DYNAMIC STRESS TRANSDUCERS AND THE USE OF CONTINUUM MECHANICS IN THE STUDY OF VARIOUS SOIL STRESS-STRAIN RELATIONSHIPS TIIcsls Ior II“: Degree oI DI’I. D. MICHIGAN STATE UNIVERSITY Wesley Lamar Harris 1960 This is to certify that the thesis entitled Dynamic Stress Transducers and the Use of Continuum Mechanics in the Study of Various Soil Stress-Strain Relationships presented bg Wesley Lamar Harris has been accepted towards fulfillment of the requirements for Ph.D degree inAggicultux-al Engineering MKM fliajor professor Date OCtOber 28 l 60 0469 —""'1‘7.‘t , ,7fliiw, VJ LIBRARY Michigan State University er .. (a. a DYNAMIC STRESS TRANSDUCERS AND THE USE OF CONTINUUM MECHANICS IN THE STUDY OF VARIOUS SOIL STRESS-STRAIN RELATIONSHIPS by Wesley Lamar Harris AN ABSTRACT Submitted to the School for Advanced Graduate Studies of Michigan State University of Agriculture and Applied Science in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Department of Agricultural Engineering 1960 Na/ I ”PM“ “M f:/ f}:- fieM 94} fl’fr f/y- («4 ABSTRACT The changes in soil consolidation resulting from externally applied forces and the effect of these changes on the physical properties of the soil have been studied by many individuals. The results of one of the investi- gations revealed that the concept of continuum mechanics could be used as a mathematical model for studying the soil compaction problem. The development of soil stress- strain relationships which will permit the prediction of the changes in the state of compaction caused by various implements and power units will be a major contribution toward controlling soil compaction. . The concept of continuum mechanics was used to determine various stress-strain relationships. A Six Directional Stress Transducer capable of measuring sufficient data to determine the components of the general stress tensor was developed and compared with the method used by vanden Berg (1958). A W Cell capable of measuring mean stress directly was developed and the values of mean stress calculated from the Type A and 6 DST data were compared. The data from a series of 27 tests of 5 replications composed of three depths below the loading surface, three moisture contents and three rates of loading are presented. 11 The data was analyzed using MISTIC, an electronic digital computer, to determine the relationships between the invariants of the stress tensor and bulk density. The hypothesis that changes in mean normal stress, an invariant of the stress tensor, are related to changes in volumetric strain was tested by measuring the stress tensor and bulk density in the soil while the soil was subjected to dynamic loads of various magnitudes. Based on the data presented, the hypothesis could not be accepted or rejected. The data indicated that of the four invariants of the stress tensor investigated the maximum shear stress related best to changes in bulk density. The relationships between the invariants and bulk density were affected by the moisture content at the higher rate of loading and deeper depths. The rates of loading data was varied; therefore the effects on the relationships could not be determined. The values of mean stress obtained directly from the W Cell compared best with the values calculated from the Type A data. Comparison of the two methods of measuring vertical stress with theoretical values determined with Froehlick's equation showed good agreement with the Type A values at the two deeper depths. Fbr the 5-inch depth, both the 6 DST and Type A data were greater than the theoretical data for a given surface load. iii The relationships between the invariants and bulk density are exponential for the soil studied. The relationship between mean stress and applied load appears to be linear for loads greater than 5 pounds per square inch. iv DYNAMIC STRESS TRANSDUCERS AND THE USE OF CONTINUUM MECHANICS IN THE STUDY OF VARIOUS SOIL STRESS—STRAIN RELATIONSHIPS by Wesley Lamar Harris A THESIS Submitted to the School for Advanced Graduate Studies of Michigan State University of Agriculture and Applied Science in partial fulfillment 6f the requirements for the degree of DOCTOR OP PRILO SOPHY Department of Agricultural Engineering 1960 6/5723? e/zo/w VITA Wesley Lamar Harris candidate for the degree of Doctor of Philosophy Final examination: October 28, 1960; 2:00 P.M.; Room 218 Agricultural Engineering Building Dissertation: Dynamic Stress Transducers and the Use of Continuum Mbchanics in the Study of variousLStress—Strain Relationships Outline of Studies: major subject: Agricultural Engineering Minor subjects: Applied Mechanics mathematics Biographical items: Born: November 12, 1931; Taylorsville, Georgia Undergraduate studies: University of Georgia BOSOAOE.’ 1953 University of Georgia M.S., 195 , Michigan State University 1958-1960 Gratuate Studies: Experience: 1953-1956 Commissioned Officer, Corps of Engineers, Uhited States Army 1956-1958 Instructor, University of Georgia 1958-1960 Graduate Assistant, Michigan State University Professional and Honorary Affiliations American Society of Agricultural Engineers Registered Land Surveyor Sigma XI, Alpha Zeta, Sphinx, Blue Key, Omicron Delta Kappa, Aghon ACKNOWLEDGEMENTS In the course of planning and conducting an investi- ation of the nature presented in this thesis, the cooperation and advice of numerous individuals is necessary. The author wishes to express his sincere appreciation to all those people who contributed to make this thesis possible. A special note of thanks is extended to those individuals mentioned below. Dr. Arthur W. Farrall, Head, Department of Agricultural Engineering, Michigan State University, provided the financial assistance for the pursuance of the program of study. Dr. wesley F. Buchele, the author's major professor provided valuable assistance, encouragement, guidance, and inspiration throughout the author's course of study. The guidance