated full length fiber samples; 2) Saturated powdered fiber samples; and 3) Oven dry fiber samples. Shear displacement versus shear stress for several saturated 146 160 T 140'- 120 1- v Fibers 100'- R +3 C B S 80 - U 3 54% fiber/46% Kaolinite -g (by volume) 3 V V 601- . V v V j(25% f‘i ber/(75% V/-Kaolinite (by volume) V 40" V7 1:7 <7 ‘7' :7 §; 20., Kaolinite 1 1 1 1‘ 1 L__ .1 0 l 2 3 4 5 6 7 Consolidation Figure 5.10 Consolidation pressure vs. fiber samples. pressure, kg/cm2 % Water content for kaolinite/ I47 fiber test specimens and subjected to varying consolidation pressures are summarized in Figure 5.ll. Note that the shear strength of the specimens continued to increase with increasing strain and no peak shear point values were obtained. The shear strength also increases with increasing consolidation pressure or normal stress for a given shear displacement. For example, sample 36 shows that the shear strength corresponding to a displacement of 0.25 cm is about l.50 kg/cm2 and for a displacement of 0.50 cm the shear strength has in- creased to 2.50 kg/cmZ. Sample 85 loaded with a normal stress of 0.962 kg/cm2 shows a shear strength of about l.l2 kg/cm2 correspond- ing to a shear displacement of 0.50 cm, whereas Sample S3 with a normal stress of 4.06 kg/cm2 shows a strength of about 4.6 kg/cm2 at the same shear displacement. This increase of shear strength with increasing normal stress implies that the shear strength was predominantly due to friction. A linear relationship between shear displacement and shear stress is shown in Figure 5.ll for displace- ments larger than 0.l5 cm which corresponds to a strain of about 6 percent. Shear strength also increased with increasing strain for the same normal stress, indicating a continuous mobilization of the coefficient of friction, tano'. The factor which has the maximum effect on the friction angle ¢' appears to be the density of the material. It is apparent that increased density changes the friction angle 4' which leads to improved shear strength at a constant normal stress with increasing strain. It was observed during the test that the sample appeared to be more dense in the vicinity of the shear plane, as shown in Figure 5.l2. The zone of higher compression is outlined schematically in Figure 5.l3. 148 .mm_a5mm Loewe cmumczpcm nmumnwFOmcoo Lee mm>czo “cosmuepam_u mmmcum cmmcm pumc_o HH.m mgzmpm Eu .gcmsmum_am_c ecmcm m. o. m. w. m. N. u _1 q - fi _ > m; r vm D D m D D D > > > b. HN.N b. .D > mm b ...... . > b > > a > > > .55. 8.5 . 82 858288 mm > N m_asmm N 0") ¢ Zuni/6x ‘ssau1s JESUS 149 (b) Figure 5.12 Direct shear test samples after completion of the tests. 150 I Shear .... plane .C .93 (I) I \\\——-Zone of higher density Figure 5.13 Schematic of the failure zone in a fiber sample after being subjected to a direct shear test. I5I Shear displacement plotted against shear stress and vertical displacement is shown in Figure 5.l4 for Samples S6 and S9. Water absorption during conduct of the test has lowered the strength and increased the vertical displacement for Sample S6 as compared to Sample S9 for the same consolidation pressure and lateral displacement. Shear displacement plotted against shear stress for samples composed of dry powdered fibers are summarized in Figure 5.l5. The shear strength for dry powdered fiber samples also increases with increasing normal stress and increasing shear displacement. The behavior of dry fiber versus saturated fiber samples is shown in Figure 5.l6, where shear displacement has been plotted against shear stress and vertical displacement. The dry fiber samples in Figure 5.l6a consistently show a higher shear strength than the saturated fiber samples for the same magnitude of consolidation pres- sure and shear displacement. The slope of the curves for dry samples are flatter than the slope of the curves for saturated samples indi- cating a smaller rate of change in the density of the material which is further evidenced from the lower vertical displacements shown in Figure 5.l6b. Figure 5.l7 presents normal stress plotted on a horizontal scale against shear stress on a vertical scale for saturated samples corresponding to an assumed failure strain of 20 percent. The result- ing angle of internal friction 0', equals 49.60 degrees with no inter- cept on the vertical axis. Figure 5.l8 shows normal stress plotted against shear stress for dry powdered fiber samples to yield an angle of internal friction ¢', of 47.50 degrees and an intercept on the vertical axis equal to 0.26 kg/cmz. 2 Shear stress, kg/cm Vertical displacement, mm 152 4 r 3 - Consolidation pressure = 2.21 kg/cm2 $9. No water available to sample during dis- 2 placement S6. Water available to sample 1 - during displacement l I I L L J 0 l 2 3 4 5 6 Shear displacement, mm 0 1 2 3 4 5 6 I Ti I I T I 0.4 ' 0.6 L Figure 5.14 Shear displacement vs. Shear stress and Vertical dis- placement curves showing the effect of water absorp- tion during the test by saturated fiber samples. 153 .mmFaEcm emcee cwgmuzoa New cmueuv_omcou Low mm>ezo “cosmoeFQmwu mmmepm Lcmcm Home_a mH.m mezmwm es .ucmsmom_am_c Lemgm m o m, e m N a o q q q H d d _ Nam Mam mH mam .D > N59. m: 1 2.2 8.582628 mam 1 «Pasmm Zuni/6x ‘ssauis JESUS 154 4 r Dry sample 516 1 Consolidation load = 3.45 kg/cm2 . ‘ ‘ 3 _ " Saturated (”3 . sample S7 7‘ 1 3 . 3.4 g? 2 _ ‘ Dry sample 313 3" o g ‘ 1.58 v v m ‘ o T ‘7 Saturated 8 1 o 7 sample S4 .2 _ ‘ 10 ‘v 1 "’ . V 1.58 /v (a) I I I L I I 0 1 2 3 4 5 5 Shear displacement, mm \ r I I I I I E 0 1 "\9. a .0 '— ' I3 " 7T§o A m L \V\ V 0—0—0— 5 0.2 , 8 “‘§$i, . 2 c, a F. 0.3 — 1 J J .95 ' \1 v .0 '— 0‘5” ‘ v v v 4‘5 .53 23 0.5 — V ‘ g (b) 0.6 _ Figure 5.16 Shear displacement vs. Shear stress and Vertical displacement curves for dry and saturated fiber samples showing the effect of water. 155 Displacement rate = 0.0152 cm/min. Shear tests 81 through S7 5 _ Full length saturated fiber samples. Failure assumed at 20% displacement. Shear stress, kg/cm2 II. Normal stress, kg/cm2 Figure 5.17 Summary of direct shear data for fully saturated full-length fiber samples. 156 Shear tests 511 through 518 5.. Displacement rate = 0.0152 cm/min. IZI'= 47.50O Shear stress, kg/cm2 to I N 1 1 4 I l 0 1 2 3 4 5 2 Normal stress, kg/cm Figure 5.18 Summary of direct shear data for dry powdered fiber samples. 157 6— Displacement rate = 0.0152 cm/min. 5_ Shear tests 81 through S7 20% displacement V ‘19"; 49.60 N 41- V s S, V V I- s: 1“ 0 - 37.60 m - 3 v ‘27. ‘ V 5 v v 2% 2" 1 10% displacement ‘V ‘ ‘V 11— V’ L I L L L l 0 1 2 3 5 6 Normal stress, kg/cm2 Figure 5.19 Comparison of direct shear data for fully saturated fiber samples at 10 and 20 percent displacement strain. l58 Figure 5.l9 shows normal stress plotted against shear stress at assumed values of failure strains of 20 percent and ID percent. The test samples show an angle of internal friction 0', of 49.60 degrees corresponding to a strain of 20 percent, and a much smaller angle of internal friction of 37.60 degrees with respect to a strain of l0 percent. There are perhaps two possibilities to explain the significant difference between the frictional angles. The material is either densifying during the conduct of the test with increasing strain or the fiber tension is contributing to the strength of the material which appears in the form of improved frictional angle. 5.3.2 Triaxial Compression A discussion of organic versus inorganic soils illustrates the differences in response of the two soils under triaxial compression. This is followed by a discussion of consolidated undrained tests and consolidated drained tests. 5.3.2.l Organic Versus Inorganic Soils Consider the cross-section of an idealized organic soil, i.e., cross-section of fibers and an inorganic soil as shown in Figure 5.20. In inorganic soils, for example sand, the solid grains are very stiff and the imposed load is carried by the solid particles struc- ture under drained conditions. The external load is transmitted through the contact points of the solid grains. For all practical purposes the deformation of the solid particle is very small and can be neglected. The change in void ratio during application of a load occurs due to small movements of the particles, i.e., the parti- cles move closer together resulting in the reduction of the volume 159 Incompressible particles Pore water water inside and between the fibers Cellulose fiber in the swollen form Figure 5.20 (a) Saturated inorganic soil fabric (b) Idealized saturated organic soil. I60 of voids. The change in void ratio is due entirely to the change in the volume of the space existing between the solid particles. The same reasoning can also be applied to compressible inorganic soils such as clay. In organic soils the phenomenon includes the hydrophyllic nature of the fibers. The total amount of water in a saturated organic soil sample is the sum of the amount retained between the individual (solid) fibers and the amount stored within the porous structure of the fibers. When this sample is subjected to an external load under drained conditions the water from between the fibers and from within the structure of the fibers is squeezed out giving rise to a large change in void ratio and a reduction in the initial swollen volume of the fibers resulting in a smaller cross-section. Hence the total change in the void ratio is due to the cumulative effect of a reduc- tion in internal pore volume and a closer packing of the individual particles. This would mean that at higher consolidation pressures the amount of water contained within the fiber structure will be reduced resulting in smaller cross-sectional areas. It is this hydro- phyllic nature and structure of the fibers that is responsible for the high compressibility of organic soils. A dry fiber structure should not be nearly as compressible as the saturated fiber structure as has been observed in the direct shear tests. Consider a saturated sample composed of a fiber-clay mixture. At low consolidation pressures and at equilibrium, water retained by the fibers will maintain flexible swollen structure and larger distances between fiber particles. Fiber and clay particles will be separated by l6l several layers of water molecules. Due to the hydrophyllic nature of the fibers the water distribution within the sample will be nonuniform, larger masses of water being held by the organic fibers. At higher consolidation pressures clay and fiber particles will be forced closer together. The expulsion of water results in a denser fiber-clay struc- ture. If the fiber quantity is controlled with respect to the clay, a matrix of these materials may behave like a reinforced material at low water contents. It would appear that the strength of the fiber-clay sample depends upon the ratio of the two materials present and the magnitude of the applied consolidation pressure. 5.3.2.2 Consolidated Undrained Tests Both brittle and plastic failure (Whitman, I960) can be observed in inorganic cohesive soils. Brittle failure is characterized by the development of a peak stress and the formation of failure planes. Plastic failure involves a continuous increase in deviator stress past 20 percent axial strain and sample bulging. The pure clay samples and the samples with 25 percent fiber/75 percent clay exhibited peak strength, (5.l - 53)max' Failure in soils is usually a progressive type of process and the (51 - 53) value corresponds approximately to the point at max which structural collapse of relatively stiff material takes place. Soils lacking structural stiffness or rigidity show a more viscous type behavior. For such soils it becomes difficult to define the stage in the shear process which represents failure. Consolidated undrained triaxial tests with pore pressure measure- ments were performed on kaolinite, kaolinite/fiber mixtures, and fiber samples. The results from nine undrained triaxial tests on kaolinite l62 5+5 on a hori- samples is summarized in Figure 5:2lz The values of~—l——¥i o o 2 zontal scale are plotted against 12 3 on a vertical scale resulting in a kf-line inclined at an angle a of l9°, hence a ¢' of 20.l4°. All samples exhibited a brittle type failure with a well-defined failure plane. The data points corresponding to consolidation pressures higher than 2.5 kg/cm2 align well on the kf-line (Figure 5.21) indicating reasonably good agreement. The first two points corresponding to lower consolidation pressure fell above the kf-line. This deviation indicates some overconsolidation related to the method of sample pre- paration. The result of four consolidated undrained triaxial tests on samples with 25 percent fiber/75 percent kaolinite, by volume, are sum- marized in Figure 5.22. All 9amples exhibited abrittle failure with no clearly developed failure plane. The failure strains for three of the samples varied from 8.45 percent to 8.8l percent, whereas the fourth sample failed at about l5 percent. For consolidation pressures 2 good agreement between data points was observed. of 2kg/cm2 to 6 kg/cm The kf-line in Figure 5.22 gives an angle a of 23° with an intercept of 0.26 kg/sz on the vertical axis. The shear strength parameters 0' and c' are therefore 25.l2° and 0.29 kg/cmz. The vertical intercept may be caused by development of tension in fibers extending across the failure plane. As the fiber content in the fiber kaolinite mixtures was increased a decrease in stiffness with a more plastic behavior was observed. In such cases an arbitrary 20 percent axial strain was defined as failure. This criterion has been extensively used as a definition of failure, 163 .muHcHHoex to» eueu “may HechHLH cmchcccz uchuHHomzoo mo acmeszm HN.m mezmHm mo+Hb m m e m N H o H H H m H H v 0G,"? J, 54H.oN 1.5 11 5:6“. 