committee, Prof H. F. McColly and Dr. Carl Hall, Agricultural Engineering, Dr. L. E. Malvern, Applied Mechanics, Dr. E. A. Nordhaus, Mathematics, and Dr. A. E. Erickson, Soil Science Departments, provided constructive criticisms and suggestions during the course of study and Preparation of this manuscript. Col. M. G. Bekker of the Land Locomotion Laboratory and Mr. Alexander Brede of the Motor Wheel Corporation arranged for the loan of strain gage equipment from their repective organizations. vii Dr. Clement A Tatro of the Applied Mechanics Department and Dr. T. H. wu of the Civil Engineering Department, Michigan State university loaned electronic equipment used during the experimental tests. In addition Dr. Tatro gave valuable assistance during the construction and calibration of the strain gage transducers. . Jim Cawood and Mr. Glenn Shiffer of the Agricultural If” AHA Engineering Department gave valuable aid in the construction of the equipment. Mr. Cawood demonstrated expert workman— ship during the construction of the six directional stress transducer. Mr. Sniffer was a source of many challenges which were stimulating and educational. Mr. Jack V. Stong, Graduate Student and Mr. George Keller, undergraduate Student, Agricultural Engineering, assisted in the construction of the soil handling equipment. Mr. Harold Brockbank of the Agricultural Engineering Department, and Mr. John Morrison, undergraduate Student, Agricultural Engineering, assisted during the investigation. The author is especially grateful to his wife, Libby for her encouragement and help which made the completion of this report possible. To his elder son, Wes for his confidence in his father's ability and his younger son, Jamie, who didn't appreciate the time his father spent studying. viii TABLE OF CONTENTS Section INTRODUCTION . . . . . . . . . REVIEW OF LITERATURE . . . . . THEORY . . . . . . . . . . . . APPARATUS AND INSTRUMENTATION Design and development of Stress Transducer . . . w cell 0 O O O O O O I 0 Soil handling equipment . Force transducer . . . . PRWEDURE O O O O O O O O O 0 O O O 0 RESULTS AND DISCUSSION . . . . . . . . Relationship between mean normal stress and bulk density . . . Relationship between second invariant and bukdenSityocooeooooooc Relationship between maximum normal stress and bulk density . . . . Relationship between maximum shear stress and bulk density . . . The effect of moisture content on the relationship between mean normal stress andbulkdensitycoooooeoooo The effect of moisture content on the relationship between second invariant and b11115 density 0 o c The effect of moisture content on the relationship between maximum normal stress and bulk density . . . . . . . . ix Page 0 O O 0 O O O O 1 O O O O O O O O 4 O O O O O 0 O O 12 o} o o o 20 Six Directional- . O O O O O O O O O O 20 o o o c e c e o 34 O O O O O O O O 34 O O O O 0 O I O 38 O O O O O O O 43 O O O O O O I O 49 O O O O O O O O 53 c c o o o 58 e c c e o o o o c e o 65 o c I c c o o o 72 O o o o 78 O O O O 83 o o o g 87 Section Page The effect of moisture content on the relationship between maximum shear stress c.0091 andbulkdenSj-tyooooeooeooo The effect of rate of loading on the relationship between mean normal stress and bulk density . . . . . . . . . . . . . . . 91 The effect of rate of loading on the relationship between second invariant andbUlkdeHSityoeoccooooeooooo99 The effect of rate of loading on the ' relationship between maximum normal . 99 stress and bulk density . . . . . . . . . . . The effect of rate of loading on the relationship between shear stress and bulk denSity O O O O O O O O O O 0 O O 0 0 Comparison of three methods used to determine mean normal stress . . . . . . 106 O O O 106 The effect of rate of loading on the relationship between mean stress and applied load . . . . . . . . . . . . . . . . . 118 The effect of moisture content on the relationship between mean normal Stress and applied load 0 O O O O O O O O O O O 123 o o o o o o o e 136 o o o o o 138 142 CONCLUSIONS 0 O O O O O O O O O O O 0 REFERENCES 0 O O O O O O 0 O O O O O O O O 0 APPENDIX 0 O O O O O O O O O C Figure 1. 9. 10. 11. 12. 13. LIST OF FIGURES Detail drawing of the four directional stress transducer . . . . . . . . . . . . . Drawing of the six directional stress transducer showing the location of diaphragm pressure cells . . . . . . . . . Calibration curve for Redshaw strain gage on 0.010 inch thick diaphragm 3/4 inch in diameter 0 O O O O O O O O O O O O O O 0 Calibration curve for Redshaw strain gage mounted on 0.020 inch thick diaphragm 3/4 inch in diameter . . . . . . . . . . . A typical calibration curve using bridge arrangement as shown. One complete Redshaw 2-ED type strain gage used as sensing element and the other as dummy gageSeeeoocccoocococoooo A view of the six directional stress tranSduCer O O O O O O O O O O 0 O O O O 0 Calibration device used to obtain calibration dataforthGGDST............. The W Cell that was used to measure mean StreSSdireCtly 0000000000... A view of the soil handling equipment . . . . Detail drawing of the W Cell used to measure mean Stress direCtly o o o o c c o o o o 0 Calibration curve for W Cell showing number of lines deflection versus applied load . . A view of the loading plate, force transducer and hydrau1ic cylinder 0 o o o o e o o o o A view of the pressure transducers and balloons used to obtain data: . . . . . . . xi Page Figure Page 14. Detail drawing of force transducer showing location of strain gages and ball and socket Joint . . . . . . . . . . . . . . . . . 41 15. Calibration curve for force transducer showing number of lines deflection versus applied load . . . . . . . . . . . . . . 42 16. mean normal stress versus bulk density for data obtained with 6 Directional Stress Transducer . . . . . . . . . . . . . . . 59 17. mean normal stress versus bulk density for data obtained with Type A pressure cells . 