111. HGCPW IH ID. 2 H 0. (cc 52 1. e ...... IN w xmsHmo1Hcv Hm mezHHmu w7o mHHcHHocx co mummp HmewHeH cmchcccs umHmUHHomcou 164 .HmszHo>-an mmHaEem.mpHcHHoe¥ Nmm\emnHH NmN cow tutu HmemHeH umchcucs umpeuHHOmcoo Ho Aeneasm NN.m mezmHm me Ame-Hev em et:_eed Aee=_e> Nev weeewpeex Hme\mcee_e Nmm L0H mummy HmechH vmchcucs umHmUHHOmcou I65 especially in the case of inorganic soils like clays. This failure criterion appears to have shortcomings, some obvious and some not so obvious, particularly in the case of soils with high organic and water contents. An alternate technique for defining strength at failure is suggested for organic soils in the following paragraphs. Data from three consolidated undrained triaxial tests on samples with 54 percent fiber/46 percent kaolinite by volume are shown in Figure 5.23. The test samples did not exhibit brittle failure, there- fore the Mohr envelope shown was based on an arbitrarily assumed axial failure strain of 20 percent. Consolidation pressures ranged from 3 kg/cm2 to 6_kg/cm2. The kf-line passes through the origin with an inclination a of 33°, hence a shear strength parameter 0' of 40.49°. The strength envelope does not show any intercept on the vertical axis indicating a lack of any’cohesion. Using a p-a plot for the determination of the shear strength parameter 0', is a standard procedure in geotechnical engineering, however, in certain cases as will be seen later in this section, it can lead to unrealistic conclusions if the limitations on the method are overlooked. The limitation of the method becomes obvious when applied to compressible organic soils.in which excess pore pressures reach values equal to the cell pressure, i.e., the effective minor principal stress goes to zero. The B-g plot shown in Figure 5.24 was based on the results of triaxial tests performed on pure fiber samples subjected to consolidated undrained conditions with pore pressure measurements. Pulp fibers are hyrophyllic in nature giving rise to high water contents. All fiber 166 .mmcszHs AwasHo> any HmHo Nm¢\gmnHH New toe 8.8 3.58.75 H5522: 63.83328 46 .2253 NH“ 853... so a . 11MM11 N \ x Hme+Hev e m e m N H o H q H H H H «17 LH 9Qc( ome.oe 1.” ace“ 1. :Hm 179. J N 2T... 0. (CG 1 m _mw 3 w 2 5mm 1 e L 3 :ngpm NoN Hm amazmmm mngch Aee=_e> say eeee__ee¥ Nee\meenee Nem co mummy HemeHLH vwchLucz anmvHHOmcou L 167 Consoiidated undrained triaxiai tests on fiber sampies Faiiure assumed at 20% axial strain Figure 5.24 Summary of consolidated undrained triaxial data for a1] fiber sampies. 168 samples, when subjected to triaxial shear, exhibited plastic failure. In such cases failure is usually based on an arbitrarily assumed axial strain. The value often selected varies from 10 to 20 percent depending upon the project type under consideration. One phenomenon, perhaps a unique characteristic of organic soils, is the tendency of the pore pressure to become equal to the minor principal stress 03 (cell pressure) at strains anywhere between l5—20 percent. In some extreme cases, which have been observed (Hanrahan, 1954; Andersland and Charlie,1975) during triaxial tests, the effective minor principal stressB3 becomes equal to zero resulting in a E-a plot with kf-line inclined at an angle a close to 45°, hence a shear strength parameter ¢' close to 90°. As long as the pore pressure becomes equal to the cell pressure a ¢' value of 90° will be consistently obtained from a p-q plot regardless of the material tested. In Figure 5.24 (51 + 53)/2 on a horizontal scale is plotted against (<31 - 53)/2 on a vertical scale for 100 percent fiber samples subjected to consolidated undrained triaxial tests, where 5] and 53 values are based on an assumed failure strain of 20 percent. Excess pore pressures were equal to the cell pressure at 20 percent strain for samples normally consolidated to low pressures. In the case of samples normally consolidated to relatively higher pressures, 53 values were not zero but their magnitudes were small compared to 5] values at 20 percent strain. The average kf-line shown is inclined at an angle a of 44.60°, hence a shear strength _parameter ¢' of 80.44°. Note that the pore pressure indirectly con- trols the inclination of the kf-line. This observation is obscure for inorganic soils since brittle failure takes place long before the 169 pore pressure has a chance to rise and become equal to the cell pressure. An alternate method is suggested, the application of which is limited to those normally consolidated materials demonstrating plastic failure. Two assumptions are made, namely that the cohesion is zero for normally consolidated samples and that the failure is defined at a maximum 6i. ratio where T is the shear stress and 06 is the effective normal stress at any strain value during the test process. A stress path or the locus of (57') is plotted and the peak point on the max n curve is assumed to be the shear strength. A straight line passing through the origin and the peak point is assumed to represent the strength envelope inclined at an angle equal to tan-1(gT)max. Experi- n mental data for an all fiber sample and a sample with 54 percent fiber/ 46 percent kaolinite by volume is shown in Figure 5.25a and 5.25b using this criteria. Note that the shear strength corresponding to a tan'1(—$-) of 90° is zero. For samples with pure fibers tan-1(§&J on n equals 39° and for samples with 54 percent fiber/46 percent kaolinte by volume, tan-1(gTj equals 34.8°. For pure kaolinite and samples with 25 percent figer/75 percent kaolinite by volume this criteria was not used since a brittle failure, i.e., (61 - 63)max was observed. This approach appears to define a useful strength criteria for those materials in which the pore pressure tends to approach the confining pressure. This definition is limited to normally consolidated materials. At this stage of the development, overconsolidated fibrous organic soils have not been investigated. Mohrs failure envelope was assumed to be a straight line in Figure 5.22, 5.23 and 5.24. In reality this envelope may not be a straight line depending to a significant extent upon the magnitude of 170 3 H -1 T _ o l— - A tan (671')max—39 (a) CU-Fl All fiber Consolidation pressure 2- 2.5 kg/cm2 CU-F4 All fiber Consolidation pressure 3.5 kg/cm2 CUTFI . 0 1 2 3 4 5 5, kg/cm2 -1 T = 0 tan (aflmax 34.8 CU-CFl (54% F/46% c by volume) . Consolidation pressure F ----------- 3.0 kg/cm2 Shear strength 1.3 kg/cmz r, kg/cm2 Figure 5.25 Stress paths for samples with (a) all fibers and (b) 54% fibers/46% Kaolinite (by volume). 171 the applied loads. The loads in turn cause a change in porosity giving rise to a curvilinear failure envelope. A brief discussion related to the geometry of the failure envelope for soils follows. If a change in porosity causes the failure envelope to change its shape from approximately a straight line to a curved line, (Section 2.5.3) then one should expect a curved failure envelope for normally consolidated clays since with increasing consolidation pressures the porosity will decrease. But normally the failure envelope for normally consolidated clays is approximated by a straight line for the stress levels encountered in most geotechnical problems. The porosity change causing a nonlinear failure envelope is associated with the increase in contact area of the solids and this change in contact area can only occur if there is l) yielding of the solid material at the points of contact or 2) the increase in the number of contact areas. In normally consolidated clays the contact area does not change significantly. Con- sider Figure 5.26a where the clay particles are shown a certain dis- tance apart by layers of water with respect to a certain consolidation pressure. When the consolidation pressure is increased clay particles are forced to move closer, (Figure 5.26b) but the contact area between the solids remains practically unchanged, and consequently the Mohr envelope will exhibit a straight line geometry. Consider now Figure 5.26c where an idealized diagram of two adjacent saturated fibers is shown. At a low deviator stress and therefore at low strains the near saturated fibers maintain approxi- mately a cylindrical cross-section and the contact area between the solids is relatively small. As the deviator stress increases, strain will increase with more and more of water being expelled from the 172 ' {Ah C] ay VIIIIIII!‘ f V C] 6y V ‘ . ‘ ' l 'Illlllllll LAh (a) (b) Figure 5-25 (a) Clay plates at low consolidation pressure (b) Clay plates at relatively higher consolidation pressure (c) Cross section of fibers at low strain and (d) at higher strain. 173 fibers resulting in a change of geometry as shown in Figure 5.26d. This change in geometry will result in an increase in contact area and therefore a change in the porosity as well.. Assuming the above explan- ation is reasonable, the failure envelope for samples having a composi- tion of all fibers or fiber-kaolinite mixtures subjected to a drained triaxial test, will probably in the strictest sense be curvilinear, where the curvature of the envelope would be a function of the propor- tion of fibers in the sample and the consolidation pressures. Pressures used in these triaxial tests were comparatively small, hence no curva- ture is observed and the straight line with an intercept on the vertical axis gives an acceptable approximation of the failure envelope. 5.3.2.3 Consolidated Drained Tests For inorganic soils experimental work (Bishop and Henkel, l962) has shown that the strength parameters ¢' and c' are almost identical for consolidated undrained and drained triaxial tests. Test data presented in Section 4 show that this is not the case for a model organic soil. The previous section outlined the problems involved in identification of the stage in the shear process at which a soil is said to be failed for undrained tests. Questions arose when the pore pressure increase reached values equal to the confining pressure. This problem was avoided for drained tests in that drainage is permitted and excess pore pressures are permitted to dissipate. Measured total stresses are therefore equal to effective stresses. Triaxial test results on samples made of 25 percent fiber/75 percent clay by volume subjected to consolidated drained conditions are shown in Figure 5.27 with(51 + 53)/2 plotted on a horizontal axis 174 .mmgauxHE AmazHo> xnv muH=HHom¥ xmfi\cmnHw Hmm Low mean Hmemng vmcwwgc umpmnHHomcoo Ho mgweszm Hm.m mczmHu :ngum Hmem &om pm umszmmm wngHmu 3539, § 3.223. $128: fim co.mummu HmemHLu nmcwmeu cmpmuHHomcou 175 against (51 - 53)/2 on a vertical axis. The data approximate a ”A kf-line inclined at an angle a of 2l.80°, hence a ¢' of 23.58°. The kf-line also gives a cohesion c' of 0.45 kg/cm2 on the vertical axis. This intercept may be the result of fibers extending across the shear plane going into tension. Triaxial test results on samples made of 54 percent fiber/46 percent kaolinite by volume subjected to consolidated drained condi- tions are shown in Figure 5.28 with (51 + 53)/2 plotted on a horizontal axis against (51 - 53)/2 on a vertical axis. The kf-line is inclined at an angle a of 22.50°, hence a ¢' of 24.74°. The cohesion c' given by the kf-line on the verticalaxis equals 0.53 kg/cmz. The shear strength parameter ¢' of 24.47° for this case is larger than the ¢' of 23.58° given by samples with 25 percent fiber/75 percent clay by volume, showing perhaps the additional friction contribution by the fiber in the sample. A plot of kf-line for fiber samples subjected to triaxial drained tests is shown in Figure 5.29 with (51 + 53)/2 plotted on a horizontal axis against-(51 - 53)/2 on a vertical axis. The kf-line is inclined at an angle a of 27.25° making ¢' equal to 3l°, an angle larger than those obtained for mixtures containing kaolinite. This behavior shows a frictional contribution of the fibers. The data points plotted in Figures 5.27, 5.28 and 5.29 are all based on an assumed 20 percent axial strain since in the case of drained tests essentially all samples showed a plastic type failure. A comparison of the stress-strain curves for samples made of kaolinite, 25 percent fiber/75 percent kaolinite by volume, 54 percent fiber/46 percent kaolinite by volume, and all fiber is shown in 176 .mmgzuxps AmazHo> anv muH:_Hom¥ x©¢\gman Rem Low mpwv HmemHLp umchLu cmpmnHHOmcoo mo Accessm mm.m mezmwu EU m a (Will N \ x Amb+fiov NH 2 N o N N o H H q H H H Ile¢o N EU\mx mm.o urwmmw u u N .w . N )0. aisle 2m. .23 - 95m 4m (9 ..v m. o 3 com NN u .5 -m we .6 :ngpm Hmem New um amazmmm mezHHmu LN st=Ho> any m»H=HHON¥ No¢\emnwm New co mummp HmemHLp vm:_mgu umumcHHOmcou 177 .mmHaEmm LmnHw HHm Low cums HmeNHLp cwchLu wwawuHHomcou so acmeszm mm.m mczmHu so a . N N N x Amb+fiov NH 0H m o v N o q H H H H q -H )0. nN 2T... 0. (CG OHM ".9 LM 6 .acmu ".92Hm mm ..Q m z omN.NN 2.0 -m 1o :_E\Eu NHmoo. mum; :ngpm.usw. :Hs\ao mNoo. meme :ngpm.ubw. :Hmepm New um cmszmmm mczHHmm ma-ao gazocsb Nd-ou moHaEmm LmaHH co mama“ Hwamng cmchLn emumcHHomcou 178 .mcoHHanoo um:_mgucz Low mEmH=mcows mesHHmH :H «usage as» m:_zo;m mcoHHHmoqsoo gmaHm\mHH:_Homx m:_>gw> 5HH3 mmHQEmm com mw>g=o chgumnmmmgum & .chgum Hme< om.m mesmwu mH oH «H NH oH w H - H H H H H NEU\mx m.m u mczmmmca :oHHNnHHomcoo 32:23. > > . > > > >> EU\mx m u wezmmmga :omumnHHomcou .mngHmH mHHHHLm mHH=HHow¥ xmm LmaHH xmm H H H H H H . so}! m 83.39,. 0H Him 9‘ umczmmmea compovzomzoo 00 o o O 00 ‘ mHHcHHomx New emaHH Nvm r y NEU\mx m u mezmmmga :owumuHHOmcou r r Lwn: I! ) 8o-Io w 6 ‘ z 3/ x ( 179 Figure 5.30. The curves demonstrate the change in the failure mechanism as the proportion of the constituents in the sample is altered. Kaoli- nite samples and samples with 25 percent fiber/75 percent kaolinite by volume exhibited peak strength values marked by an arrow on the figure. Samples with 54 percent fiber/46 percent kaolinite by volume showed a behavior similar to that of dispersed clay where shear strength gradu- ally rises with increasing strain. Samples with all fibers exhibitéd a behavior typical of remolded clays. 5.3.3 Shear Strength Parameters ¢' and c' When effective normal stresses and shear stresses acting on the failure plane at failure are plotted on a horizontal and vertical axis, respectively, the resulting line is defined as the Mohr failure envelope. Theinclination of this line and the intercept of the shear strength envelope are defined here as the shear strength parameters ¢' and c', respectively. 'A summary of triaxial data for consolidated undrained tests on samples with 54 percent fiber/46 percent kaolinite by volume, is shown in Figure 5.3l in terms of the maximum ratio of shear stress to effec- tive normal stress. The plot includes results from tests CU-CFl through CU-CF3 and the data reported by Charlie (l975) for papermill sludge samples with about the same organic content. Samples prepared from the fiber kaolinite mixture and the papermill sludge both show good agree- ment. Each point on the straight line inclined at an angle ¢' of 35° is based on the peak point of the stress path as shown for samples U-l-l3 and CU—CF3. A summary of the shear strength parameters o', for all the 180 .mmmgwm Hasgoc o>HHomwmm cu mmmgpm gmwgm Ezewxms 05H co cmmmn mngHmw .mszHo> an zmHu woe >8an Ham 5.; 8323 :o 8.me 8522: 323328 LE 3% 2.3.587: Hm.m 853“. mso\mx .m N o m e N N H q d chmgpm ,/ H a . w/ _ u. pmwxw fiv mm. // MPIPID HH // H x . H , N /, mHnEmm H I, N x H / N x . .2 x \ TON 2. . / SH N x, . 4 , SN . . :H x/ \\ le.\\ m¢.m / No.N / x o / \\ // \\ I. I \ meu-=u ,, N. mHnsmm ,, x N: . x \ .NH . 3.2 Nm\\ mg L 0mm u _H NH-H-: emzoegp OH-H-: 3m: .32 32.35 so: 38 1D: $0-8 19.85 5.3 3.0.3 :0: 181 4‘ ....._'_. _____________ _A fi 100.:7 Brittle behavior " ”' Plastic behavior Cfifi'Test (after Charlie 1975) 80 - V a; O a) — 'U CIU Tests -“ (after Charlie 1975) .9. a 60 - _ 'é IU Tests g ETU Tests CIU test, failure a. (after Laza 1971) at peak value of '5 O V / stress path. as _ 55 40 __fi7r i: v "’ V 2.: ., . .32: /v V Consolidated - 20 Drained tests, failure @ 20% strain 0 20 40 60 80 - 100 % fiber by volume 6 . 2E) ' 40 Y 60 - ab 1 160 % fiber by weight Figure 5.32 Fiber (organic) content vs. shear strength parameter ¢', consolidated undrained and consolidated drained tri- axial tests. 182 samples subjected to consolidated undrained and drained triaxial tests is shown in Figure 5.32. Kaolinite samples and samples made of 25 percent fibers/75 percent kaolinite exhibited typical brittle failure. All fiber samples and samples made of 54 percent fiber/46 percent kaolinite showed a departure frOm brittle failure. In these cases an arbitrarily assumed value of 20 percent axial strain was used as the failure criteria giving upper and lower curves shown in Figure 5.32. For the intermediate case the shear strength parameter ¢' was determined on the basis of (5)!“ax stress paths for undrained triaxial tests. Peak values on the stress paths were defined as failure since they represent the maximum shear strength as shown in Figure 5.25. Note that this method was used only for fiber samples and samples with 54 percent fiber/ 46 percent kaolinite by volume, since they did not show brittle failure. The values for the shear strength parameter ¢', for organic soils depend upon the test method used. Note that the disagreement between ¢' values, based on different test methods used, increases with in- creasing organic content.‘ A summary of shear strength parameters deter- mined from different test methods and based on different failure criteria are given in Table 5.l. 5.4 Implications for Stability Problems This section reviews the compressibility and stability of organic soil deposits in terms of experimental results for the model kaolinite/fiber soil. The material is presented under two headings: settlement and stability. 183 Hmmu HONxOHNH umcHOLc NHHOUHOOLHONH umamuNHomcou u QH x NOHQ u o mHman mmmxpm m>NNQmNNm .pmmg HmeOHLH umcHOLuzz NHHNQNOOLNONN cmNOvNHomcou 0 Leave gpmcmH Hsz n me u =Hu+ O _N ONONNN HaNNN NON ONO HOOOONO HHONO NOONN HNON_az NOV ONOONNNON N0.0 N.ON OHNNON HNNNO NON ONO NasOHO> NOV ONOONNNON < ANONNaz NOV ONNNNNNON O0.0 O.NN ONNNNN HONNO NON ONO HasOHO> NOV ONONNNNNN o mm xma samalmmmepm ll. . Hm\ev mzHO> Nam; O O.ON O_acpm HNNNN NON N ONO NONOONH HHONO LOONN o mm xms sung mmmgpm HmNNO .aOHa> Naaa HNOONaz NOV ONOONNNOO O 0.0N OHOLNN HONNO NON .DNM HNEOHO> NOV ONONNNNON XE ON.O H.mN O NOm-HmO NOOOHmz NOV ONONNNNOH NNOOOLNN NONO .mwm HmsOHO> NOV ONNNNNNNNN O H.ON NOENNm-HmO gumcmgum xmmm +.wa mHNONHomx . Hmmp ON.O N.NN NOQENONHOWNO NON eaagm Noae_O NONLOOOONV NOON; l pmmh . O O.OO NONENQNNONNO NON . eaaem NOQN_O HONOOOO HHONO caOHN Hm mcmumscgma EQ\mxv.o . H.mmuv.e camcmgum gwmcm NNLaN_eO mezHHmm cmszmm< “mop mo maxh cowpwmoaeou mHOEmm mmmpmzm’7----;:...--.;..: ~.".- 3-I‘.'~ ' 1 ft 1‘1... 14'} .... l' .: ',-.'- --.",."‘. SAND _ 100 f. I 2 . yam. - _pc . . / LOWER SLUDGE LAYER Figure 5.33 Cross section of the 1:8 slope, before and after failure, with slice locations shown for the stability analysis (after Charlie, l975). 187 consolidated sludge layers with sand drainage blankets at the bottom, middle, and top. A three foot earth surcharge, used as a consolida- tion load, served to help produce the planned slope failure. Instru— mentation (Charlie, l975) behind the excavated slope included pneu- matic type piezometers, slope indicator casings,and settlement plates. Data from the piezometers are shown in Figure 5.34 including the distance behind the toe of the slope failure. Data at the slope failure surface was not available. Use of ¢' in a stability analysis requires effective stresses and that pore pressures be extrapolated to the failure surface. Water retention characteristics for the fibrous papermill sludge (Laza, l97l) indicates that pore pressures at the excavation surface would be in tension, i.e. water would be absorbed. This fact was used in estimating the pore pressure variations shown in Figure 5.34. Organic contents of the embankment sludge varied with production changes at the papermill. Using ash content data reported by Charlie (1975), average value of 43 percent for the upper layer, gives an organic content close to 57 percent by weight. For this organic content Figure 5.32 gives three possible ¢' values for the kaolinite/ fiber mixtures. The higher value of 52 degrees appears to more closely represent field conditions in recomputation of the factor of safety of the excavated experimental slope (Charlie, 1975). The composite failure surface shown in Figure 5.33 has been analyzed using Janbu's (1954, 1957) method (Table 5.2) with the same slices selected by Charlie (l975). Values for tanu, Ax, and p remain the same with a new value for ¢' equal to 52 degrees used 188 Excavated 0 // #8 0 7 r, W I V1 7| /’ 1 20 30 4O / / fiéistance from toe of failure wedge, ft. // -1-I// Excess pore pressure Au, psi Instr. Group #4 Instr Group #6 Instr. Group #5 Figure 5.34 Estimated pore pressures near the exposed sludge surface based on field (Charlie, 1975) and laboratory (Laza, 1971) data. 189 for the fiberous papermill sludge. Extrapolated pore pressures (Figure 5.34) appear to be negative in slices 2, 3, and 4. The computed factor of safety is close to unity suggesting that ¢' fromthe consolidated undrained triaxial test is best suited for fibrous organic soils. Lower values of ¢' will give a much lower factor of safety thus eliminating the drained test and the CIU test with failure based on the peak value of the stress path from consid- eration. Values of ¢' from Laza (1971) and Charlie (l975), shown in Figure 5.32, require excess pore pressures greater than measured values in order to give a factor of safety equal to unity. In either case, the consolidated-undrained triaxial test gives ¢' values in best agreement with field behavior of the excavated slope. Some doubt still exists regarding the selection of ¢' when the failure slope of 58.6 degrees is taken into consideration. If the active Rankine state (Terzaghi, 1943) exists in the slope at the time of failure, the slope angle a (Figure 5.33) should equal (45 + l/Zo'). Measured lateral movements (Charlie, l975) close to two inches greater at the top of the upper sludge layer as compared to the bottom would satisfy the usual requirements for the active Rankine state. Compu- tation of ¢' in this manner gives a ¢' value close to 27 degrees, the same value observed for the drained test at an organic content of 52 percent by weight. It is apparent that more field data are required before this anomaly can be fully explained. 190 .mchoq N\H Loon mg“ cmzogzu NON—m comm :o mmogow mc_m Low “macs“ No mcHH O Low H a New. ”.mmw u NN w>Nm mcoNpOHonOo HmcoNpan< Hm mm msmm mzu cwaame o ucm m .H mmuNHm Low .9 new mmoHHm HHN NON a ucm .x< .8cmp .NcmN63 an NNm a Ncwgcoo uHcamLo mmmgm>m :O LON mm.m mLOmHN Eoew :oNNuNNN Hmcgmch No mHmc4HH4Hm omh<42mHz m.< mom >5 .oOoH Nso\ox ¢.N so» mucmemwme oLmNN .1mm u + NN.HN oomm.o oon.o NNoN.m NNoN.m oHoN.oom NN.HN Noom.o omem.o NomN.m Nomm.m oNoH.mHm Nm.oN oome.o voom.o HoNN.m NoNN.m oovo.ooN oN.¢m oom¢.o Nmo¢.o omou.m omoH.m Nmoo.oHN oH.m¢ mon.o Noo¢.o NNNo.m «Neo.m mNno.HNH No.om NNHo.o mmvm.o omom.m omom.m NooH.mNH Hm.oN Nooo.o ooHo.o mNo¢.m mNo¢.m NHmN.Hm No.oHH oooo.o moon.o oNNm.m oNem.m mooH.mm N¢.omH ono.o Nmno.o NNNN.m «mmN.m Hooo.m¢ oo.oNN oHeN.H Homo.H ONHo.m «NHo.m on¢.NN co.Nm¢ Noom.H Noom.H oNNH.N oNNN.N on¢.¢H oo.oom mom¢.N mmmH.N ommm.H ommo.H «Nom.o --- ommo.¢ HooH.¢ Noooo.o «oooo.o oNo¢.N ox\m5u -oH x H>EV HmEuv H Euv H.Euv HHH.aHmmm Q58 8 >> muHo> >< waaHo> :4 .Hono: H 56\oxv .HOH HO HOOHOHHNOOO OHNON OHO> NO eeOHO> OH OOOOOO OH OOOOOO NOOOH NEONNOO.O u eeOHO> HOHOHOH NNH.NO 1 3:68:66 eeHez HOOHN EuHmoo. u moHHom Ho mEOHo> NEUP mmLm cowuommlx mammHu NooH .Ho m4o2> moHo> >< s=Ho> :4 .Honm: H Nsu\o¥v .Ho> Ho HcmHuHHHmoo oHHON oHo> Ho mEOHo> :H mocmco :H wocmzo NoOoH 11m mEOHo> HOHHHcH mcHHom Ho mEOHo> Omen HmcoHHommrx NEU\ox No¢.N Hcmpcou Loam; HmcHN mgzmmmgo :oHHmoHHomcoo mono> >m >eH HNEUV Hweeo H.e6o HHH. nHmmmHneoo 6 >> moHo> >< EOHo> z< .Honm: H EQ\oxv .Ho> Ho HcmHuHHHmoo oHHOm oHo> Ho mEOHo> =H mocmso cH mocmzo NoOoH mEoooom.¢ u maaHo> HOHHHOH NH¢.oN u HOchoo Noun; HOOHH mHmo.H u moHHom Ho waaHo> Nae H u Omen HOOoHHuwm-x NEO\ox No¢.N u meammmga :oHHOoHHmcoo mono> >m >eH HOEOH HMEOV H.e6o HHH. aHmmmeasoo a >> moHo> >4 EOHO> 2< .Hnon: H NEU\oxv .Ho> Ho HOoHoHHHmoo oHHOm oHo> Ho mEOHo> :H moOOzo OH mocOco NOOOH HOHo NooH mac oeoo.m u msOHo> HOHHHOH Noo.oH HOOHOOO HmHOz HOOHN mac Noom.N NEoH > OmeO HOcoHHumm-x NEU\ox No¢.N u mgzmmmeo :oHHOuHHomcoo 212 oo.omm «HoH.H NNoo.o meme-oH ONHo.m oHo.oH oo.Hm¢ Ooom.H Hoom.H moeo.oH mooo.N HNo.¢H NN.Hmo «Nmm.H Homo.o mon.HH «Noo.N oHo.o oo.Hmo oOHH.H oooo.o ommm.oH ONmm.N om¢.H OH.HmNH momo.N mon.HH Hon.OH OomN.N Hoo.o mm.mo¢H oeHm.N NNNN.¢H oeHo.HH mHmo.H omN.m oo.NmHH HmoN.N NHmo.mH omo¢.oH oNHo.H mHH.m mH.¢HNN mmmo.m mooN.HH HHoN.o oomm.H mow-N om.N¢oN oomo.m HmoH.oN oNON.m oNHo.o moo.H --- omoo.¢ ono.oN oooo.o- oooo.o oON.H Oimea H-OH x HOeeo H 8H :3 HHH. aHmmmHaeoo a >> moHo>_ >< waaHo> g< .Hgon: H N56\oxv .Ho> Ho HcmHoHHHmoo oHHON oHo> Ho msoHo> OH mocOzo :H oocOzo NoOOH mso oNoo.Hm n mEOHo> HOHHHcH Nmm.mo u Hempcou HwHOz HOcHN mac ommo.m u moHHON Ho wEOHo> Nso on¢.o - NOH H n OmHO HOcoHHomm-x NEQ\ox ON.H u mesmmmea :oHHOoHHomcoo mammHN HooH..mu mHaz> mcHo> >< mazHo> g< .Hnon: H EO\oxv .Ho> Ho HcmHoHHHmoo oHHOm cHo> Ho OEOHo> H_H mocOgo H_H mocOzo NoOOH Eu mHNo.oH n mazHo> HOHHHcH NHm. Hon Hcchoo HmHOz HOOHN we omHo.m u muHHom Ho wEOHo> Nae onO.o 1 NOH H u OmHO HOcoHHowm-x NEO\o¥ No.o.u «Hammmeo coHHOoHHomcoo mammHu NooH .oo mHoz> moHo> >< E=Ho> s< .Hson: H EU\oxv .Ho> Ho HcmHoHHHmoo oHHOm oHo> Ho «EOHo> :H mocOco :H mocOco NoOOH NmH.om Hcchoo HmHOz HOOHN eO OHOO.ON w OeOHO> HOHHHOH «we HON0.0 OOHHOO HO OEOHOH Eu onem on NcH H OOHO HOcoHHumm-x. mammHm NooH .Hu mgoz 17.941 .075 .1905 +.004 .0102 5.9677 3.0064 71,05 32.295 .083 .2103 +.005 .0127 5.9162 5.4587 85.33 38.786 .090 .2235 +.006 .0152 5.8709 6.6065 93.98 42.718 .100 .2540 +.007 .0178 5.8064 7.3571 97.74 44.427 .120 .3048 +.011 .0279 5.6774 7.8252 Sudden rupture occurred and the lateral load decreased abruptly. *After consolidation. 