60 18. Second invariant of stress deviator tensor versus bulk density for data Obtained with 6 Directional Stress Transducer . . . . . 66 19. Second invariant of stress deviator tensor versus bulk density for data obtained with Type A pressure cells . . . . . . . . . . 67 20. Comparison of the values of the second invariant calculated from the Type A and 6 DST data 0 O O O O O O O O O O O O O O I 68 21. maximum normal stress versus bulk density for data obtained with 6 Directional Stress Transducer . . . . . . . . . . . . . . . 73 22. maximum normal stress versus bulk density for data obtained with Type A pressure cells . 74 23. Maximum shearing stress versus bulk density for data obtained with 6 Directional Stress TranSducer o o o o e o o e o o o o o c o 79 24. maximum shearing stress versus bulk density for data obtained with Type A pressure cells . 80 25. The effect of moisture content on the relationship between mean stress and bulk density. Data Obtained with 6 DST . . . 84 26. The effect of moisture content on the relationship between mean stress and bulk density. Data obtained with Type A Pressure C3118 o o o c o o o o o c o c o o o o 85 xii“ Figure 27. The effect of moisture content on the relationship between the second invariant and bulk density. Data obtained with 6 DST . . 88 Page 28. The effect of moisture content on the relationship between the second invariant and bulk density. Data obtained with Type A pressure cells . . . . . . . . . . . . . 89 29. The effect of moisture content on the relationship between the maximum normal stress and bulk density. Data obtained with5DST.e...............o92 30. The effect of moisture content on the relationship between the maximum normal stress and bulk density. Data obtained with Type A pressure cells . . . . . . . . . . 93 31. The effect of moisture content on the relationship between the maximum shear stress and bulk denstiy. Data obtained '1th6DSTocccoooocoeooecoeogs 32. The effect of moisture content on the relationship between maximum shear stress and bulk density. Data obtained with Type A pressure cells . . . . . . . . . . . . . 96 33. The effect of rate of loading on the relationship between.mean stress and bulk density. Data obtained with 6 DST . . . 100 34. The effect of rate of loading on the relationship between mean stress and bulk density. Data obtained with Type A pressure cells . . . . . . . . . . . . 101 35. The effect of rate of loading on the relationship between the second invariant and bulk density. Data obtained with 6 DST . 103 36. The effect of rate of loading on the relationship between the second invariant and bulk density. Data Obtained with TYPEAPresmecellsoocooooeooo.104 xiii Figure Page 37. The effect of rate of loading on the relationship between the maximum normal stress and bulk density. Data obtained with 6 DST . . . . . . . . . . . 107 38. The effect of rate of loading on the relationship between the maxrmwm normal stress and bulk density. Data obtained with Type A pressure cells . . . 108 39. The effect of rate of loading on the relationship between the maximum shear stress and bulk density. Data Obtained With 6 DST O O O O O O O O O O O O O 110 40. The effect of rate of loading on the relationship between the maximum shear stress and bulk density. Data obtained with Type A pressure cells . . . . . . . . . . 111 41. Comparison of the regression lines for the three methods used to determine mean stress. Data obtained at the 5-inch depth, 1.00 in/sec rate of loading and a moisture content0f17e41%cocoa-00000000113 42. Comparison of the regression lines for the three methods used to determine mean stress. Data obtained at the 5-inch depth, 1.00 in/sec rate of loading and a moisture content0f10079%000000.0000000114 43. Comparison of the regression lines for the three methods used to determine mean stress. Data obtained at the 10-inch depth, 1.00 in/sec rate of loading and a moisture content of 17.41 % . . . . . . . . . . . . . . 115 44. Comparison of the regression lines for the three methods used to determine mean stress. Data obtained at the 10-inch depth, 1.00 in/sec rate of loading and a moisture content0f10095%oooocooocecoo.116 45. Comparison of the regression lines for the three methods used to determine mean stress. Data obtained at the 15-inch depth, 1.00 in/sec rate of loading and a moisture content of 12.31% . . . . . . . . . . . . . . 117 xiv Figure Page 46. The effect of rate of loading on the relationship between mean stress and applied load at 5-inch depth. Data obtained with 6 DST at a moisture content ranging from 8.89 to 10.79% . . . . . 119 47. The effect of rate of loading on the relationship between mean stress and applied load at 5-inch depth. Data obtained with Type A pressure cells at a moisture content ranging from 8.89 to 10.79% 120 48. The effect of rate of loading on the relationship between mean stress and applied load at 5-inch depth. Data obtained with 6 DST at a moisture content ranging . from16905 t017067% o c c o o o o c o o c c 0121 49. The effect of rate of loading on the relationship between mean stress and applied load at S-inch depth. Data obtained with Type A cells at a moisture content ranging from 16.05 to 17.67% . . . . . 122 50. The effect of moisture content on the relationship between mean stress and applied load at S-inch depth and 0.38 in/sec rate of loading. Data obtained with 6 DST . . 124 51. The effect of moisture content on the relationship between mean stress and applied load at S-inch depth and 0.38 in/sec rate of loading. Data obtained with Type A cells . . . . . . . . . . 125 52. The effect of moisture content on the relationship between mean stress and applied load at 15-inch depth and 0.62 in/sec rate of loading. Data obtained with 6 DST . . . . . . . . . . . . . 