228 TABLE C.11 DIRECT SHEAR TEST DATA, SAMPLE S11 Material: Dry full length fibers Normal stress = 2.20 kg/cm Dry density*'= not available Water content*=---% Consolidation Pr = 2.20 kg/cm2 Load Load Lateral Vertical Are? Shear (lbs) (kg) Displacement Displacement (cm ) Stress * (kg/cmz) (in) (cm) (in) (cm) 4.51 2.045 .003 .0075 -.002 '-0051 6 4323 ~3179 7.14 3.245 .007 .0178 -.003 ‘~0075 6 4064 ~5055 9.77 4.441 .011 .0279 -.004 “~0102 6 3807 -6960 12.59 5.723 .015 .0405 -.005 '-0127 6 3485 -9015 15.41 7.005 .022 .0559 -.005 ‘-0152 6.3096 1-1102 18.23' 8.286 .029 .0737 -.007 ‘-0178 6 2644 1.3227 20.58 9.400 .038 .0955 -.008 “~0203 6 2065 l 5145 23.12 10.509 .052 .1321 -.009 '50229 6 1161 1.7183 24.25 11.023 .055 .1551 -.010 ‘-0254 6 0322 l 8274 25.55 11.518 .085 .2159 4.010 ‘-0254 5 9032 l 9581 27.25 12.391 .112 .2845 -.011 "0279 5 7289 2.1629 28.19 12.814 .125 .3175 -.011 '-0279 5 6452 2~2699 29.14 13.245 .145 .3583 -.011 ‘-0279 5.5161 2.4012 30.45 13.841 .155 .4191 -.012 “ 0305 5 3871 2 5693 31.39 14.268 .180 .4572 -.012 '-0305 5 2903 2 6970 32.52 14.782 .200 .5080 -.o12 '-0305 5 1613 2 8540 34.59 15.723 .220 .5588 -.011 “-0279 5 0322 3 1245 35.09 15.405 .250 .5350 -.010 '-0254 4 8387 3 3904 35.55 15.559 .250 .5504 - 010 '-0254. 4 7742 3 4894 37.03 15.832 .270 .5858 -.009 ‘-0229 4 7097 3 5739 30.83 14.014 .275 .5985 -.009 “~0229 4 6774 2-9961 21.80 9 909 .272 .5909 -.010 '~0254 4 6967 2~1098 12.78 5.809 .258 .5807 -.013 ‘-0330 4.7226 l 2300 5.83 2.550 .251 .5529 -.017 “.0432 4 7678 .5558 1.50 .582 .252 .5401 -.019 “~0483 4 8257 .1413 0.0 0.0 .248 .5299 .020 -.0508 4 8517 0-0 9.77 4.441 .250 .5350 .020 -.0508 4 8387 ~9178 19.17 8.714 .255 .5502 .020 “.0508 4 8001 l 8154 27.44 12 473 .254 .5705 .018 -.0457 4 7483 2-6268 35 34 15.054 .275 .6985 .015 “.0381 ~ 4 6774 3-4344 37.78 17.173 .285 .7239 .014 -.0355 4 6129 3.7228 Failure assumed at 20% lateral displacement. *After consol1dat10n. 229 , TABLE C.12 DIRECT SHEAR TEST DATA,SAMPLE $12 Mater1al: Dry fibers groung to powdered form. Normal stress = .962 kg/cm Initial void ratio = 5.6267 Dry density*= 14.50 pcf Water content*= ...% Consolidation Pr = .962 kg/cm2 Load Load Lateral Vertical Are? Shear (lbs) (kg) Displacement Displacement (cm ) Stress (kg/cmZ) (in) (cm) (in) (cm) 2.63 1.196 .003 .0076 0.0 0.0 6.4323 .1859 4.14 1.882 .008 .0203 -.002 —.0051 6.4000 .2941 5.64 2.564 .013 .0330 -.004 -.0102 6.3678 .4027 6.77 3.077 .020 .0508 -.005 -.0127 6.3226 .4867 8.27 3.759 .030 .0762 ‘ -.009 -.0229 6.2581 .6007 9.21‘ 4.186 .040 .1016 -.010 -.0254 6.1935 .6759 10.15 4.614 .054 .1372 -.010 9.0254 6.1031 .7560 10.90 4.955 .075 .1905 -.011 -.0279 5.9677 .8303 12.22 5.555 .100 .2540 -.011 -.0279 5.8064 .9567 12.78 5.809 .120 .3048 -.011 -.0279 5.6774 1.0232 13.35 6.068 .140 .3556 -.011 -.0279 5.5484 1.0936 13.91 6.323 .165 .4191 -.011 -.0279 5.3871 1.1737 14.29 6.495 .190 .4826 -.011 -.0279 5.2258 1.2429 14.66 6.664 .200 .5080 -.011 -.0279 5.1613 1.2911 15.04 6.836 .230 .5842 -.011 -.0279 4.9677 1.3761 15.23 6.923 .260 .6604 -.010 -.0254 4.7742 1.4501 15.41 7.005 .285 .7239 -.010 -.0254 4.6129 1.5186 15.60 7.091 .300 .7620 -.010 -.0254 4.5161 1.5702 Failure assumed at 20% lateral displacement. *After consolidation. 230 TABLE C.13 DIRECT SHEAR TEST DATA, SAMPLE $13 Material: Dry fiber ground 50 powdered form Normal stress = 1.584 kg/cm Initial void ratio = 4.6331 Dry density*= 17.06 pcf Water content*= ...% Consolidation Pr = 1.584 kg/cm2 Load Load Lateral Vertical Area Shear (lbs) ' (kg) Displacement Displacement (cm ) Stress , (kg/cmz) (in) (cm) (in) (cm) 5.54 2.554 .003 .0075 -.001 -.0025 5.4323 .3985 8.46 3.845 .008 .0203 -.002 -.0051 6.4000 .6008 11.09 5.041 .016 .0406 -.003 -.0076 6.3485 .7940 12.97 5.895 .025 .0635 -.004 -.0102 6.2903 .9372 14.66 6.664 .035 .0889 -.005 -.0127 6.2258 ‘ 1.0704 15.60' 7.091 .045 .1143 -.006 -.0152 6.1613 1.1509 16.92 7.691 .060 .1524 -.007 -.0178 6.0645 1.2682 17.67 8.032 .075 .1905 -.007 -.0178 5.9677 1.3459 18.98 8.627 .100 .2540 -.007 -.0178 5.8064 1.4858 19.92 9.055 .125 .3175 -.007 -.0178 5.6452 1.6040 20.86 9.482 .145 .3683 -.007 -.0178 5.5161 1.7189 21.80 9.909 .170 .4318 -.007 -.0178 5.3548 1.8505 22.74 10.336 $200 .5080 -.007 -.0178 5.1613 2.003 23.49 10.677 .220 .5588 -.007 -.0178 5.0322 2.1217 24.44 11.109 .250 .6350 -.006 -.0152 4.8387 2.2959 24.81 11.277 .270 .6858 -.006 -.0152 4.7097 2.3944 25.19 11.450 .290 .7366 -.006 -.0152 4.5806 2.4997 25.56 11.618 .300 .7620 -.006 -.0152 4.5161 2.5726 Failure assumed at 20% lateral displacement. *After consolidation. 231 TABLE C.14 DIRECT SHEAR TEST DATA, SAMPLE Sl4 Material: Dry fibers groung to powdered form. Normal stress = 2.21 kg/cm Initial void ratio = 4.290 Dry density*= 18.17pcf" Water Content*’= ...% Consolidation Pr = 2.21 kg/cm2 Load Load Lateral Vertical Areg Shear (lbs) (kg) Displacement Displacement (cm ) Stress (kg/cmz) (in) (cm) (in) (cm) 8.54 3.927 .007 .0178 - 001 - 0025 5.4054 .5129 11.09 5.041 .011 .0279 -.003 -.0076 6.3807 .7900 13 72 5.235 .019 .0483 -.004 -.0102 5.3289 .9353 15.35 7.432 .027 .0585 - 005 -.o152 5 2774 1.1339 18.98 8.527 .040 ..1015 -.008 -.0203 5.1935 1.3929 20.67‘ 9.395 .050 .1270 -.008 -.0203 6.1290 1.5329 22.74 10.335 .055 .1551 5.009 - 0229 5.0322 1.7135 24.44 11.109 .080 .2032 -.009 -.0229 5.9355 1.8716 25.75 11.705 .090 .2286 -.010 '-.0254 5.8709 1.9937 25.50 12.045 .100 .2540 -.010 -.0254 5.8054 2.0744 28.19 12.814 .120 .3048 -.010 -.0254 5.6774 2.2570 29.88 13.582 .140 .3555 - 010 -.0254 5.5484 2.4479 30.64 13.927 .150 .3810 -.009 -.0229 5.4839 2.5396 31.20 14.182 .160 .4064 -.009 -.0229 5.4193 2.6169 32.14 14.609 .175 .4445 -.009 -.0229 . 5.3226 2.7447 33.08 15.035 .190 .4825 -.009 -.0229 5.2258 2 3773 34.02 15.454 .205 .5207 -.009 -.0229 5.1290 3.0150 35.34 16.064 .225 .5715 -.009 -.0229 4.9999 3.2129 36.47 16.577 .240 .6096 -.009 -.0229_ 4.9032 3.3809 36.84 16.745 .250 .6350 -.009 -.0229 4.8387 3.4606 37.59 17.086 .262 .6655 -.009 -.0229 4.7612 3.5886 38.15 17.341 .275 .6985 -.008 -.0203 4.6774 3.7074 38.72 17.600 .285 .7239 -.008 -.0203 4.6129 3.8154 39.25 17.841 .300 .7620 -.007 -.0178 4.5161 3.9505 Failure assumed at 20% lateral displacement. *After c0nsol1dat10n. Material: Dry fiber ground TABLE C.15 DIRECT SHEAR TEST DATA, SAMPLE 'S15 2 to powdered form Normal stress - 2.83 kg/cm Initial void ratio 4.0662 Dry density*= 18.97 pcf 2 Water content*= ...% Consolidation Pr = 2.83 kg/cm Load Load Lateral Vertical Areg Shear (lbs) (kg) Displacement Displacement cm ) Stress (kg/cmz) (in) (cm) (in) (cm) 6.20 2.818 .003 .0076 0.0 0.0 6.4323 .4381 10.15 4.614 .005 .0127 0.0 0.0 6.4193 .7188 12.78 5.809 .007 .0178 0.0 0.0 6.4064 .9067 15.22 6.918 .011 .0279 -.001 -.0025 6.3807 1.0842 17.67 8.032 .015 .0381 -.002 -.0051 6.3548 1.2639 20.30 9.227 .021 .0533 -.003 -.0076 6.3162 1.4608 22.74 10.336 .028 .0711 -.003 -.0076 6.2710 1.6482 25.18 11.445 .040 .1016 -.004 -.0102 6.1935 1.8479 26.69 12.132 .050 .1270 -.004 -.0102 6.1290 1.9794 28.57 12.986 .065 .1651 -.004 -.0102 6.0322 2.1528 29.70 13.500 .080 .2032 -.005 -.0127 5.9355 2.2745 31.20 14.182 .100 .2540 -.005 -.0127 5.8064 2.4425 32.52 14.782 .120 .3048 -.005 -.0127 5.6774 2.6036 33.27 15.123 .135 .3429 -.005 -.0127 5.5806 2.7099 33.82 15.373 .150 .3810 -.004 -.0102 5.4839 2.8033 34.58 15.718 .165 .4191 -.004 -.0102 5.3871 2.9177 35.52 16.145 .180 .4572 -.004 «.0102 5.2903 3.0518 36.47 16.577 .200 .5080 -.004 -.0102 5.1613 3.2118 37.96 17.255 .220 .5588 -.004 —.0102. 5.0322 3.4289 38.91 17.686 .240 .6096 -.004 -.0102 4.9032 3.6070 40.22 18.282 .260 .6604 -.004 -.0102 4.7742 3.8293 41.66 18.936 .280 .7112 -.003 -.0076 4.6452 4.0765 41.73 18.968 .300 _ .7620 -.003 -.0076 4.5161 4.2000 42.10 19.136 .310 .7874 -.003 -.0076 4.4516 4.2987 Failure assumed at 20% lateral displacement. *After consol1dation. Water content*= .. TABLE C.16 DIREST SHEAR TEST DATA, SAMPLE S16 Material: Dry fiber groundzto powdered f Normal stress = Dry density* =20.51 pcf 3.452 kg/cm .% Consolidation Pr - 3.452 kg/cm2 orm Initial void ratio - 3.6849 Load Load Lateral Vertical Ares Shear (lbs) (kg) Displacement Displacement (cm ) Stress (kg/cmz) (in) (cm) (in) (cm) 6.39 2.905 .002 .0051 0.0 0.0 6.4386 .4512 11.65 5.295 .005 .0127 -.002 -.0051 6.4193 .8249 14.66 6.664 .008 .0203 -.002 -.0051 6.4000 1.0413 17.29 7.859 .010 .0254 -.003 -.0076 6.3871 1.2304 19.92 9.055 .015 .0381 -.004 -.0102 6.3548 1.4249 22.55 10.250 .019 .0483 -.005 -.0127 6.3289 1.6196 25.56 11.618 .025 .0635 -.006 -.0152 6.2903 1.8469 28.19 12.814 .033 .0838 -.007 -.0178 6.2387 2.0539 31.01 14.095 .045 .1143 -.008 -.0203 6.1613 2.2877 33.64 15.291 .060 .1524 -.009 -.0229 6.0645 2.5214 36.28 16.491 .082 .2083 -.010 -.0254 5.9225 2.7845 37.97 17.259 .100 .2540 9.010 -.0254 5.8064 2.9724 39.47 17.941 .120 .3048 -.010 -.0254 5.6774 3.1601 40.78 18.536 .140 .3556 -.011 2.0279 5.5484 3.3408 42.29 19.223 .165 .4191 -.011 -.0279 5.3871 3.5683 43.61 19.823 .190 .4826 “.010 -.0254 5.2258 3.7933 43.98 19.991 .200 .5080 -.010 -.0254 5.1613 3.8732 44.36 20.164 .205 .5207 -.010 -.0254 5.1290 3.9314 45.48 20.673 .230 .5842 -.010 -.0254. 4.9677 4.1615 46.42 21.100 .245 .6223 -.010 -.0254 4.8709 4.3318 46.80 21.273 .255 .6477 -.010 -.0254 4.8064 4.4259 47.36 21.527 .270 .6858 -.010 -.0254 4.7097 4.5708 47.74 21.700 .280 .7112 -.010 -.0254 4.6452 4.6715 48.49 22.041 .300 .7620 -.010 -.0254 4.5161 4.8805 Failure assumed at 20% lateral displacement. *After consolidation. 1 234 TABLE C. 17 DIRECT SHEAR TEST DATA, SAMPLE $17 Material: Dry fibers 5groung to powedered form , , Normal stress = g/ cm In1t1a1 v01d rat1o = 3.5256 Dry density*'= 21. 4237 pcf Water content*= ...% Consolidation Pr = 4.075 kg/cm2 Load Load Lateral Vertical Area) Shear (lbs) (kg) Displacement Displacement Stress . (kg/cmz) (in) (cm) (in) (cm) 6.76 3.073 .002 .0051 -.001 -:0025 6.4386 .4773 9.96 4.527 .004 .0102 -.001 -=0025 6.4257 .7045 12.96 5.891 .007 .0178 -.002 -30051 6.4064 .9195 15.98 7.264 .010 1 .0254 -.003 -50076 6.3871 1.1373 18.79 8.541 .013 .0330 -.004 -n0102 6.3678 1.3413 21.80" 9.909 .016 .0406 -.006 -:0152 6.3485 1.5608 25.18 11.445 .022 .0559 -.007 -n0178 6.3096 1.8139 28.00 12.727 .027 .0686 -.009 -a0229 6.2774 2.0274 30.64 13.927 .034 .0864 -.010 -a0254 6.2321 2.2347 33.08 15.036 .043 .1092 -.012 -30305 6.1742 2.4353 36.09 16.405 .059 .1499 -.014 -a0356 6.0709 2.7022 38.72 17.600 .084 .2134 ‘-.015 -.0381 5.9096 2.9782 39.85 18.114 .100 .2540 -.016 -30406 5.8064 3.1197 41.54 18.882 .124 .3149 -.016 '30406 5.6518 3.3409 42.48 19.309 .140 .3556 -.016 '50406 5.5484 3.4801 43.98 19.991 .165 .4191 -.016 -a0406 5.3871 3.7109 44.73 20.332 .180 .4572 -.017 'n0432 5.2903 3.8433 46.24 21.018 .200 .5080 -.017 -z0432 5.1613 4.0722 47.36 21.527 .220 .5588 -.017 “30432 5.0322 4.2779 48.12 21.873 .235 .5969 -.017 '20432 4.9355 4.4318 48.30 21.955 .265 .6731 -.017' '20432 4.7419 4.6300 48.30 21.955 .270 .6858 -.017 ‘30432 4.7097 4.6617 48.31 21.959 .275 . .6985 -.017 7.0432 4.6774 4.6947 48.31 21.959 .300 .7620 -.017 -.0432 4.5161 4.8624 Failure assumed at 20% lateral displacement. *After consolidation. 235 TABLE C.18 DIRECT SHEAR TEST DATA, SAMPLE $18 Material: Dry fibers groundzto powdered form Normal stress = 4.686 kg/cm Initial void ratio = 3.2845 Dry density*fi 22.43 pcf Water content*5 ...% Consolidation Pr = 4.686 kg/cm2 Load Load Lateral Vertical Area Shear (lbs) (kg) Displacement Displacement (cm ) Stress (kg/cmZ) (in) (cm) (in) (cm) 7.14 3.245 .002 .0051 0.0 0,0 5,4335 .5040 13.72 6.236 .004 .0102 0.0 0.0 5.4257 .9705 19.74 8.973 .007 .0178 -.001 -.0025 5,4054 1.4005 25.56 11.618 .011 .0279 -.002 -.0051 5.3307 1.3203 31.20 14.182 .016 .0406 -.003 -.0075 5.3435 2.2339 34.02' 15.464 .020 .0508 -.004 -,0102 5.3225 2,4453 36.84 16.745 .025 .0635 -.004 -.0102 5.2903 2.5520 39.47 17.941 .030 .0752 -.005 -.0127 6.2581 2.8668 42.85 19.477 .040 ~1016 -.006 -.0152 6.1935 3.1447 46.99 21.359 .060 -1524 -.007 -.0178 6.0645 3.5219 48.49 22.041 .070 .1778 -.007 -.0178 5.9999 3.5735 50.37 22.895 .085 -2159 -.007 -.0178 5.9032 3.8784 52.26 23.755 .100 .2540 -.007 -.0178 5.8054 4.0912 54.32 24.691 .120 .3048 -.007 -.0178 5.6774 4.3490 55.64 25.291 .140 .3556 -.007 -.0178 5.5484 4.5583 57.14 25.973 .160 -4064 -.007 -.0178 5.4193 4.7927 57.89 26.314 .170 .4318 -.007 -.0178 5.3548 4.9141 58.65 26.659 .180 .4572 -.007 -.0178 . 5.2903 5.0392 60.71 27.595 .200 .5080 -.007 -.0173. 5,1513 5.3455 63.16 28.709 .230 .5842 -.006 -.0152 4.9677 5.7791 65.03 29.559 .250' .6350 -.006 -.0152 4.8387 6.1089 66.73 30.332 .270 .5858 -.006 —.0152 4.7097 6.4403 68.42 31.100 .290 '. .7356 -.005 -.0127 4.5806 6.7895 69.36 31.527 .300 .7620 -.005 -.0127 4.5161 6.9810 Failure assumed at 20% lateral displacement. *After consolidation. ‘ Material: TABLE C.19 DIRECT SHEAR TEST DATA, SAMPLE S19 Dry fibers groun Normal stress - 6.550 kg/cm Dry density*= 24.14 pcf Water content*= .. .% E to powdered form Initial void ratio Consolidation Pr 2. 9808 6.550 kg/cm2 Load Load Lateral Vertical Are? Shear (lbs) (kg) Displacement Displacement (cm ) Stress . (kg/cmz) (1n) (cm) (in) (cm) 17.85 8.114 .004 .0102 -.001 .0025 6.4257 1.2627 37.21 16.914 .013 .0330 -.005 .0127 6.3678 2.6562 51.12 23.236 .025 .0635 -.006 .0152 6.2903 3.6939 53.38 24.264 .029 .0737 -.006 .0152 6.2644 3.8733 56.10 25.500 .033 .0838 -.007 .0178 6.2387 4.0874 58.45 26.568 .039 .0991 -.007 .0178 6.1999 4.2852 61.27 27.850 .047 .1194 -.008 .0203 6.1483 4.5297 63.72 28.964 .057 .1448 -.009 .0229 6.0838 4.7608 66.16 30.073 .072 .1829 -.009 .0229 5.9870 5.0230 67.66 30.755 .085 .2159 -.010 .0254 5.9032 5.2099 69.92 31.782 .100 .2540 -.010 .0254 5.8064 5.4736 71.99 32.723 .115 .2921 -.010 .0254 5.7097 5.7311 73.87 33.577 .130 .3302 -.010 .0254 5.6129 5.9821 75.75 34.432 .145 .3683 -.010 .0254 5.5161 6.2421 77.25 35.114 .160 .4064 -.010 .0254 5.4193 6.4794 78.94 35.882 .175 .4445 -.010 .0254 5.3226 6.7414 80.07 36.395 .185 .4699 -.009 .0229 5.2581 6.9217 81.58 37.082 .200 .5080 -.009 .0229 5.1613 7.1846 83.45 37.932 .220 .5588 -.010 .0254 5.0322 ’ 7.5379 85.71 38.959 .240 .6096 -.009 .0229 4.9032 7.9456 86.84 39.473 .255 .6477 -.009 .0229 4.8064 8.2126 88.15 40.068 .270 .6858 -.009 .0229 4.7097 8.5075 89.47 40.668 .285 .7239 9.009 .0229 4.6129 8.8161 90.60 41.182 .300 .7620 -.009 .0229 4.5161 9.1189 Failure assumed at 20% lateral displacement. *After consolidation. 