126 53. The effect of moisture content on the relationship between mean stress and applied load at 15-inch depth and 0.62 in/sec rate of loading. Data obtained with TypeApressurecells ............127 IV Figure Page 54. The effect of moisture content on the relationship between mean stress and applied load at 10-inch depth and 1.00 in/sec rate of loading. Data obtained with 6 DST . . . . . . . . . . . . . 129 55. The effect of moisture content on the relationship between mean stress and applied load at 10-inch depth and 1.00 in/sec rate of loading. Data obtained with Type A cells . . . . . . . . . . 130 56. Comparison of the two instruments used to measure the vertical stress with theoretical values at a depth of 5 inches below the loading surface. Measured data obtained from test 17 . . . . . . . . . . . . 132 57. Comparison of the two instruments used to measure the vertical stress with theoretical values at a depth of 10 inches below the loading surface. measured data obtained from Test 16 . . . . . . . . . . . . 133 58. Comparison of the two instruments used to measure the vertical stress with theoretical values at a depth of 15 inches below the loading surface. Measured data obtained from test 15 . . . . . . . . . . . . 134 xvi LIST OF TABLES Table Page 1. Average output of number one set of gages in DST calibrated for one line ' deflection equal to one psi . . . . . . . . . . 31 2. Physical description of the Brookston soil needintest00000000000000.0046 3. Changes in bulk density produced by the weight of the soil as determined with the volumetric transducer . . . . . . . . . . . 47 4. Description of the laboratory tests . . . . . . . 50 5. Statistical analysis for mean normal stress versus bulk density . . . . . . . . . . . . . . 54 6. Comparison of regression coefficients of the r m versus bulk density relation for different stress states and same stress state for the two methods used to Obtain data 0 O 0 O O O O O O O O O O O 0 g 57 7. Statistical analysis for second invariant verS'quulkdenSj-tycoo0000000000062 8. Comparison of regression coefficients of the II versus bulk density relation for diffegent stress states and same stress state for the two methods used tOObtamdataocoocoeeoeeeoo..64 9. Statistical analysis for maximum normal stress versus bulk density . . . . . . . . . . 69 10. Comparison of regression coefficients of the WI versus bulk density relation for different stress states and same stress state for the two methods used to obtain data...ooooeoeoooceoceooo71 11. Statistical analysis for maximum shear stress versus bulk density . . . . . . . . . , 75 xvii Table Page 12. Comparison of regression coefficients for 'X max versus bulk density relations for different stress states and same stress state for the two methods used to Obtain data 0 O O O O O O O O O O O O O 0 O 77 13. Comparison of regression coefficients of the 0" m versus bulk density relations at different moisture contents and between methods for a given test . . . . . 82 14. Comparison of regression coefficients of the II versus bulk density relations at constafit depth and different moisture contents and between methods for a given test. 86 15. Comparison of regression coefficients of the GI versus bulk density relations at constant rate, constant depth, and different moisture contents and between methods for a given test . . . . .‘. . . . . . 9O 16. Comparison of regression coefficients of the’rmax versus bulk density relations at constant rate, constant depth and different moisture contents and between methods for a given teSt O O O O O O O O O O O O O O O O O 94 17. Comparison of regression coefficients of the Em versus bulk density relations at different rates of loading and between methOds for a given test 0 c o e o o o o o o o 97 18. Comparison of regression coefficients of the II versus bulk density relations at differgnt rates of loading and between methods for a given test . . . . . . . . . . . 102 19. Comparison of regression coefficients of ' the 01 versus bulk density relations at different rates of loading and between 105 methods for a given test . . . . . . . . . . . 20. Compar son of regression coefficients of the max versus bulk density relations at different rates of loading and between 109 methods for a given test . . . . . . . . . . . xviii Table Page 21. Comparison of the regression coefficients calculated for the relationship between mean normal stress and applied load for a constant rate of loading of 1.00 inch Per second 0 O O 0 O O O O O O O O O O O O O O 1 12 A Calculated values of mean normal stress, second invariant of deviator stress tensor, maximum and minimum principal stresses, and maximum shear stress for the Type A Cells and Six Directional Stress Transducer. . . . . 143 xix INTRODUCTION A major factor in the advancement of civilization during the twentieth century has been the mechanization of agriculture. The extensive use of larger power units and associated equipment has benefited mankind, but it has been a source of problems too; 1.3. inadequate soil air movement, reduced infiltration and percolation rates, mechanical impedance to roots and reduced crop yields are caused to some degree by excessive compaction. The complete solution of these problems will require the combined efforts of many branches of science. Soil compaction resulting from large externally applied forces has been studied by agricultural engineers and soil physicists. Unfortunately their results to date have not produced an adequate agricultural soil mechanics. Although soil is one of the oldest materials used by man, accurate stress-strain relationships for all soil conditions and types of loading have not been developed. The main reason that this is true is that agricultural soils vary in density and texture and are non-homogeneous and inelastic. Vanden Berg(1960) stated that there is no analytical method for developing a rigorous stress- strain relationship. The stress and strain developed in a soil mass must be measured simultaneously and stress- strain relationships for soil determined empirically. The study of soil compaction consists of two phases. The first phase involves determining the distribution of stresses in a soil mass caused by externally applied forces. The second phase involves determining the effect that these stresses or strains have on the soil mass. Since one of the effects of the stresses developed is to force a modification of the stress pattern, the two phases must be studied simultaneously. In general the stress distribution developed by an externally applied load will depend upon several factors that include the following: 1. The magnitude and type of load 2. The size and shape of the contact area where the force is applied 3. The distribution of the pressure within the contact area 4. Moisture content of the soil 5. The initial bulk density of the soil mass. The largest forces applied to the soil are due to tractor and implement traffic. While these forces are not the only causes of soil compaction, they are conceded to be the major cause. Since these forces are dynamic, to understand the effect of these forces, the volumetric strain produced by a dynamic load must be determined. In order to conduct the above study, the model of a continuous medium for soils as proposed by Vanden Berg (1958) was used. He defined soil stress as a set of nine quantities in the form of a stress tensor instead of a single value. The stress tensor can be separated into two components, the mean normal stress tensor or spherical stress tensor and the stress deviator tensor. The spherical stress tensor is similiar to hydrostatic pressure and is determined by taking the algebraic mean of the normal stresses acting in three mutually perpendicular directions at a point. The stress deviator tensor differs from the stress tensor in that the mean normal stress is subtracted from each normal stress component. Since any stress-strain relationship will be a complicated function depending on soil type, moisture content, rate at which the load is applied and others, many instrumentation problems are involved. Because of the great need for an instrument to measure the components of the stress tensor at a point in the soil, the major portion of the work presented in this thesis was directed toward the design, construction and development of a six directional stress transducer. The primary objective of this study was to determine the relationship of dynamic forces, mean normal stress and volumetric strain. When this relationship is determined, it will be possible to predict soil compaction as caused by various implements and power units. This information will be a major contribution toward the development of means for controlling soil compaction. REVIEW OF LITERATURE Numerous studies have been conducted to evaluate the stress distribution in soils and the relationship between the stresses and changes in the soil mass. Obviously, if this relationship was known, the change in the state of compaction resulting from externally applied forces could be predicted. The soil stress-strain relationships were recently reviewed by vanden Berg (1958). The deveIOpment of strain-gage pressure transducers led to the first real progress in accurately measuring stress in a soil mass. They have not only been used within the soil mass but at the loading surfaces such as at the soil-tire interface. The performance of the cells reported by Cooper (1956) makes the Type A Cell preferable to other types. Soil-Tire Interface Pressures The first recorded effort to measure the magnitude of the forces applied to the soil by a farm tractor tire was made by Lask (1958, 1959). Small strain-gage pressure transducers (column and diaphragm cells) were mounted in the tire so that the surfaces were flush with the tire surface. The lower inflation pressures gave a more even pressure distribution across the tire. The lugs of the tire carried a larger portion of the load than the undertread. Additional studies were conducted by Trabbic (1959) using diaphragm-type pressure transducers in lugs as well as undertread. The results showed that as the drawbar load and tire inflation pressure were increased the soil-tire interface pressure generally increased on the undertread and leading lug side. The pressure decreased on the lug face and trailing lug side as the drawbar load was increased. The soil-tire interface pressure was measured in a different manner on a smooth tire by vanden Berg and Gill (1959). Larger diaphragm cells were placed flush with the surface in a densely packed sand and a tractor equipped with a smooth tire was towed across the instrument area. Peak pressures occured just as the tire made contact and broke contact with the soil. The highest pressures occured at the center of the tire and progressively decreased toward the outside edge. Soehne (1958) theoretically calculated the soil-tire interface pressures and concluded from measurements made by Kraft for thin-walled tires on firm soil that the surface pressure over the entire contact area was approxi- mately equal to the average pressure. In a study of the Pressure distribution between a smooth tire and soil, however, Vanden Berg (1959) found that the pressure distribution within the contact area was not uniform. He concluded that Soehne's theory of uniform surface pressure can not be used without considerable error since the maximum pressures recorded were twice the average pressure for the contact area. The stresses produced in a soil mass as a result of an externally applied force have been.measured using various physical principles. A U.S. waterways EXperiment Station report, as reported by Cooper (1956), reviewed and described various types of soil pressure cells developed for soil mechanics studies prior to 1956. COOper 33' al. (1957) described a strain gage transducer for measuring normal stress pressures developed by the wheels of a tractor in the soil. Results obtained with the