237 TABLE C.20 DIRECT SHEAR TEST DATA, SAMPLE $20 Material: Saturated fiberszground to powdered form Normal stress = 1.584 kg/cm Dry density*= 24.89 pcf Water contentv'c= 185% Consolidation Pr = 1.584 kg/cm2 Load Load Lateral Vertical Area Shear (lbs) (kg) Displacement Displacement (cm ) Stress (kg/cmZ) (in) (cm) (in) (cm). 3.01 1.368 .003 .0076 -.002 -.0051 6.4323 .2127 6.01 2.732 .008 .0203 -.001 -.0025 6.4000 .4269 12.03 5.468 .012 .0305 -.001 -.0025 6.3741 .8578 14.66 6.664 .017 .0432 -.001 -.0025 6.3419 1.0508 17.48 7.945 .028 .0711 -.002 -.0051 6.2710 1.2669 19.73‘ 8.968 .055 .1397 -.002 -.0051 6.0968 1.4709 20.30 9.227 .070 .1778 -.002 -.0051 5.9999 1.5379 21.05 9.568 .100 .2540 -.001 -.0025 5.8064 1.6478 21.62 9.827 .115 .2921 -.001 -.0025 5.7097 1.7211 22.36 10.164 .140 .3556 -.001 -.0025 5.5484 1.8319 23.12 10.509 .160 .4064 0.0 0.0 5.4193 1.9392 23.68 10.764 .180 .4572 0.0 0.0 5.2903 2.0347 24.44 11.109 .200 .5080 0.0 0.0 5.1613 2.1524 25.00 11.364 .220 .5588 -.001 -.0025 5.0322 2.2583 25.56 11.618 .240 .6096 -.001 -.0025 4.9032 2.3695 56.50 12.045 .260 .6604 +.001 +.0025 4.7742 2.5229 27.06 12.300 .290 .7366 +.002 +.0051 4.5806 2.6852 27.44 12.473 .300 .762 +.002 +.0051 4.5161 2.7619 Failure assumed at 20% lateral displacement. *After consolidation. 238 TABLE C.21 DIRECT SHEAR TEST DATA, SAMPLE $21 Material: Saturated fibers ground to powdered form Normal stress = 2.206 kg/cm Dry density*= 27.83 pcf Water content*= 159% 2.206 kg/cm2 Consolidation Pr Load Load Lateral Vertical Are? Shear (lbs) (kg) Displacement Displacement (cm ) Stress ~ (kg/cmz) (in) (cm) (in) (cm) 5.45 2.477 .002 .0051 0.0 0.0 6.4386 .3847 8.27 3.759 .007 .0178 -.002 -.0051 6.4064 .5868 11.27 5.123 .014 .0356 -.003 -.0076 6.3612 .8054 14.09 6.405 .024 .0609 -.004 -.0102 6.2969 1.0172 16.72 7.600 .035 .0889 -:005 -.0127 6.2258 1.2207 19.73' 8.968 .050 .1270 -.006 -.0152 6.1290 1.4632 22.55 10.250 .070 .1778 -.007 -.0178 5.9999 1.7084 24.24 11.018 .085 .2159 -.008 -.0203 5 9032 1.8554 25.56 11.618 .100 .2540 -.008 -.0203 5.8064 2.0009 26.69 12.132 .115 2.921 -.008 -.0203 5.7097 2.1248 27.44 12.473 .130 .3302 -.008 -.0203 5.6129 2.2222 28.75 13.068 .150 .3810 -.008 -.0203 5.4839 2.3829 29.69 13.495 .170 .4318 -.008 -.0203 5.3548 2.5202 30.64 13.927 .190 .4826 -.007 -.0178 5.2258 2.6650 31.01‘ 14.095 .200 .5080 -.007 -.0178 5.1613 2.7309 31.76' 14.436 .215 .5461. -.006 -.0152 5.0645 2.8504 32.70 14.864 .240 .6096 -.004 -.0102 4.9037 3.0315 33.08 15.036 .250 .6350 -.004 -.0102 4.8387 3.1074 33.64 15.291 .265 .6731 ’-.002 -.0051 4.7419 3.2247 33.83 15.377 .285 .7239 0.0 0.0 4.6129 3.3335 34.21 15.55 .300 .7620 0.0 0.0 4.5161 3.4432 Failure assumed at 20% lateral displacement. *After consolidation. Material: TABLE C.22 DIRECT SHEAR TEST DATA, SAMPLE $22 Saturated fiber Normal stress - 2.830 kg/cm Dry density*= 26.04 pcf ground to powdered form. Water content*5 175% Consolidation Pr = 2.830 kg.cm2 Load Load Lateral Vertical Are? Shear (lbs) (kg) Displacement Displacement (cm ) Stress - (kg/cmz) (in) (cm) (in) (cm) 6.76 3.073 .002 .0051 0.0 0.0 6.4386 .4773 9.77 4.441 .005 .0127 0.0 0.0 6.4193 .6918 12.40 5.636 .009 .0229 0.0 0.0 6.3934 .8815 15.22 6.918 .015 .0381 -.001 -.0025 6.3548 1.0886 18.04 8.200 .025 .0635 -.002 -.0051 6.2903 1.3036 23.30' 10.591 .047 .1194 -.002 -.0051 6.1483 1.7226 26.12 11.873 .063 .1600 -.003 -.0076 6.0452 1.9640 28.38 12.900 .080 .2032 -.003 -.0076 5.9355 2.1734 30.45 13.841 .100 .2540 -.003 -.0076 5.8064 2.3837 32.33 14.695 _ .120 .3048 -.003 -.0076 5.6774 2.5883 34.21 15.550 .144 .3658 -.002 -.0051 5.5225 2.8157 35.34 16.064 .160 _ .4064 -.002 -.0051 5.4193 2.9642 36.46 16.573 .175 .4445 -.002 -.0051 5.3226 3.1137 37.59 17.086 .200 .5080 -.002 -.0051 5.1613 3.3104 38.91 17.686 .210 .5334 -.002 -.0051 5.0968 3.4700 40.60 18.455 .230 .5842 -.001 -.0025 4.9677 3.7150 41.16 18.709 .245 .6223 0.0 0.0 4.8709 3.8409 41.92 19.055 .260 . .6604 +.001 +.0025 4.7742 3.9912 42.66 19.391 .270 .6858 +.003 _ +.0076. 4.7097 4.1172 43.04 19.564 .280 .7112 +.004 +.0102 4.6452 4.2117 43.98 19.991 .300 .7620 +.006 +.0152 4.5161 4.4266 44.36 20.164 .310 .7874 +.008 +.0203 4.4516 4.5296 44.54 20.245 .320 , .8128 +.009 +.0229 4.3871 4.6147 Failure assumed at 20% lateral displacement. *After consolidation. Material: Saturated fibers Normal stress = 4.075 kg/cm TABLE C.23 DIRECT SHEAR TEST DATA, SAMPLE $23 Dry density*= 28.12 pcf Water content*= 157% ground to powdered form Consolidation Pr = 4.075 kg/cm2 Load Load Lateral Vertical Ares Shear (lbs) (kg) Displacement Displacement (cm ) Stress . (kg/cmz) (1n) (cm) (in) (cm) 6.01 2.732 .003 .0076 0.0 0.0 6.4323 .4247 8.83 4.014 .006 .0152 -.001 -.0025 6.4130 .6259 11.65 5.295 .009 .0229 -.001 -.0025 6,3934 .8282 14.66 6.664 .014 .0356 -.002 -.0051 6.3612 1.0476 17.48 7.945 .020 .0508 -.002 -.0051 _ 6.3226 1.2566 20.30‘ 9.227 .027 .0686 -.003 -.0076 6.2774 .14699 22.93 10.423 .035 .0889 -.004 -.0102 6.2258 1.6742 25.94 11.791 .044 .1118 —.004 -.0102 6.1676 1.9118 28.38 12.900 .055 .1397 -.005 -.0127 6.0968 2.1159 31.01 14.095 .068 .1727 -.006 -.0152 6.0129 2.3441 33.83 15.377 .083 .2108 -.006 -.0152 5.9162 2.5991 36.28 16.491 .100 , .2540 -.006 -.D152 5.8064 2.8401 37.21 16.914 .110 .2794 -.006 -.0152 5.7419 ‘2.9457 38.72 17.600 .120 .3048 -.006 -.0152 5.6774 3.1000 41.16 18.709 .140 .3556 -.006 -.0152 5.5484 3.3720 42.10 19.136 .155 .3937 -.006 -.0152 5.4516 3.5102 43.98 19.991 .174 .4419 -.007 -.0152 5.3292 3.7512 46.62 21.191 .200 .5080 -.007 -.0178 5.1613 4.1057 48.12 21.873 .220 .5588 -.007 -.0178. 5.0322 4.3466 49.62 22.555 .240 .6096 -.007 -.0178 4.9032 4.6000 51.32 23.327 .260 .6604 -.007 -.0178 4.7742 4.8861 54.88 24.945 .300 .7620 -.007 -.0178 4.5161 5.5236 55.82 25.373 .310 , .7874 -.007 -.0178 4.4516 5.6997 56.39 25.632 .320 .8182 -.007 -.0178 4.3734 5.8609 Failure assumed at 20% lateral displacement. *After consolidation. 241 TABLE C.24 DIRECT SHEAR TEST DATA, SAMPLE ' 24 Material: Saturated fiber r5 ground to powdered form. Normal stress = 6. 55 kg/cm Dry density*= 35.07 POT Water content""= 112% Consolidation Pr = 6.55 kg/cm2 Load Load Lateral Vertical Are? Shear (lbs) (kg) Displacement Displacement (cm ) Stress * (kg/cmz) (in) (cm) (in) (cm) 6.39 2.905 .002 .0051 0.0 0.0 6.4386 .4512 16.35 7.432 .004 .0102 0.0 0.0 6.4257 1.1566 22.56 10.255 .006 .0152 0.0 0.0 6.4130 1.5991 28.38 12.900 .010 .0254 -.006 -.0157 6.3871 2.0197 31.20 14.182 .012 .0305 -.001 -.0025 6.3741 2.2249 37.22‘ 16.918 .017 .0432 -.002 -.0051 6.3419 2.6677 42.85 19.477 .024 .0610 -.002 -.0051 6.2967 3.0932 46.62 21.191 .030 .0762 -.003 -.0076 6.2581 3.3862 51.88 23.582 .040 .1016 -.003 -.0076 6.1935 3.8075 56.39 25.632 .052 .1321 -.003 -.0076 6.1161 4.1909 58.83 26.741 .060 .1524 -.003 -.0076 6.0645 4.4094 61.09 27.768 .068 .1727 -.003 -.0076 6.0129 4.6181 63.15 28.705 .080 .2032 -.003 -.0076 5.9355 4.8362 65.41 29.732 .090 .2286 —.003 -.0076 5.8709 5.0643 68.04 30.927 .100 .2540 -.003 -.0076 5.8064 5.3264 71.42 32.464 .120 .3048 -.003 -.0076 5.6774 5.7181 73.87 33.577 .137 .3480 -.002 -.0051 5.5677” 6.0307 75.94 34.518 .153 .3886 -.002 -.0051 5.4646 6.3167 77.25 35.114 .165 .4191- —.002 -.0051. 5.3871 6.5182 79.51 36.141 .185 .4699 -.001 -.0025 5.2581 6.8734 81.58 37.082 .200 .5080 0.0 0.0 . 5.1613 7.1846 84.21 38.277 .233 .5918 +.003 +.0076 4.9484 7.7352 85.71 38.959 .260 .6604 +.005 +.0127 4.7742 8.1603 Failure assumed at 20% lateral displacement. *After consolidation. 242 TABLE C.25 DIRECT SHEAR TEST DATA, SAMPLE $25 Material: Saturated fibers ground to powdered form. Normal stress = 5. 304 kg/cm Dry density*= 31. 71 pcf Water content*=l32% Consolidation Pr = 5.304 kg/cm2 Load Load Lateral Vertical Are? Shear (lbs) (kg) Displacement Displacement ) Stress (kg/cmz) (in) (cm) (in) (cm) 6.20 2.818 .003 .0076 0.0 0.0 6.4323 .4381 18.23 8.286 .009 .0229 -.001 -.0025 6.3934 1.2960 23.49 10.677 .015 .0381 -.002 -.0051 6.3548 1.6801 28.75 13.068 .024 .0610 -.003 -.0076 6.2967 2.0754 33.83 15.377 .035 .0889 -.004 - 0102 6.2258 2.4699 39.28' 17.855 .050 .1270 -.005 -.0127 6.1290 2.9132 43.98 19.991 .068 .1727 -.005 -.0127 6.0129 3.3247 46.99 21.359 .080 .2032 -.005 -.0127 5.9355 3.5985 49.06 22.300 .090 .2286. -.005 -.0127 5.8709 3.7984 50.56 22.982 .100 .2540 -.005 -.0127 5.8064 3.9580 54.13 24.605 .120 .3048 -.005 -.0127 5.6774 4.3339 56.95 25.886 .140 .3556 -.005 -.0127 5.5484 4.6655 58.83 26.741 .155 .3937 -.005 -.0127 5.4516 4.9052 60.52 27.509 .177 .4496 -.004 -.0102 5.3096 5.1810 62.40 28.364 .185 .4699 -.004 -.0102 5.2581 5.3943 64.28 29.218 .200 .5080 -.004 -.0102 5.1613 5.6610 66.91 30.414 .222 .5639 -.004 -.0102 5.0193 6.0594 68.23 31.014 .235 .5969 -.003 -.0076 4.9355 6.2839 69.36 31.527 .250 .6350 -.002 -.0051 4.8387 6.5156 71.24 32.382 2. 70 .6858 -.001 -.0025 4.7097 6.8756 72.93 33.150 .290 .7366 0.0 0.0 4.5806 7.2370 74.06 33.664 .300 .7620 +.001 +.0025 4.5161 7.4542 75.18 34.173 .315 .8001 +.001 +.0025 4.4193 7.7327 Failure assumed at 20% lateral displacement. *After consolidation. ._. 243 TABLE D.1 TRIAXIAL TEST DATA, SAMPLE CU-1 'KAOLINITE Consolidation pressure = 2.0 kg/cm2 Angle between direction of compression and horizontal = 90° 0 = 3.534 kg/cmz A = .23 11, f ‘3 = 1.520 kg/cm2 Water content* = 29.21% f 2 Dry density* = 93.21 pcf Uf = .48 kg/cm koa? Displacement Pore Axial 61 53 kg cm Pressure Strain. 2 2 , (kg/cmz) (%) (kg/cm ) (kg/cm ) 0.0 0.0 0.0 0.0 2.00 2.00 1.17 .05842 .01 0.756 2.099 1.99 6.31 .11938 .10 1.546 2.485 1.90 10.72 .16764 .25 2.171 2.739 1.75 15.27 .27432 .50 3.552 2.899 1.50 16.88 .33528 .55 4.341 2.973 1.45 18.20 .39116 .60 5.064 3.029 1.40 20.55 .51308 .61 6.644 3.199 1.39 21.87 .60198 .61 7.795 3.291 1.39 .22.75 .65786 .60 8.518 3.362 1.40 23 54 .73152 .55 9.472 3.458 1.45 24.81 .83566 .55 10.820 3.536 1.45 25.10 .88392 .50 11.445 3.595 1.50 25.69 .98298 .48 12.728 3.634 1.52 25.84 1.04648 .46 13.550 3.646 1.54 25.84 1.12776 .43 14-603 3.650 1.57 24.52 1.34366 .33 17.398 3.579 1.67 23.93 1.43510 .34 18.582 3.497 1.66 21.58 1.52908 .33 19.799 3.302 1.67 20.55 1.57480 .34 20.391 3.202 1.66 0] and 63 equal the major and minor effective principal stresses, respectively. Failure taken at maximum deviator stress or at 20% axial strain. *Water content and dry density after consolidation. 244 TABLE D.2 TRIAXIAL TEST DATA, SAMPLE CU-2 KAOLINITE Consolidation pressure = 4.0 kg/cm2 Angle between direction of compression and horizonatal = 90° a] = 5.219 kg/cm2 Af = .55 f _ 2 03f 7 2'52 kg/cm Water content = 28.28% 2 2' Dry density = 94.65 pcf Uf - 1.48 kg/cm %oa? Displac?ment Pore Axial 61 53 kg cm Pressure Strain 2 2 ~ (kg/cmz) (%) (kg/cm ) (kg/cm ) 0.0 0.0 0.0 0.0 4.00 4.00 1.71 .0025 0.0 .032 4.162 4.00 4.57 .0178 .01 .231 4.422 3.99 4.43 .0736 0.0 .954 4.416 4.00 4.29 , .1041 -.04 1.349 4.441 4.04 5.00 .1829 0.0 2.370 4.463 4.00 7.43 .2184 .10 2.830 4.585 3.90 14.14 .2438 .04 3.159 4.946 3.60 17.00 .2667 .60 3.456 4.957 3.40 20.71 .3149 .93 4.080 4.982 3.07 24.14 .3860 1.21 5.003 4.965 2.79 25.43 .4165 1.29 5.397 4.992 2.71 27.43 .4826 1.48 6.254 4.958 2.52 29.71 .5766 1.50 7.472 5.108 2.50 30.71 .6426 1.48 8.327 5.189 2.52 31.43 .7391 1.49 9.577 5.205 2.51 31.71 .7925 1.48 10.269 5.219 2.52 31.71 .8356 1.49 10.828 5.192 2.51 31.57 .8839 1.50 11.454 5.151 2.50 30.57 1.0236 1.39 13.264 5.124 2.61 51 and 53 equal the major and minor effective principal stresses, respectively. Failure taken at maximum deviator stress or at 20% axial strain. *Nater content and dry density after consolidation. 245 TABLE 0.3 TRIAXIAL TEST DATA, SAMPLE CU-3 KAOLINITE Consolidation pressure = 5.50 kg/cmz Angle between direction of compression and horizontal = 90° = 2 0] = 5.409 kg/cm2 Xf _ 9'83 kg/Cm f f “ ° 03 = 2.440kg/cm2 Water content = 27.85% f Dry density = 95.20 pcf Load Displacement Pore Axial 6] 53 P . (kg) (cm) (E§7§;§§ 5‘121" (ks/cmz) (kg/cmz) ‘0.0 0.0 0.0 0.0 5.500 5.50 1.28 .0102 .20 .141 5.450 5.30 5.71 .0254 .52 .352 5.754 4.98 9.57 .0432 . .80 .598 5.817 4.70 11.28 .0584 1.00 .810 5.812 4.50 12.85 .0813 1.24 1.127 5.751 4.25 14.85 .1143 1.50 1.585 5.515 3.90 15.71 .1524 1.94 2.114, 5.480 3.55 19.00 .2235 2.38 3.101 5.281 3.12 20.14_ .2542 2.58 3.554 5.198 2.92 21.57 .3124 2.73 4.334 5.191 2.77 22.85 .3759 2.88 5.215 5.152 2.52 24 14 .4343 2.98 5.025 5.182 2.52‘ 25.14 .4801 3.01 5.559 5.244 2.49 25.28 .5485 3.05 7.511 5.301 2.45 27.14 .5071 3.05 8.421 5.357 2.44 27.85 .5504 3.05 9.151 5 409 2.44 27.57 .7571 3.03 10.541 5.351 2.47 25.57 .8839 2.94 12.252 5.194 2.55 20.43 .9527 2.90 13.354 4.577 2.50 5] and 53 equal the major and minor effective principal stresses, respectively. Failure taken at maximum deviator stress or at 20% ax1al strain. *Nater content and dry density after consolidation. 246 TABLE 0.4 TRIAXIAL TEST DATA, SAMPLE CU-4 -.. KAOLINITE Consolidation pre-sure - 1.50 kg/cm2 Angle between direction of compression and horizontal = 90° = 2.551 kg/cm2 0 U = .46 kg/cm2 1f f 03 = 1.040 kg/cm2 Af ‘ '30 f Water content = 31.05% ’ Dry densitv = 90.71.0cf %oa§ Displacgment Pore Axial 61 53 kg cm Pressu e Strain 2 2 . (kg/cmg) (z) (kg/cm ) kg/cm ) 0.00 0.0000 0.00 0.000 1.500 1.50 2.00 .0127 0.00 .158 1.691 1.50 3.58 .0178 .04 .222 1.802 1.46 5.58 .0279 .14 .348 1.893 1.36 7.00 .0432 .20 .538 1.967 1.30 9.43 .0965 .35 1.203 2.042 1.15 12.00 .1905 .47 2.374 2.153 1.03 13.29 .2718 .49 3.388 2.239. 1.01 14.00 .3251 .50 4.052 2.286 1.00 15.15 .4242 .50 5.287 2.375 1.00 16.15 .5588 .47 6.965 2.469 1.03 16.72 .6274 _ .43 7.819 2.546 1.07. 17.00 .6604 .47 8.231 2.524 1.03 17.43 .7366 .45 9.181 2.566 1.05 17.58 .7798 .46 9.719 2.561 1.04 17.65 .8788 .42 10.954 2.585 1.08 17.79 .9804 .41 12.220 2.585 1.09 17.77 1.1227 .37 13.993 2.594 1.13 17.29 1. 2598 .36 15.703 2.536 1.14 16.72 1.3386 .35 16.684 2.484 1.15 51 and 53 equal the major and minor effective principal stresses, respectively. Failure taken at maximum deviator stress or at 20% axial strain. *Water content and dry density after consolidation. 247 TABLE 0.5 TRIAXIAL TEST DATA, SAMPLE CU-5 .1KA0LINITE Consolidation pressure = 6.50 kg/cm2 Angle between direction of compression and horizontal - 90° o] = 8.184 kg/cm2 Af = .59 f _ 2 Water content = 26.45% 031. ' 4:040 kg/Cm Dry density = 97.21 pcf uf = 2.45 kg/cm2 %:ad Displacement Pore Axial 6] 53 cm Press S ' 9) ‘ 1 (.../.1151 4:1" (kg/5.2) (kg/C.21 0.0 0.0000 0.00 0.000 5.500 5.50 1.43 .0203 .04 .271 5.513 5.45 3.57 .0483 .10 .544 5.781 5.40 8.57 .0505 .20 .805 7.214 5.30 15 71 .0787 .44 1.050 7.838 5.05 20.00 .0955 .51 1.287 8.013 5.89 23.57 .1194 .85 1.592 8.144 5.55 27.85 .1500 1.24 2.134 8.191 5.25 30.00 .1879 1.44 2.507 8.205 5.05 33.57 .2438 1.80 3.253 8.193 4.70 37.43 .3149 2.13 4.201 8.225 4.37 39.85 .3851 2.33 5.149 8.235 4.17 41.14 .5004 2.45 5.574 8.179 4.05 41.57 .5553 2.47 7.419 8.159 4.03 41.93 .5071 2.45 8.097 8.184 4.04 42.14 .5555 2.45 8.877 8.169 4.04 42.28 .7341 2.42 9.791 8.182 4.08 42.00 .8890 2.34 11.858 8.141 4.15 41 14 1.0135 2.29 13.518 8.035 4.21 40.14 1.0759 2.23 14.355 7.955 4.27 5] and 53 equal the major and minor effective principal stresses, respectively. Failure taken at maximum deviator stress or at 20% axial strain. *Nater content and dry density after consolidation. 248 TABLE D.6 TRIAXIAL TEST DATA, SAMPLE CU-6 I " KAOLINITE Consolidation pressure = 6.50 kg/cm2 Angle between direction of compression and horizontal = 90° 01 = 8.176 kg/cmz Af = .62 f - 2 Water content = 29.40% O3f ‘ 3:790 kg/Cm Dry density = 92.95 pcf Uf = 2.71 kg/cm2 toa? Dispzacement Pore Axial a] 53 kg cm Pressure Strain 2 2 . (kg/cmz) (%) (kg/cm ) (kg/cm ) 0.0' 0.0 0.00 0.00 5.500 5.50 2.14. .0102 .04 .138 5.590 5.45 4.28 .0203 .09 .275 5.871 5.41 9.28 .0254 .15 .345 7.337 5.34 13.57 .0330 .29 .449 7.557 5.21 15.42 .0405 .38 .553 7.882 5.12 21.42 .0533 .54 7.25 8.155 5.85 24.28 .0550 .82 .898 8.275 5.68 27.14 .0787 1.00 1.071 8.397 5.50 30.00 .0955 1.22 1.313 8.474 5.28 32.85 .1158 1.47 1.589 8.518 5.03 34.71 .1321 1.51 1.797 8.557 4.89 37.14 .1575 1.80 2.143 8.522 4.70' 39.99 .2438 2.30 3.318 8.372 4.20 41.57 .3277 2.53 4.458 8.255 3.97 42.85 .4293 2.68 5.840 8.174 3.82 43.52 .5004 2.71 5.808 8.175 3.79 44.28 .5095 2.72 8.294 8.151 3.78 43.85 .7087 2.70 9.542 8.075 3.80 34.28 .8001 2.58 10.885 7.215 3.92 51 and 53 equal the major and minor effective principal stresses, respectively. Failure taken at maximum deviator stress or at 20% axial strain. *water content and dry density after consolidation. 249 TABLE 0.7 TRIAXIAL TEST DATA, SAMPLE CU-7 ' ” KAOLINITE Consolidation pressure = 2.50 kg/cm2 Angle between direction of compression and horizontal = 90° o] = 2.848 kg/cm2 Af = .79 f _ 2 Water content = 33.78% 03 “ 1°17“ kg/Cm Dry density = 87.25 pcf Uf = 1.33 kg/cm2 toa? Displac§ment Pore Axial 61 63 kg cm Pressure Strain 2 2 0.00 0.0000 0.00 0.000 2.50 2.50 1.43 .0254 .05 .340 2.594 2.45 5.72 .0356 .18 .477 2.895 2.32 7.15 .0432 .25 .579 2.968 2.25 10.15 .0787 .50 1.056 3.014 2.00 12.86 .1549 .89 2.077 2.882 1.61 14.29 .2311 1.04 3.098 2.859 1.46 15.43 .3200 1.18 4.290 2.812 1.32 16.01 .3734 1.22 5.005 2.817 1.28 16.86 ..4851 1.30 6.503 2.792 1.20 17.29 .5410 1.30 7.252 2.820 1.20 17.79 .6223 1.32 8.342 2.828 1.18 18.15 .6833 1.32 9.161 2.845 1.18 18.43 .7569 1.32 10.147 2.853 1.18 18.61 .8052 1.33 10.793 2.847 1.17 18.72 .8433 1.33 11.304 2.848 1.17 18.75 .8788 1.35 11.781 2.822 1.15 18.15 .9703 1.34 13.007 2.755 1.16 15.72 1.0338 1.32 13.858 2.548 1.18 15.01 1.0465 1.31 14.028 2.493 1.19 5] and 63 equal the major and minor effective principal stresses, respectively. Failure taken at maximum deviator stress or at 20% axial strain. *Water content and dry density after consolidation. 250 TABLE 0.8 TRIAXIAL TEST DATA, SAMPLE CU-8 ,,U KAOLINITE Consolidation pressure - 3.50 kg/cm2 Angle between direction of compression and horizontal = 90° o] = 3.627 kg/cm2 Af = .93 f = 2 Water content = 33.58% O3f 1'700 kg/Cm Dry density = 87.49 pcf Uf = 1.80 kg/cm2 Load Displacement Pore Axial 51 kg cm Pressure Strain 2 (kg/cmz) (%) (kg/cm ) (kg/cm 0.00 0.0000 0.00 0.000 3.500 3. 2.72 .0228 .01 .313 3.737 3.49 5.57 .0254 [.10 .347 3.905 3.40 8.43 .0356 .23 .487 4.034 3.27 11.86 .0533 .45 .730 4.123 3.05 14.14 .0787 .68 1.078 4.093 2.82 17.00 .1295 1.00 1.773 4.021 2.50 18.43 .1702 1.16 2.329 3.979 2.34 19.86~ .2311 1.37 3.164 3.882 2.13 20.86 .2921 1.50 3.998 3.824 2.00 21.57 ..3581 1.61 4.902 3.757 1.89 22.00 .3962 1.67 5.423 3.725 1.83 22.43 .4623 1.72 6.327 3.693 1.78 22.86 .5537 1.81 7.579 3.614 1.69 23.00 .5842 1.80 7.996 3.627 1.70 23.10 .6401 1.83 8.761 3.589 1.67 23.11 .7036 1.87 9.630 3.532 1.63 22.86 .8103 1.90 11.090 3.450 1.60 21.43 .9576 1.90 13.107 3.295 1.60 19.86 1.0719 1.93 14.671 3.114 1.57 6] and 53 equal the major and minor effective principal stresses, respectively. axial strain. *Water content and dry density after consolidation. Failure taken at maximum deviator stress or at 20% 251 TABLE 0.9 IRIAXIAL.TEST DATA, SAMPLE CU-9 KAOLINITE Consolidation pressure - 4.50 kg/cm2 Angle between direction of compression and horizontal = 90° a1 = 4.500 kg/cm2 A1, = 1.0 f _ 2 Water content = 32.336 03 ' 2’210 kg/cm Dry density = 88.9l pcf uf = 2.29 kg/cm2 Load Displacement Pore Axial 5] 53 kg cm Pressure Strain 2 2 . (kg/cmz) (%) (kg/cm ) (kg/cm ) 0.00 0.0000 0.00 0.000 4.500 4.50 4.71 .0038 .11 .053 4.884 4.39 9.00 .0127 .32 .177 5.122 4.18 11.86 .0279 .58 .389 5.158 3.92 14.71 .0533 .86 .742 5.171 3.64 16.86 .0823 1.18 1.144 5.068 3.32 17.57 .0965 1.27 1.342 5.047 3.23 18.29 .1118 1.37 1.554 5.018 3.13 19.00~ .1270 1.48 1.766 4.978 3.02 19.71 .1499 1.59 2.084 4.933 2.91 21.14 .2083 1.80 2.896 4.852 2.70 21.86 .2515 1.95 3.497 4.762 2.55, 22.29 .2921 2.04 4.062 4.702 2.46 22.57 .3302 2.10 4.592 4.658 2.40 23.14 .4013 2.21 5.581 4.580 2.29 23.39 .4749 2.29 6.605 4.500 2.21 23.43 .5080 2.30 7.064 4-483 2.20 23.43 .5486 2.31 7.629 4.463 2.19 21.57 .7289 2.37 10.138 4.162 2.13 19.71 .8229 2.40 11.444 3.929 2.10 5] and 53 equal the major and minor effective principal stresses, respectively. Failure taken at maximum deviator stress or at 20% axial strain. *Water content and dry density after consolidation. 252 TABLE 0.10 TRIAXIAL TEST DATA, SAMPLE CU-FC1 75% KAOLINITE/25% FIBER BY VOLUME Consolidation pressure = 3.0 kg/cm2 Angle between direction of compression and horizontal = 90° o] = 3.958 kg/cm2 Af = .66 f = 2 Water content = 46.71% C3f 1'200 kg/cm Dry density = 70.l6 pcf uf = 1.800 kg/cm2 Load Displacement Pore Axial 6] 53 P . ('59) (cm) £333,158 Star (kg/C.2) (kg/cmz) 0.00 0.0000 0.00 0.000 3.000 3.00 3.71 .0254 0.10 .331 3.385 2.90 8.00 .0406 .30 .529 3.745 2.70 10.85 ' .0686 .54 .894 3.872 2.46 12.28 .0864 .69 1.126 3.904 2.31 15.14 .1448 .98 1.887 3.972 2.02 16.57 .1829 1.14 2.384 3.984 1.86 18.00 .2337 1.29 3.046 4.002 1.71 19.43. .2946 1.42 3.841 4.034 1.58 20.14 .3327 1.50 4.337 4.019 1.50 21.57 . .4445 1.63 5.794 4.039 1.37 22.29 .5309 1.71 6.919 4.016 1.29, 22.71 .5944 1.76 7.747 3.992 1.24 23.00 .6680 1.80 8.707 3.958 1.20 23.33 .7950 1.88 10.363 3.867 1.12 23.46 .8890 1.90 11.588 3.825 1.10 23.57.9322 1.91 12.151 3.809 1.09 23.71 1. 0058 1.95 13.110 3.756 1.05 23.85 1.1176 2.00 14.568 3.676 1.00 24.86 1.3792 2.10 17.978 3.577 .90 5] and 63 equal the major and minor effective principal stresses, respectively. Failure taken at maximum deviator stress or at 20% ax1al strain. *Water content and dry density after consolidation. 253 TABLE 0.11 TRIAXIAL TEST DATA, SAMPLE CU-FCZ 75% KAOLINITE/25% FIBER BY VOLUME Consolidation pressure = 4.50 kg/cm‘ Angle between direction of compression and horizontal = 90° 61 = 5 898 kg/cm? Af = .64 f = 2 Water content = 45.29% O3f 1'95 kg/Cm Dry density = 70.50 pcf u1, = 2.54 kg/cm2 Load Displacement Pore Axial 6] 532 k P ° (9) ‘ (cm) _ 1:332:55: Stigin (kg/6.2) (kg/cm 1 0.00 0.0000 0.00 o 000 4 500 4.50 4.14 .0229 .08 .307 4.890 4.42 7.00 .0483 .15 .647 5.143 4.35 9.86 .0533 f .22 .715 5.396 4.28 14.14 .0660 .38 .886 5.718 4.12 17.00 .0813 .53 1.090 5 887 3.97 19.85 .1041 .77 1.397 5.962 3.73 21.28 .1168 .90 1.567 5.988 3.60 24 14 .1524 1.19 2.044 6.006 3.31 27.00 .1981 1.46 2.657 6.038 3.04 29 14 .2413 1.69 3.237 6.026 2.81 31.57 .3023 1.91 4.054 6.044 2.59 33.43 .3683 .2.10 4.940 6.024 2.40 34.85 .4343 2.24 5.826 6.003 2.26 36 28 .5105 2.38 6.848 5.974 2.12 37.00 .5639 2.44 7.564 5.960 2.06 37.71 .6299 2.54 8.449 5.898 1.96 38.71.8357 2.70 11.209 5.719 1.80 39.07 1. 0973 2.85 14.718 5.449 1.65 39.07 1. 2624 2.95 16.932 5.252 . 1.55 8] and 63 equal the major and minor effective principal stresses, respectively. Failure taken at maximum deviator stress or at 20% axial strain. *Water content and dry density after consolidation. 254 TABLE 0.12 TRIAXIAL TEST DATA, SAMPLE CU—FC3 75% KAOLINITE/25% FIBER BY VOLUME Consolidation pressure = 2.00 kg/cm‘ Angle between direction of compression and horizontal = 90° o] = 2.882 kg/cm2 Af = .58 f = 2 Water content = 51.05% G3f '77 kg/cm Dry density = 66.90 pcf 0f = 1.23 kg/cm2 Load Displacement Pore Axial 51 k c Pr 5 S ' ( 9) ( m) m3 3559 tfgi" (kg/cmz) (kg/cm 0.00 0.0000 0.00 0.000 2.000 2. 4.43 .0102 .10 .147 2.469 1.90 7.29 .0381 .28 .549 2.654 1.72 0.15 .0762 .53 1.099 2.765 1.47 1.58 .1499 .55 2.163 2.801 1.34 13.01 .2134 .80 3.079 2.826 1. 14.43 .3073 .90 4.436 2.879 1. 15.00 .3454 .95 4.986 2.888 1. 15.43 .3810 .99 ~5.499 2.891 1. 16.15 .4521 1.02 6.526 2.927 . 16 57 .5029 1.08 7.259 4 2.903 16.93 .5588 1.09 8.066 2.917 17.29 .6223 1.11 8.983 2.919 17.72 .6909 1.12 9.973 2.937 18.01 ' .7315 1.14 10.559 2.937 18 29 .8128 1.17 11.732 2.913 18 72 .9347 1.20 13.492 2.888 18.93 . .9906 1.21 14.299 2.883 19.29 1. 0465 1.23 15.106 2 882 19.58 1.1455, .1.25 16.535 2.858 5] and 63 equal the major and minor effective principal stresses, respectively. Failure taken at maximum deviator stress or at 20% axial strain. *Water content and dry density after consolidation. -255 TABLE 0.13 TRIAXIAL TEST DATA, SAMPLE CU-FC4 75% KAOLINITE/25% FIBER BY VOLUME Consolidation pressure = 6.00 kg/cm2 Angle between direction of compression and horizontal = 90° o] = 7.279 kg/cm2 A1. = .73 f = 2 Water content = 40.51% O3f 2‘52 kg/cm Dry density = 75.44 pcf Uf =~3.48 kg/cm2 Load Displacement Pore Axial 6] 53 kg cm Pressure Strain 2 2 0.00 0.0000 0.00 70.000 6.000 6.00 3.57 .0203 .05 .265 6.415 5.95 6.43 .0279 .12 ..364 6.715 5.88 10.71 .0457 .35 .596 7.039 5.65 13.57 .0635 .59 .828 7.166 5.41 16 43 .0838 .84 1.093 7.280 5.16 19.28 .1118 1.15 1.457 7.329 4.85 23.71 .1600 1.60 2.086 7.429 4.40 . 26.43 .1981 1.90 2.582 7.459 4.10 29.43 .2515 2.22 3.277 7.494 3.78 32.29 .3124 2.50 4.072 7.542 3150 35.00 .3886 2.78 5.066 7.555 3.22, 36.43 .4343 2.90 5.662 7.583 3.10 37.85 .4851 3.05 6.324 7.575 2.95 39.29 .5842 3.26 7.615 7.476 2.74 40.00 .6756 3.48 8 807 7.279 2.52 40.71 .8001 3.58 10.429 7.178 2.42 41.71 .9652 3.72 12.581 7.037 2.28 42.86 1.1887 3.95 15.496 6.776 2.05 43.86 1.3767 4.14 17.946 6.555 1.86 5] and 53 equal the major and minor effective principal stresses, respectively. Failure taken at maximum deviator stress or at 20% axial strain. *Water content and dry density after consolidation. 256 4 TABLE 0.14 TRIAXIAL TEST DATA, SAMPLE CU-CF1 54% FIBER/46% KAOLINITE BY VOLUME Consolidation pressure = 3.00 kg/cm2 Angle between direction of compression and horizontal = 90° o] = 4.202 kg/cm2 A1, = .63 f - 2 - Water content - 54.28% 03f 7 '94 kg/cm Dry density = 60.36 pcf uf = 2.06 kg/cm2 Load Displacement Pore Axial 6] 53‘ kg cm Pressure Strain 2 2 . (kg/cmZ) (%) (kg/cm ) (kg/cm ) 0.00 0.0000 0.00 0.000 3.000 3.00 8.28 .0381 . .18 .513 3.689 2.82 14.00 .0864 .50 1.164 3.961 2.50 18.71 .1575 .81 2.122 4.124 2.19 24.43 .2972 1.20 4.004 4.277 1.80 26.57 .3759 1.35 5.065 4.314 1.65 28.85 .4902 1.53 6.605 4.315 1.47 30.85 .6172 1.65 8.316 4.337 1335 32.00 .7163 1.71 9.651 4.343 1.29 32.43 .7620 1.74 10.267 4.333 1.26 33.28 ‘ .8611 1.80 11.602 4.307 1.20 33.85 .9373 1.83 12.628 4.293 1.17 34.64 1.0262 1.89 13.826 4.262 1.11 35.00 1.1049 1.91 14.887 4.236 1.09 35.28 1.1532 1.94 15.537 4.207 1.06 35.18 1.2446 2.00 16.769 4.092 1.00 36.90 1.3437 2.00 18.104 4.191 1.00 37.93 1.4453 2.02 19.473 4.175 .95 38.62 1.4859 2.06 20.021 4.202 .94 39.13 1.5215 2.08 20.499 4.205 .92 5] and 53 equal the major and minor effective principal stresses, respectively. Failure taken at maximum deviator stress or at 20% ax1al strain. *water content and dry density after consolidation. 