cell indicated that the stress distribution under a rolling wheel was similiar to that described by the empirical equation 0; = Pm (1-cos‘() developed by Hoehlich (1934). Where: 0;'= vertical normal stress Pb: applied surface load °( = polar coordinate. Reaves and Cooper (1959) studied the stress distribution under a 12-inch tractor track and a 13-38 tractor tire carrying the same total dynamic load and pulling the same drawbar load. They found that the stresses under the tire were in almost every case twice as large as those under the track for any position. Pressure measurements were recorded at 3-inch increments from the center line of tire and track laterally 12 inches and downward to 42 inches in Congaree silt loam with the Type A Cells. Also in the same report, results of comparative stress curves at a depth of 9 inches in Hiwassee sandy loam under a 13-38 inch tire and a 12-inch track were presented. They found for the tire a smooth curve of higher magnitude and shorter duration then for the track. The curve for the track showed a vibrating stress which was correlated with stresses applied to the surface of the soil due to the action of the drive sprocket. ’ In experiments designed to determine the overall movement and compaction in a soil mass for the simplified case of piston sinkage, Soehne gt_ El. (1959) found that "at some distance from the piston, lines of equal principal stress appeared to coincide fairly well with lines of equal compaction, but directly under the piston this was not the case". The movement of the soil was determined by placing small lead spheres in the soil and thay plates were made during each test. The method of determining the directions of the principal stresses from the deformation of a grid as developed by Haefeli and reported by Bekker (1957) was used. Willits (1956) studied the stress produced in soils by traffic and the relationship between the stresses and compaction in undisturbed soils. He found that a maximum stress of over one hundred pounds per square inch near the surface of the soil was produced under the drive wheel of a Massey-Harris Clipper combine. The stresses developed by all traffic decreased rapidly with depth. The amount of compaction was determined by taking soil samples and determining the bulk density. The variables affecting the change in compaction were the vehicle, number of passes, original soil density and soil moisture content. Cores of undisturbed soil were subjected to various pressures in the laboratory to obtain the same change in bulk density as was produced by the passage of a tractor in the field. The pressures were similiar to those recorded by the pressure cells during field tests. §Qil §tress~Strain Relationships A number of different theories have been applied to soils. One of the oldest, the Coulomb-Mohr formula (an empirical relationship) discussed by Terzaghi (1959), defines the stresses acting on a plane through the soil mass at the moment of failure. In studies of agricultural implements 47 years ago, Berstein developed a sinkage equation that relates the ground pressure and sinkage of a given loading area. Bekker (1957) modified Berstein's equation and used it in his theory of land locomotion. Soil deformation was defined in terms of certain soil constants "practically independent" of the size and form of the loading area. Using the soil value system developed by Bekker, Stong (1960) found that the soil strength was decreased by plowing and disking. Vehicle traffic increased the soil strength by compacting the soil. Within the range of 10—24 percent moisture content, bulk density has a greater effect on soil strength than the moisture content. Vanden Berg (1960) stated that neither the Berstein equation or the Coulomb~ Mohr formula is a logical basis for a general soil mechanics because they do not relate stress and strain. Using the model of a continuous medium for soil, Vanden Berg (1958) defined soil stress in terms of a stress tensor. The stress tensor was divided into two tensors, the mean normal stress tensor and the deviatoric stress tensor. Applying theories of elasticity and plasticity, he proposed that volume strain is controlled by mean normal stress. Some of the observations made by Vanden Berg are: 1. The concept of continuum will apply to loose soils. 2. Of the four invariants of the stress tensors investigated the mean normal stress related best to bulk density. 3. It could not be concluded that soil compaction is independent of the deviatoric stress tensor. Hovanesian (1958, 1959) found that the density of agricultural soils was related to mean normal stress by the following general formula: “Y: 13 + B ln[(q7fg)+ K/(1+K)] (1) 10 Where: initial bulk density of soil initial mean stress mean stress bulk density :x: 4953‘“ and B are soil parameters, assumed constant for a given soil condition. He also found that for a given value of mean stress, impact loads will cause less change in bulk density than that created by a gradually applied and released load. In static compression tests, Soehne (1958) filled cylinders of outside diameter 11.2 inches, height 5.2 inches and volume 610 cubic inches, with undisturbed soil samples taken from the field or with loose soil. He found that the amount of compaction and the reduction of porosity was related to the pressure by a logarithmic law. The higher the moisture content the more the soil was compacted by a given pressure. When the kneading compaction test was compared with the static compaction of loose soil a steeper slope resulted from the kneading test. The following equation was derived from an analysis of the compaction of arable soils. n = -A log p+c (2) Where: n = porosity 11 A = slope of the curve on a logarithmic scale p = pressure c = porosity at a pressure of 10 psi. This relationship between porosity and pressure is similiar to the formula used in civil engineering soil mechanics