257 TABLE 0.15 TRIAXIAL TEST DATA, SAMPLE CU-CFZ 54% FIBER/46% KAOLINITE BY VOLUME Consolidation pressure = 4.00kg/cm2 Angle between direction of compression and horizontal = 90° 01 = 5.668 kg/cm2 Af = .63 f = 2 Water content = 59.85% O3f 1°14° kg/Cm .Dry density = 57.35 pcf uf = 2.86 kg/cm2 Load Displacement ‘ Pore Axial 5] 53 kg cm Pressu e Strain 2 2 . (kg/cmE) (%) (kg/cm 1 (kg/cm ) 0.00 0.0000 0.00 0.000 4.000 4.00 5.28 .0102 .03 .139 4.579 3.97 11.00 .0432 .22 .592 5.043 3.78 13.85 .0787 .40 1.080 5.182 3.60 16.00 .1067 .54 1.463 5.281 3.46 19.57 .1676 .88 2.299 5.328 3.12 23.57 .2642 1.34 3.623 5.283 2.66 26.43 .3581 1.65 4.911 5.252 2.35 29.43 .4749 1.93 . 6.514 5.247 2.07 31.28 .5791 2.11 7.942 5.216 1.89 32.57 .6706 2.24 9.196 5.176 1.76 34.21 .7976 2.38 10.938 5.139 1.62. 35.25 .8382 2.40 11.495 5.203 1.60 36.62 .8890 2.45 12.192 5.264 1.55 39.37 1.0058 2.55 13.794 5.369 1.45 42.47 1.1328 2.65 15.536 5.493 1.35 44.88 1.2395 2.71 . 16.999 5.592 1.29 46.94 1.3309 2.79 18.253 5.641 1.21 49.01 1.4579 2.86 19.994 5.668 1.14 49.18 1.4834 2.87 20.343 5.654 1.13 61 and 63 equal the major and minor effective principal stresses, respectively. Failure taken at maximum deviator stress or at 20% axial strain. *Water content and dry density after consolidation. 258, TABLE 0.16 TRIAXIAL TEST DATA, SAMPLE CU-CF3 54% FIBER/46% KAOLINITE BY VOLUME Consolidation pressure = 6.00kg/cm2 Angle between direction of compression and horizontal = 90° C 8.659 kg/cm2 A = .61 1f f 03 1.770 kg/cm2 Water content - 56.06% f 2 Dry density = 64.92 pcf Uf = 4.23 kg/cm Load Displacement Pore Axial 6] ‘39) (cm) Pfigiggfif Stfgi" (kg/enZ) (kg/cm2 1 0.00 0.0000 0.00 0.000 6.000 6.00 4.00 .0254 .08 .354 6.474 5.92 9.71 .0356 .19 .495 7.152 5.81 15.43 .0572 .40 .796 7.727 5.60 20.57 .0914 .72 1.274 8.101 5.28 26.14 .1448 1.27 2.017 8.288 4.73 31.53 .2209 1.98 3.078 8.266 4.02 44.25 .3073 2.64 4.281 9.245 3.36 49.41 .4140 3.09 5.767 9.379 2.91 52.51 .5156 3.40 7.182 9.371 2.60 55.26 .6172 3.61 8.598 9.407 2.39 57.67 .7569 3.80 10.544 9.367 2.20 58.70 .8712 3.92 12.136 , 9.246 2.08 59.73 1.0008 4.00 13.940 9.142 2.00 60.08 1.0617 4.03 14.789 9.083 1.97 60.08 1.1303 4.07 15.745 8.963‘ 1.93 60.77 1.2319 4.12 17.160 8.874 1.88 61.45 1.3411 4.18 18.681 8.762 1.82 61.97 1.4351 4.23 19.991 8.659 1.77 62.14 1.4681 4.25 20.450 8.618 1.75 5] and 83 equal the major and minor effective principal stresses, respectively. Failure taken at maximum deviator stress or at 20% axial strain. *Water content and dry density after consolidation. 259 The following tests were not carried up to assumed 20% strain. TABLE D.17 TRIAXIAL TEST DATA, SAMPLE CU-CF4 54% FIBER/46% KAOLINITE BY VOLUME Consolidation pressure = 1.50 kg/cm2 Angle between direction of compression and horizontal = 90° 01 = --- kg/cm2 A1, = --- f = --- 2 Water content = 64.82% G3f kg/cm Dry density = 41.18 pcf Uf = --- kg/sz TABLE 0.18 TRIAXIAL TEST DATA, SAMPLE CU-CF5 54% FIBER/46% KAOLINITE BY VOLUME Consolidation pressure = 3.00 kg/cm2 Angle between direction of compression and horizontal = 90° 01 = --- kg/cm2 Af = --- f - --- 2 Water content = 64.42% O3f ' kg/cm Dry density = 41.33 pcf u = --- kg/em2 260 The following tests were not carried up to assumed 20% strain TABLE 0.19 TRIAXIAL TEST DATA, SAMPLE CU-CF6 54% FIBERS/46% KAOLINITE BY VOLUME Consolidation pressure = 4.00 kgi/cm2 Angle 0’ = 0’ .1 between direction of compression and horizontal = 90° --- kg/cm2 Af = --- --- kg/cm2 Water content = 58.56% 2 Dry density = 43.59 pcf --- kg/cm TABLE 0.20 TRIAXIAL TEST DATA, SAMPLE CU-CF7 54% FIBERS/46% KAOLINITE BY VOLUME Consolidation pressure = 5. 00 kg/cm2 Angle 01 = G :1 between direction of compression and horizontal = 90° --- kg/cm2 . Af = --- --- kg/cm2 Water content = 58.11% Dry density = 43.78 pcf --- kg/cm2 261 TABLE 0.21 TRIAXIAL TEST DATA, SAMPLE CD;FC1 25% FIBER/75% KAOLINITE BY VOLUME Consolidation pressure = 4.00kg/cm2 Angle between direction of compression and horizontal = 90° o] = 10.806 kg/cm2 at 20% strain water content = 38.73% f Dry density = 75.69 pcf 03 = 4.00 kg/cm2 Volume after 3 f consolidation = 72.60cm Lgad Displacement gg1ume . Axial 61 53 a e ' (_g) (cm) 1cmg§ St{;;n (kg/cmz) (kg/cmz) 0.00 0.0000 0.00 0.000 4.000 4.00 7.42 .01778 .15 .236 4.771 4.00 11.71 .0483 .22 .639 5.213 4.00 16.28 .0914 .35 1.212 5.680 4.00 22.28 .1626 .56 2.154 6.284 4.00 27.00 .2286 .72 3.029 6.749 4.00 29.43 .2642 .81 3.499 6.986 4.00 33.44 .3175 .98 4.207 7.376 4.00 45.83 .4115 1.27 5.452 8.585 4.00 51.68 .5232 1.51 6.933 9.107 4.00 56.49 .6350 1.76 8.413 9.512 4.00 60.63 .7468 1.99 9.894 9.839 4.00, 62.34 .8001 2.10 10.600 9.967 4.00 64.75 .8890 2.27 11.778 10.130 4.00 67.51 .9982 2.45 13.226 10.303 4.00 69.91 1.0998 2.69 14.572 10.448 4.00 72.32 1.1913 2.89 15.783 10.594 4.00 74.04 1.2954 3.06 17.163 10.657 4.00 76.11 1.3963 3.22 18.50 10.748 4.00 78.17 1.5095 3.38 20.10 10.810 4.00 5] and 53 equal the major and minor effective principal stresses, respectively. Failure taken at maximum deviator stress or at 20% axial strain. *Water content and dry density after consolidation. 262 TABLE 0.22 TRIAXIAL TEST DATA, SAMPLE CD-FCZI 25% FIBER/75% KAOLINITE BY VOLUME Consolidation pressure = 2.50_kg/cm2 Angle between direction of compression and horizontal = 90° 0] = 7.782 kg/cm2 Water content = 42.44% f 2 Dry density = 73.47 pcf 03 = 2.500 kg/cm Volume after 3 f consolidation = 59.28cm %:a? Displacement Volume; Axial 5I 83 9 (cm) 1233?? 55:1" (kg/er) (kg/.621 0.00 0.0000 0.00 0.000 2.500 2.50 7.00 .0254 .06 .357 3.337 2.50 8.57 .0483 .10 .679 3.522 2.50 10 71 .0939 .25 1.322 ‘3.773 2.50 13.43 .1702 .50 2.394 4.086 2.50 17.00 .2819 .89 13.966 4.488 2.50 19 57 .3734 1.19 5.252 4.769 , 2.50 21.14 .4267 1.38 6.002 4.940- 2.50 23.85 .5334 1.70 7.503 5.224 2.50 25.86 .6147 1.97 8.647 5.431 2.50 28.71 .7366 2.31 10.362 5.712 2.50 30.85 .8306 2.60 11.684 5.918 2.50 32.71 .9144 2.84 12.863 6.091 2.50 34.00 .9754 3.00 13.720 6.206 2.50 36.00 1.0566 3.20‘ 14.864 6.386 2.50 37.28 1.1252 3.35 15.829 6.489 2.50 40.71 1.2268 3.59 17.258 6.801 2.50 47.24 1.3437 3.80 18.901 7.409 2.50 49.65 1.3894 3.90 19.545 7.628 2.50 51.37 1.4224 3.97 20.009 7.782 2.50 5] and 53 equal the major and minor effective principal stresses, respectively. Failure taken at maximum deviator stress or at 20% axial strain. *Water content and dry density after consolidation. 263 TABLE 0.23 TRIAXIAL TEST DATA, SAMPLE CD-FC3 25% FIBERS/75% KAOLINITE BY VOLUME Consolidation pressure = 1.50 _kg/cm2 Angle between direction of compression and horizontal - 90° 01 = 3.873 kg/cm2 Water content = 51.84% f Dry density = 66.39 pcf o = 1.50 kg/cmz Volume after 3 3f consolidation = 70.59cm Load Displacement Volume Axial 61 53 (kg) (cm) C122; ()1. 51123;" (kg/sz) (kg/c012) 0.00 ‘ 0.0000 0.00 0.000 1.500 1.50 2.17 0.0152 .01 0.208 1.725 1.50 4.74 0.0660 .18 0.900 1.989 1.50 6.31 0.1193 .34 1.628 2.148 1.50 7.60 0.1727 .51 2.355 2.277 1.50 9.74 0.2794 .90 .3.809 2.486 1.50 11.45 0.3785 1.25 5.159 2.648 1.50 13.31 0.4953 1.63 6.753 2.820. 1.50 14.74 0.5892 1.91 8.034 2.947 1.50 15.88 0.6807 2.20 9.281 3.045 1.50 17.74 0.8128 2.55 11.081 3.200 1.50 19.31 0.9271 2.90 12.639 3.328 1.50 20.88 1.0617 3.25 14.475 3.445 1.50 22.16 1.1557 3.45 15.756 3.539 1.50 23.31 1.2319 3.61 16.795 3.624 1.50 24.17 1.2877 3.76 17.557 3.687 1.50 25.03 1.3512 3.90 18.423 3.746 1.50 25.88 1.4122 4.05 19.254 3.803 1.50 26.31 1.4351 4.09 * 19.566 3.834 1.50 26.88 1.4681 4.12 20.01 3.873 1150 51 and 53 equal the major and minor effective principal stresses, respectively. Failure taken at maximum deviator stress or at 20% ax1al strain. *Water content and dry density after consolidation. Consolidation pressure Angle between direction of compression and horizontal = 90° 264 TABLE D.24 TRIAXIAL TEST DATA, SAMPLE CD-CF1 4.50 kg/cm2 54% FIBER/46% KAOLINITE BY VOLUME o] = 12.372 kg/cm2 water conten 48.96% 2 Dry density 3.06 pcf 03 = 4,50 kg/cm Volume after 3 consolidation 67.04 cm Load Displacement Volume Axial 5] 53 (kg) (cm) C122; ()9 , Sta; " (kg/cmz) (kg/cmz) 0.00 0.0000 0.00 0.000 4.500 4.50 5.86 .0127 .03 .177 5.128 4.50 10.29 . .0394 .10 .547 5.599 4.50 16.15 .1016 .31 1.412 6.216 4.50 18.43 .1321 .41 1.836 6.453 4.50 23.00 .2007 .69 2.789 6.924 4.50 25.86 .2464 .88 3.425 7.215 4.50 29.29 .3048 1.10 4.237 7.559 4.50 34.15 .3962 1.45 5.508 8.039 4.50 43.74 .4902 1.79 6.815 -8.993 4.50 51.65 .5817 2.10 8.086 9.758 4.50 55.43 .6731 2.42 9.357 10.093 4.50 58.53 .7442 2.65 10.346 10.362 4.507 61.28 .8179 2.89 11.369 10.590 4.50 64.72 .9042 3.18 12.570 10.874 4.50 70.22 1.0541 3.60 14.654 11.295 4.50 73.67 1.1379 3.85 15.818 11.559 4.50 77.45 1.2344 4.11 17.160 11.833 4.50 81.23 1.3335 4.39 18.538 12.098 4.50 85.36 1.4376 4.63 19.985 12.372 4.50 5] and 53 equal the major and minor effective principal stresses, respectively. axial strain. *water content and dry density after consolidation. Failure taken at maximum deviator stress or at 20% 265 TABLE D.25 TRIAXIAL TEST DATA, SAMPLE CD-CFZ 54% FIBER/46% KAOLINITE BY VOLUME Consolidation pressure = 3.50 kg/cm2 Angle between direction of compression and horizontal = 90° 01 = 10.060 kg/cm2 Water Content = 54.85% f 2 Dry density = 59.05 pcf 03 = 3.50 kg/cm Volume after 3 f consolidation = 70.98cm Load Displacement V01ume Axial 51 53 “‘91 “2"" C22; 3* “1:1" (kg/cmz) (kg/en?) 0.00 0.0000 0.00 0.000 3.500 3.50 5.57 .0152 .03 .203 4.088 3.50 9.71 .0457 .15 .609 4.523 3.05 14.00 .0965 .38 1.286 4.969 3.05 18.00 .1549 .60 2.064 5.381 3.50 22.86 .2388 .96 3.179 5.874 3.50 27.00 .3226 1.31 4.296 6.285 3.50 30.86 ‘.4064 1.65 5.413 6.662 3.50 34.86 .4978 2.00 6.631 7.043 3.50 41.23 .5893 2.32 7.848 7.655 3.50 51.90 .7391 2.86 9.844 8.658 3.50 54.99 .8433 3.19 11.231 8.907 3.50 59.12 .9829 3.51 13.092 9.218 3.50 61.87 1.0820 3.88 14.411 9.426 3.50 64.63 1.1760 4.10 15.663 9.620 3.50 66.35 1.2522 4.30 16.678 9.726 3.50 68.75 1.3462 4.51 17.929 9.874 3.50 70.47 1.4249 4.70 18.978 9.969 3.50 71.51 1.4605 4.79 19.452 10.035 3.50 72.19 1.5011 4 87_ 19.993 10.060 3.50 6] and 53 equal the major and minor effective principal stresses, respectively. Failure taken at maximum deviator stress or at 20% axial strain. *Water content and dry density after consolidation. 266 TABLE 0.26 TRIAXIAL TEST DATA, SAMPLE CD-CF3 54% FIBERS/46% KAOLINITE BY VOLUME Consolidation pressure = 2.50 kg/cm2 Angle between direction of compression and horizontal = 90° 01 = 8.126 kg/cm2 Water content = 56.77% f 2 Dry density = 59.24 pcf 03 = 2.50 kg/cm Volume after 3 f consolidation = 66.09 cm %oa? DispEac§ment Volume‘ éxial 5] 53 kg cm Chan e train 2 2 . .(Cm ) (z) (kg/cm ) (kg/cm ) 0.00* 0.0000 0.00 0.000 2.500 2.50 7.86 0.0228 .10 0.312 3.370 2.50 11.43 ’ 0.0812 .25 1.109 3.758 2.50 16.43 0.1879 .53 2.566 4.289 2.50 19.29~ 0.2616 .77 3.571 4.587 2.50 22.86 7 0.3632 1.08 4.958 4.948 2.50 26.72_ 0.4775 1.40 6.518 5.329 2.50 28.15' 0.5283 1.59 7.211 5.467 .2.50 31.58; 0.6273 1.90 8.563 5.796 2.50 33.86 0.7035 2.10 9.603 6.005 2.50 39.84 0.8280 . 2.50 11.302 6.572 2.50 46.03 0.9398 2.80 12.827 7.146 2.50 48.44 1.0210 3.20 13.937 7.357 2.50 49.47 1.0591 3.15 14.457 7.427 2.50 50.84 1.1277 3.30 15.393 7.519 2.50 52.56 1.1963 3.50 16.329 7.648 2.50 55.66 1.3030 3.75 17.785 7.879 2.50 57.72 1.3817 3.95 18.860 8.032 2.50 59.10 1.4478 4.12 19.761 8.107 2.50 59.44 1.4655 4.15 20.00 8.126 2.50 5] and 53 equal the major and minor effective principal stresses, respectively. Failure taken at maximum deviator stress or at 20% axial strain. *Water content and dry density after consolidation. 267- TABLE 0.27 TRIAXIAL TEST DATA, SAMPLE CD-F1 ALL FIBER Consolidation pressure = 1.50 kg/cm2 Angle between direction of compression and horizontal = 90° 01 = 5.032 kg/cm2 Water content = 144.57% f 2 “ Dry density = 29.09 pcf 03 = 1.500 kg/cm Volume after 3 f ” consolidation = 58.70cm %:a€ Dispzaciment Volume» Axial 6] 53 g cm Chan e , Strain 2 2 _ (cm )3 (,4) (kg/cm ) (kg/cm ) 0.00 0.0000 0.00 0.000 1.500 1.50 2.14 .0152 .10 .238 1.733 1.50 3.57 .0305 .21 .476 1.889 1.50 4.28 .0457 .34 .714 1.966 1.50 5.71 .0838 .62 1.309 2.121 1.50 .7.14 .1372 1.09 2.142 2.277 1.50 8.57 .2083 1.65 3.253 2.431 1.50 10.71 .3175 2.65 4.958 2.663 1.50 11.43 .3581 3.00 5.593 2.741 1.50 13.14 .4547 3.80 7.100 2.924 1.50 14.57 .5359 4.46 8.369 3.076 1.50 16.57 1.6375 5.30 9.956 3.289 1.50 18.28 .7188 6.00 11.226 3.472 1.50' 20.43 .8153 6.74 12.733 3.697 1.50 24.43 .9779 8.05 15.272 4.117 1.50 26.71 1.0592 8.60 16.541 4.349 1.50 29.28 1.1430 9.22 17.850 4.613 1.50 30.00 1.1709 9.42 . 18.286 4.685 1.50 32.86 1.2649 10.22 19.754 4.983 1.50 33.57 1.2878 10.40 20.112 5.055 1.50 6] and 53 equal the major and minor effective principal stresses, respectively. Failure taken at maximum deviator stress or at 20% axial strain. *Water content and dry density after consolidation. 268 TABLE 0.28 TRIAXIAL TEST DATA, SAMPLE CD-FZ _ALL FIBER Consolidation pressure = 3.00 kg/cm2 Angle between direction of compression and horizontal = 90° 01 = 10.858 kg/cm2 - Water content = 113.22% f 2 ' Dry density = 35.02 pcf 03 = 3.00 kg.cm . Volume after ‘ 3 f" ' consolidation = 61.16 cm %oa? Dispgac?ment Volume Axial 6] 53 kg cm Chan e Strain 2 2 _ _(cm ) A- (%) (kg/cm ) (kg/cm ) 0.00 0.0000 0.00 0.000 3.000 3.00 1.86. .0076 .10 .117 3.198 3.00 4.72 .0229 .14 .351 3.502 3.00 7.57 .0457 ,22 .702 3.803 3.00 10.43 .0813 ,40 1.248 4.104 3.00 14.72 .1600 ,35 2.457 4.550 3.00 17.57 .2235 1,22 3.432 4.843 3.00 20.57 .2870 1.58 4.407 5.149’ 3.00 23.72 .3607 1.95 5.538 5.464 3.00 26.14 .4166 2,25 6.397 5.705 3.00 29.00 .4877 2,52 7.488 5.984 3.00 31.86 .5512 2.97 8.464 6.264 3.00 35.00 .6223 3,30 9.556 6.563 3.00 46.53 .7645 4.10 11.740 7.687 3.00 54.10 .8357 4.38 12.832 8.408 3.00 60.98' .9728 5.20 14.939 9.036 3.00 63.39 1.0211 5.50 15.679 9.254 3.00 71.30 1.1506 5,35 17.669 9.975 3.00 77.15 1.2446 7,03 19.112 10.508 3.00 83.00 1.3386 7.98 20.55 11.075 3.00 5] and 53 equal the major and minor effective principal stresses, respectively. Failure taken at maximum deviator stress or at 20% aXTal strain. *Water content and dry density after consolidation. 269 TABLE D.29 TRIAXIAL TEST DATA, SAMPLE CD-F3 ALL FIBERS Consolidation pressure = 4.50 kg/cm2 Angle between direction of compression and horizontal = 90° 01 = 13.74 kg/cm2 ‘ *‘ Water content = 100.17% f 2 Dry density = 35.23 pcf 03 = 4.50 kg/cm 2 Volume after 3 f consolidation = 63.87cm Load Displacement Volumen‘ Axial 51 53 (kg) (cm) C?:; § ' St?2;n (kg/cmz) (kg/cm 0.00 0.0000 0.00 0.000 4 500 4.50 3,29 ,0102 .05 .161 4.824 4.50 10.43 ,0330 .10 .524 5.526 4.50 15.15 .0686 .2] 1.088 6.082 4.50 19,00 ,0991 .30 1.571 6.355 4.50 21.86 .1346 ,42 2.135 6.525 4.50 26.43 .2083 ,70 3.304 7.050 4.50 30.43 .2642 ,95 . 4.190 7-421 4.50 34.00 .3251 1,20 5.157 7.744 4.50 37.24 .3886 1,47 6.165 8.030 4.50 53.07 .5029 1.99 7.978 9.475 4.50 57.54 .5639 2,25 ‘ 8.945 9.859 4.50 64.76 .6807 2.80 ‘ 10.798 10.463 4.50 71.30 .7899 3,30 12.531 10.990 4.50 78.18 .8890 3.78 . 14.102 11.545 4.50 86.09 1.0008 4.34 , 15.875 12.169 4.50 91.94 1.0846 4 73 17.205 12.614 4.50 ' 18.857 13.275 4.50 100.54 1.1888 5.26 19.620 13.588 4.50 104.67 1.2369 5.51 1 96 4 50 108.79 1.2852 5.76 20.388 3.8 . 51 and 53 equal the major and minor effective principal stresses, respectively. Failure taken at maximum deviator stress or at 20% axial strain. *Water content and dry density after consolidation. 270 TABLE 0.30 TRIAXIAL TEST DATA, SAMPLE CD-F4 ALL FIBERS Consolidation pressure = 3.00 kg/cm2 Angle between direction of compression and horizontal = 90° o] = 9.123 kg/cm2 . water content = 118.81% f 2 ' Dry density = 31.36 pcf 03 = 3 kg/cm Volume after 3 f consolidation = 62.84cm Lgad Displacement Volume Axial 61 53 m an e . ' - ( g) (c ) ‘(cm ) 3 St?;;" (kg/cmz) (kg/cmz) 0.00 0.0000 0.00 - 0.000 3.000 3.00 4.86 .0178 .08 .289 3.474 3.00 7.86 .0483 .22 .785 3.765 3.00 9.86 .0889 .44 1.447 3.957 3.00 12.14 .1448 .75 2.356 4.173 3.00 15.72 .2362 --90 3.844 4.499 3.00 18.57 .2870 1.07 4.671 4.761 3.00 21.43 .3556 1.40 5.787 5.019 3.00 22.72 .3886 1.55 6.324 5.134 3.00 27.14 .4902 1.80 7.978 5.514 3.00 30.00 .5588 2.15 9.094 5.761 3.00 32.57 .6223 2.47 10.127 5.981 3.00 37.29 .7315 3.10 11.905 6.379 3.00‘ . 44.09 .8204 3.61 13.352 6.964 3.00 55.62 .9322 4.00 15.171 7.928 3.00 58.20 .9906 4.60 16.121 8.151 3.00 62.32 1.0643 5.02 17.320 8.476 3.00 65.08 1.1227 5.33 18.271 8.683 3.00 70.07 1.2141 5.85 19.759 9.063 3.00 72.99 1.2675 6.15 20.627 9.280 3.00 5] and 53 equal the major and minor effective principal stresses, respectively. Failure taken at maximum deviator stress or at 20% axial strain. *water content and dry density after consolidation. 271 TABLE 0.31 TRIAXIAL TEST DATA, SAMPLE CD-F5 22*. 2- ALL FIBERS Consolidation pressure = 4.50 kg/cm2 . Angle between direction of compression and horizontal = 90° 1 = 13.152 kg/cm2 Water content - 96.65%“ f 2 Dry density = 33.99 pcf 3 = 4.500 kg/cm ’ Volume after 3 f ' consolidation = 64.04 cm Load Displacement Volume . Axial 5] 53 “‘9’ ‘2") 52;}: 553,1" (kg/cm?) (kg/8.8) 0.00. 0.0000 0.00 0.000 4.500 4.50 5.57 .0203 .06 .336 5.024 4.50 8.57 .0432 .15 .715 5.305 4.50 11.57 .0787 .29 1.303 5.582 4.50 13.28 .1016 .40 1.682 5.739 4.50 16.28 .1448 .60 2.396 6.013 4.50 18.00 .1676 .73 2.774 6.170 4.50 21.71 .2261 1.01 3.741 6.503 4.50 26.28 .2997 1.40 4.960 6.909 4.50 31.00 .3734 1.85 6.179 7.326 4.50 36.25 .4470 2.24 7.398 7.782 4.50 51.73 .5461 2.81 9.038 9.143 4.50 59.64 .6680 3.50 11.056 9.794 4.50 66.17 .7391 3.98 12.233 10.342 4.50 71.33 .8229 4.36 13.620 10.738 4.50 75.81 .8839 4.69 14.629 11.088 4.50 83.37 .9855 5.24 16.311 11.669 4.50 90.25 1.0668 5.66 17.656 12.191 4.50 101.95 1.1938 6.34 19.758 13.066 4.50 104.01 1.2192 6.49 20.178 13.216 4.50 5] and 53 equal the major and minor effective principal stresses, respectively. Failure taken at maximum deviator stress or at 20% axial strain. *Water content and dry density after consolidation. 272 TABLE 0.32 TRIAXIAL TEST DATA, SAMPLE CD-F6 ALL FIBERS Consolidation pressure = 1.50 kg/cm2 Angle between direction of compression and horizontal = 90° 01 = 4.991 kg/cm2 at 2“, Water content = 150.22% f 2 Dry density = 27.69 pcf 03 = 1.50 kg/cm Volume after 3 f consolidation = 70.37cm Load Displacement Volume, Axial 5] 53 an e " - (kg) (cm) _(cm ) “85;" (kg/cmz) (kg/cmz) 0.00 0.0000 30.00 0.000 1.500 1.50 2.57 .0229 .20 .364 1.729 1.50 4.14 .0635 .58 1.011 1.869 1.50 6.43 .1498 1.40 2.387 2.071 1.50 7.43 *.1430 1.79 3.075 2.159 1.50 9.00 .2616 2.45 4.167 2.297 1.50 10.43 .3251 3.07 5.178 2.423 1.50 12.29 .4115 3.89 6.554 2.585 1.50 14.00 .4851 4.57 7.727 2.733 1.50 15.29 .5334 5.02 8.496 2.844 1.50 17.14 .6019 5.61 9.588 3.003 1.50 18.72 .6655 6.19 10.599 3.137 1.50 21.14 .7493 6.90 11.935 3.342 1.50” 23.72 .8306 7.60 13.229 3.559 1.50 27.14 .9398 8.55 14.968 3.844 1.50 30.72 1.0389 9.40 16.547 4.140 1.50 33.43- 1.1125 10.10 17.719 4.366 1.50 35.86 1.1709 10.60 18.650 4.565 1.50 39.22 1.2344 11.18 19.662 4.843 1.50 44.04 1.2827 11.57 20.430 5.242 1.50 5] and 53 equal the major and minor effective principal stresses, respectively. Failure taken at maximum deviator stress or at 20% axial strain. *Water content and dry density after consolidation. 273 TABLE 0.33 TRIAXIAL TEST DATA, SAMPLE CU-Fl _ALL FIBERS Consolidation pressure = 2.50 kg/cm2 Angle between direction of compression and horizontal = 90° 01. 5 4.950 kg/cmz at 15 1/2 % strain Water content = 143.29% f 2 Dry density = 28.88 pcf o3f = 0.0 kg cm at 15 1/2 % strain 1:31 Displacsment Pore Axial 5] 53 cm Pressu e St ' .9 (kg/cmg) 7:1" .(kQ/sz) (kg/cmz) 0.00 0.0000 0.00 0.000 2.500 2.50 6.29 .0330 .10 .514 2.989 2.40 8.43 .0559 .15 .869 3.138 2.35 9.86 .0813 .24 1.265 3.178 2.26 11.29 .1041 .32 1.621 3.227 2.18 12.71 .1295 .42 2.016 3.254 2.08 14.14 .1549 .50 2.412 3.301 2.00 16.28 .1956 .63 3.044 3.358 1.87 19.14 ' .2489 .94 3.874 3.295 .1.56 22.00 .3048 1.04 4.744 3.436 1.46 24.86 .3632 1.24 5.654 3.470 1.26 29.43 .4749 1.59 7.393 3.479 .91 32.71 .5563 1.85 8.658 3.466 .65‘ 39.79 .7289 2.20 11.347 3.626 .30 48.39 .8382 2.38 13.047 4.087 .12 54.24 .9195 2.45 14.312 4.431 .05 56.99 1.0008 2.50 15.577 4.536 0.00 59.05 1.0566 2.50 16.447 4.652 0.00 62.04 1.1557 2.51 17.989 4.786 -.01 64.56 1.1989 2.51 18.661 4.950 -.01 5] and 53 equal the major and minor effective principal stresses, respectively. Failure taken at maximum deviator stress or at 20% ax1al strain. *Water content and dry density after consolidation. 274 TABLE 0.34 TRIAXIAL TEST DATA, SAMPLE CU-F2 ALL FIBERS Consolidation pressure = 0.50kg/cm2 Angle between direction of compression and horizontal = 90° o] = 1 126 kg/cm2 A1. = 0.20 f = 2 Water content = 246.88% O3f 0'34 kg/cmz Dry density = 19.10 pcf Uf = 0.16 kg/cm soa? Displacsment Pore Axial 6] 53 kg cm Pressure Strain 2 2 (kg/cmz) (%) (kg/cm ) (kg/cm ) 0.00 0.0000 0.00 0.00 0.500 0.50 3.00 .0831 .05 1.08 .648 .45 5.30 .1956 .10 2.55 .745 .40 6.80 .2883 .13 3.76 .807 .37 7.90 .4473 .14 5.84 .858 .36 8.90 .5743 ' .14 7.49 .911 .36 9.50 .7061 '.14 9.22 ..937 .36 10.00 .8529 .15 11.13 .944 .35 11.40 .9896 .15 12.92 1.014 .35 12.10 1.1094 .15 14.48 1.042 .35 12.90 1.2842 .15 16.76. 1.068 .35 13.80 1.4089 .15 18.39 1.103 .35 14.70 1.5336 .16 20.02 1.126 .34 15.90 1.6584 ' .16 21.65 1.173 .34 51 and 53 equal the major and minor effective principal stresses, respectively. Failure taken at maximum deviator stress or at 20% axial strain. *Water content and dry density after consolidation. 275 TABLE 0.35 TRIAXIAL TEST DATA, SAMPLE CU-F3 ALL FIBERS Consolidation pressure = 0.50 kg/cm2 Angle between direction of compression and horizontal = 90° 011: = .773 kg/cm2 Uf = :.50 kg/cm2 = 2 A = 0.65 O3f 0'00 kg/cm wgter content = 299.61% Dry density = 16.90 pcf 1fia1 Displacsment Pore Axial 5] g cm Pressu e Strai 0.00 0.0000 0.00 0.00 0.500 0. 3.00 0.1194 0.24 1.51 0.436 0. 5.00 .2032 0.36 2.57 0.430 0. 6.30 .2896 0.44 3.67 0.421 0. 7.00 .4039 0.48 5.12 0.416 0. 8.70 .5410 0.50 6.85 0.483 0. 9.60 .6731 0.50 8.53 0.523 0. 10.50 .8433 0.50 10.68 0.559 0. 11.60 .9855 0.50 12.48 0.605 O. 12.70 1.1481 0.50 14.54 0.646 0. 14.00 1.3132 0.50 16.64 0.695 0. 15.10 1.4453 0.50 18.31 0.735 0. 15.70 1.5240 0.50 19.31 0.755 0. 16.90 1.6485 0.50 20.88 0.796 0. 61 and 53 equal the major and minor effective principal stresses, respectively. Failure taken at maximum deviator stress or at 20% axial strain. *Water content and dry density after consolidation. 276 TABLE 0.36 TRIAXIAL TEST DATA, SAMPLE CU-F4, ALL FIBERS Consolidation pressure = 3.50 kg/cm2 Angle between direction of compression and horizontal = 90° oi = 4.738 kg/cm2 Af = 0.72 kg/cm2 o3f = .39 kg/cm2 Water content = 158.53% f Dry density = 30.15 pcf uf = 3.11 kg/cm2 1031 Dispzacsment Pore Axial 01 53 kg cm Pressure Strain 2 2 (kg/cm?) (%) (kg/cm ) (kg/cm 1 0.00 0.0000 0.00 0.00 '3.500 3.50 4.15 .0625 0.00 .88 3.793 3.50 15.25 .2035 .27 2.87 4.283 3.23 21.45 .3914 .53 5.52 4.413 2.97 29.20 .5088 .84 7.18 4.590 2.66 36.60 .6495 1.20 9.16 4.668 2.30 43.30 .7747 1.54 10.93 4.707 1.96 49.30 .8687 1.90 12.26 4.681 1.60 55.30 .9939 2.20 14.02 4.686 13.0 60.50 1.0879 2.50 15.35 4.647 1.00 65.50 1.1816 2.71 16.67 4.677 .79 69.20 1.2756 2.90 18.00 4.641 .60 73.20 1.3304 3.02 18.77 4.715 .48 76.30 1.4166 3.11 19.99 4.738 .39 77.60 1.4478 3.15 20.43 4.748 .35 5] and 53 equal the major and minor effective principal stresses, respectively. Failure taken at maximum deviator stress or at 20% axial strain. *Water content and dry density after consolidation. 277 TABLE 0.37 TRIAXIAL TEST DATA, SAMPLE CU-F5, ALL FIBERS Consolidation pressure= 1.0 kg/cmz Angle between direction of compression and horizontal = 90° 01 = 1.715 kg/cm2 Af = .58 f o _ 2 Water content = 234.4% 3f ‘ 0'0 kg/sz Dry density = 20.86 pcf Uf = 1.00 kg/cm Load Displacement Pore Axial 51 53 (kg) (cm) P2375558 Stfgsn (kg/cmz) (kg/cmz) 0.00 0.0000 0.00 0.00 0.000 0.00 1.60 .0127 .12 .16 .976 .88 7.80 .0973 .39 1.25 1.071 .61 12.80 .2113 .63 2.70 1.116 .37 15.90 .3297 .80 4.22 1.112 .20 17.80 .4226 .91 5.41 1.098 .09 19.00 .5072 .92 6.50 1.144 .08 21.00 .5958 .96 7.63 1.201 .04 22.20 .7102 .98 9.10 1.228 .02 23.90 .8242 .99 10 56 1.290 .01 25.50 .9721 1.00 12.46 1.336 0.00 27.00 1.0990 1.00 14.08 1.388 0.00 29.40 1.2088 1.00 15.49 1.488 0.00‘ 32.00 1.3526 1.00 17.33 1.584 0.00 34.00 1.4752 1.00 18.91 1.651 0.00 36.90 1.6104 1.00 20.64 1.753 0.00 51 and 53 equal the major and minor effective principal stresses, respectively. Failure taken at maximum deviator stress or at 20% axial strain. *Water content and dry density after consolidation. 278 TABLE 0. 38 TRIAXIAL TEST DATA, SAMPLE CU- F6, ALL FIBERS Consolidation pressure = 1. 00 kg/cmz Angle between direction of compression and horizontal = 90° o] = 1.340 kg/cm2 A1. = .75 f o - 2 Water content = a.% 3f ' 0‘0 kg/sz Dry density = n. fpcf uf = 1.00 kg/cm 10a? Dispzacsment Pore Axial 6] 03 kg cm Pressu e Strain 2 2 . “kg/cmfi (z) (kg/cm ) (kg/cm ) 0.00 0.0000 0.00 0.00 1.000 1.00 5.00 .0257 .07 .32 1.267 .93 7.10 .0686 .24 .87 1.236 .76 8.20 .1407 .39 1.79 1.154 .61 9.10 .2057 .49 2.61 1.109 .51 10.10 .2400 .58 3.05 1.082 .42 11.50 .3053 .66 3.88 1.087 .34 12.04 .3635 .72 4.62 1.079 .28 13.00 .4219 .75 5.37 1.081 .25 13.20 .4800 .80 6.11 1.038 .20 14.00 .4973 .86 6.33 1.026 .14 15.00 .5898 .87 7.53 1.067 .13 16.00 .6515 .87 8.29 1.122 .13~ 16.20 .7236 .88 9.21 1.114 .12 16.80 .7922 .92 10.08 1.101 .08 18.80 .9294 .95 11.82 1.170 .05 20.00 1.0668 .98 13.57 1.188 .02 21.20 1.2586 1.00 16.02 1.203 0.00 22.80 1.3716 1. 00 17.45 1.272 0.00 24.80 _ 1.5773 1. 00 20.07 1.340 0.00 51 and 53 equal the major and minor effective principal stresses, respectively. Failure taken at maximum deviator stress or at 20% axial strain. *Water content and dry density after consolidation. 279 TABLE 0.39 TRIAXIAL TEST DATA, SAMPLE CU-F7 ALL FIBERS ’ Consolidation pressure =2.03 kg/cm2 Angle between direction of compression and horizontal = 90° o] = 4.032 kg/cm2 Af = 0.50 03f = .02 kg/cm2 Water content = 169.81% f 2 Initial dry density = 29.70 pcf U1c = 2.01 kg/cm ' ssa? Displacsment Pore Axial 51 53 g cm Pressure Strain 2 2 (kg/cmZ) (%) (kg/cm ) (kg/cm ) 0.00 0.0000 0.00 0.000 2.03 2.03 2.87 0.0813 0.00 .05 2.459 2.03 4.30 0.0914 0.02 .024 2.652 2.01 6.45 0.1168 0.08 .73 2.906 1.95 8.60 0.1524 0.12 1.42 3.179 1.91 10.03 0.1626 0.19 1.61 3.317 1.84 11.46 0.1727 0.25 1.81 3.465 1.78 13.61 0.1930 0.43 2.20 3.593 1.60 15.05 0.2159 0.58 2.64 3.644 1.45 17.20 0.2565 0.80 3.42 3.717 1.23 19.35 0.3175 1.02 4.60 3.773 1.01 21.50 0.3988 1.25 6.16 3.800 0.78 24.36 0.5613 1.58 9.30 3.758 0.45 25.79 0.6579 1.71 11.15 3.750 0.32 27.23 0.7518 1.82 12.96 3.758 0.21 28.66 0.8484 1.90 14.82 3.785 0.13 30.09 0.9296 1.94 16.39 3.856 0.09 31.53 1.0135 1.99 18.00 3.910 0.04 32.96 1.0897 2.01 19.47 3.993 0.02 34.39 1.1582 2.02 20.79 4.089 0.01 Bl'and 63 equal the major and minor effective principal stresses, respectively. Failure tkane at maximum deviator stress or at 20% axial strain. *water content and dry density after consolidation- “'111111111111111111111111111115