discussed by Hough (1957). From studies of the resistance to compression of confined fragmented soils, Reeves and Nichols (1955) found the relationship between pressure and amount of compression to be of the general form y = a e bx where: y = amount of compression x = pressure. Hendrick (1960) found that the tensile strength of soil briquettes did not change for loading rates of 0.18 to 4.70 kg/cmZ/sec. Less strain energy was required to cause failure at the higher loading rates because the briquettes strained less. The magnitude of volume strain may be less from a static load than from a dynamic load such as that produced by a track or a tractor tire. This latter action may cause an orientation of particles that will result in a greater volume strain. Terzaghi (1959) found that vibration 0f sand resulted in a greater compaction than could be caused by an equivalent static force. The effect of vibration on clay was much less because the cohesive bond between clay particles interferes with intergranular slippage. THEORY Using the model of a continuous medium proposed by Vanden Berg (1958) the forces acting on a volume element are completely specified by the stress tensor and volumetric strain by the change in bulk density by ignoring the shearing deformations and rigid body rotation. To define the state of stress at a point requires that six independent values be determined. The volumetric strain can be deter- mined by measuring the change in bulk density. The stress vector on any arbitrary plane can be determined by using matrix algebra (murnaghan 1951. For example problems see Malvern 1957). For the following conditions, 1. a plane oriented so that its normal lies in the Y Z plane and bisects the angle formed by the positive Y and Z axes, . 2. a plane oriented so that its normal lies in the Y X plane and biSects the angle formed by the positive Y and X axes, ‘ and a plane oriented so that its normal lies in the X Z plane and bisects the angle formed by the positive X and Z axes; the directions cosines of a normal vector to each of the Planes are, respectively, 13 1’ 0' [IE/2’ ”/2 ’ 2° VIE/29 VIE/2: O 1 3.13/2. 0. 1372. For the general stress state the stress tensor is 0; ts tn .13!!! T3} Zyz (3) (my. my 0;. If 1, j, k are unit vectors along the pos1tive X, Y and Z axes respectively, then the components of the stress vector acting on the three planes described above can be obtained by matrix multiplication. For plane one as defined by condition one the stress A vector-r} is U} 'tmy ‘Zkz -h. T1 = (0.1272. 1272) fxy 13 232 rm 2’” 0‘7. = fi/Za’XyJXZfi . (ii/goat”) ‘3 +{5/2(Z§z+03> 3?. (4) For plane two (condition two) .4. U} 29y 2&2 T2 = ((5/2, fi/g. 0) 23W 03 232 ’Z'xz Z’yz 02 =f2—/2(fi+2’xy) '3 + fi/2(ny+q§) .3 + fi/2(sz+zyz)-E’ (5) 14 For plane three (condition three) _§. 0; 'txy 2x2 T; = (43/2. 0 .5/2) 23w 07 fyz ‘le Z52 0?: =V§)2(0§+2&z)'§ +7572(ny +Zyz)'3'+{§7é(2§z+02)'§2 (6) If the scalar product of a unit vector A; in the‘direction of the normal to the plane and the stress vector T; acting on the plane is determined this will be the magnitude of the normal stress acting on the plane. The normal stress U11, acting on the plane can be obtained as follows; for plane one the unit normal vector is, :3 II A 0:11 = 3:1"; (733’ - sUSwU'z) + Zyz (7") for plane two the unit normal is, —I I .- - -" 32:5/2i+fi/2j+0k then _;§ 032 ... 3‘2 .T2 (8a) UB2 = %(Ul+03) + 23y (8b) for plane three the unit normal is, A -.> -.- “ n3 = {572 i + O 3 + 45/2 k 15 then, d. 0:13 2333.1 (98.) 033 = %(Vi+fih) +‘sz . (9b) The principal stresses can be determined from the stress tensor for the general stress state, however, it is easier to determine the principal values of the stress deviator tensor and then calculate the principal values for the stress tensor. The stress tensor can be separated into a spherical stress tensor and a stress deviator tensor as follows. 0% ny 1&2 Um 0 O Ul-Ud 29y 2&2 fxy Ty zyz = O “—111 0 + xxy 65-07:: tyz (10) fxz fyz 0‘2 0 0 fix {x2 tyz (Ta-1?; Stress Tensor Spherical Deviator Tensor Stress Tensor Where: "a = 1 (Ui+03 +02) (11) If Si denotes the three principal deviator stresses, the following relationships are known: 67-07:: (12) 52:52-57} (13) 53:93-73 (14) 079 W5: and V? are the principal stresses of the stress (I) _5 N 16 tensor. It is possible to rotate the coordinate axes to such a position that all of the shear stresses will be zero and only these principal stresses will act on the plane. The problem is to determine the direction cosines nx, ny, and n so that this condition is present. If '3’ is a unit 2 vector in one of the principal directions and S the magnitude of the stress vectorzfi, the stress vector on this plane must be parallel to ‘3 since there are no shear stress component on the plane perpendicular to ‘3. Therefore, A 13:33” (15) The three components of this vector equation can be determined by matrix algebra as follows Sx-S ’2’xy fxz H (nX, ny, nz) Z’xy Sy-S {yz fxz Zyz SZ-S ° = 0 1’s (Sx-s)nX +23x ny +1kx nZ ( o ) fxy nX +(Sy-S)ny +2’xy nz = 0 (16b) 2&2 nZ +2yz my + (SZ-S)nz = O (160) Where: S = 111;, 3y = 03-62;}, and SK = 02-0; This is a set of three homogeneous linear algebraic equations for the three unknown direction cosines nx, ny’ 17 and nz. The directions cosines must also satisfy the equation 2 2 2 nx + ny + nZ = 1, (17) and, therefore, all three cannot be zero. A system of linear homogeneous equations has a solution other than the trivial solution if and only if the determinant of the coefficients is equal to zero, that is, if Sx" S tyx z'zx ‘fxy 8y 1 'sz {yz SZ-S (I O -S 22y (18) Expanding the determinant gives a cubic equation in terms of the unknown magnitude 8; s3 - II s - III = O (19) s S where IIS and IIIS are algebraic invariants of the stress deviator tensor and are defined as follows; -: >21 )2 ‘1’ (.3y "Z 2 , 113 = lusx-sy) + (Sz-sx 6 2 2 2 +7332 + YZX + ny (203) Substituting Sx = Vlfflli 8y = F; ' Vtv 5% = V; '5; 3 118 = _1_[(9'§c-03,)2 + (03, 41212 + "'2 ““3023 6 2 2 2 20 + ny + 72: + ny ( b) 18 53 Zsy‘ 7&2 Uk-Oh. Zly ¢§z IIIS 2’yz sy fyz t’yz V3; 4,; {yz (21) I ikx 12y Sz) ‘tsx Zéy V3 —0B 11 H The roots of equation (19) are the three principal stresses. The solution may be obtained by making the substitution (malvern 1957): s = 2(coso0 II8/3. (22) From this substitution.the following relation is determined: / (Us) 2 Then 30(1, 30(1 + 277', and 30(1- 277' all have the same cosine given in terms of the invariants of the stress deviator. Thus the three roots of equation (19) are: I) II II 2(COS°(1) 8/3 II 52 = 2(cos°(2) 3/3 II S = 2(cos°<3) 8/3 Where: 0(2=o§+277" and o<3=0<,- L73: 3 Now the principal stress values can be determined by using equations (12), (13) and (14). The values that are obtained 19 are ordered algebraically from largest to smallest and designated by E, (El, and (TI-II respectively. The maximum shear stress, which is a function of the stress deviator, is given by Z’max = afi-an) (24) In order to vertify the hypothesis that soil compaction developed under dynamic conditions is controlled by mean normal stress two things must be demonstrated: 1. That mean normal stress does correlate with bulk density and 2. That the deviator stress tensor does not correlate with bulk density. The only measure of the spherical stress tensor is mean normal stress. many expressions can be used as a measure of the deviator tensor. Since earlier investigations have indicated a relationship between maximum shear stress, maximum normal stress and bulk density, these relationships will be investigated. APPARATUS AND INSTRUMENTATION Design and ngelopme t gf‘g Six Directional Stress Transducer Two different models were designed during the development of the six directional stress transducer (6 DST). The first model designed consisted of a small octagonal brass box with eight sensing elements as shown in Figure 1. Each of the sensing elements was to be made of 0.025 inch thick stainless steel with two Type A-18, SR-4 electrical resistance strain gages cemented to the element. The diametrical pairs of sensing elements would form the four components of a Wheatstone bridge. With this arrangement maximum sensitivity and temperature compensation would be obtained. Construction of several sensing elements revealed that pieces of stainless steel of this size and shape were difficult to work. In addition, since the element was designed to act as a simply-supported beam, the problem 0f protecting the gages mounted on the element without restricting the action of the beam was not satisfactorily accomplished. Due to these difficulties the second model, the 5 DST, was designed and constructed. (Figure 2) A hollow brass sphere (3 inches outside diameter and 1 7/8 inches 21 .8 SIDES MACHINED TO .025 3’ _ . CROSS SECTION TOP VIEW .6. |§ -4— § 4 --<-—-§--,J ‘1 4 M19 +<-->-I III *3 I6 i 12 ’2 T— P——f—'L ‘ ‘ I _ u M0 \ + I ‘ 1‘ 1 T :3" . 'r 12 .. \3 i ' 3 "I" '1' T 1’ 5'” ’ T ’r \‘F -Iv EN 52—...) 3 T no 0 DRILL I'e' g-Isuc-z 'e' I“ éloEEP- 4 HOLES } nun-4 HOLES FRONT VIEW TYPICAL SIDE VIEW 2 A-IB 33-4 NOTES: -.v . 6/— 37““ ““553 SENSING ELEuEuT MADE or ”NT—l M —_ .025 STANLESS STEEL | E7 ~‘5 DRILL. Tun“ TAP HOLES FOR A NUMBER 3" 5’ , J oeux 92°10 2 FLAT no sanw 1+— I- .199 mA SCALE FULL SIZE Figure 1. Detail drawing of the Four Directional Stress Transducer. 22 3 DRILL c'soRE 3- CIA TO 2; DEPTH- 6 HOLES EQUALLY SPAOED DRILL 3 HOLES QUALLY SPAOED MOI” DRILL c'soRE FOR-2'- HEX sooner @193 TOP VIEW :2 PRESSURE CELLS wn'n REDSHAw STRAIN GAGE / SENSING ELEMENT SCALE : . 0 Rune FULL SIZE CROSS SECTIONAL VIEW 1”Laura 2. Drawing of the Six Directional Stress Transducer showing the Location of Diaphragm Pressure Cells. 23 inside diameter) was cast in two parts. The two halves were machined to permit the use of an "O“ ring for a waterproof connection. A 3/8 inch hexagon socket head bolt was used to clamp the two hemispheres together. Six diaphragm pressure cells capable of measuring normal stress were located in each hemisphere. Three of the pressure cells are mutually perpendicular and the other three are oriented in the planes that bisect any two of the three mutually perpendicular directions. When the two half spheres were connected, the corresponding cells in each half sphere were oriented diametrically opposite each other. These pairs of cells were connected to form two legs of a Wheatstone bridge. Two 120-ohm wire resistors were used to complete the Wheatstone bridge. The diaphragm cells which were used for the sensing elements were constructed in the following manner. A length of 3/4 inch diameter cold-rolled steel stock was chucked in a lathe and a 5/8 inch hole was drilled through the center of the piece. An 11/16 inch drill was used to enlarge the hole to a depth of 1/16 inch. A 3/8 inch long cylinder was then cut from the length. Diaphragms made of 0.010-and 0.020-inch thick stain- less steel were rough cut to a one inch diameter with a metal clipper and soldered with stainless steel solder to the cylinder wall at the end with the 11/16 inch inside hole. Finally, the cell was chucked in a lathe and the 24 diaphragm was machined flush with the outside diameter of the cell wall. After the cells were constructed, a Saunders-Roe foil strain gage (Redshaw 1/2—2 ED, 25 ohms, gage factor 2.1) was cemented to the inside surface of the stainless steel diaphragm. Since the Redshaw strain gage does not have lead wires attached as the SR-4 gages, a method for attaching lead wires to the tabs of the gage had to be devised. After several preliminary tests the best method found was to attach a piece of copper wire to the tip of a soldering gun. The tabs were tinned prior to being mounted on the diaphragm and after the curing process a 2-inch length of wire (Belden No. 8430) was soldered to each tab. The gage was waterproofed with a thin layer of wax. To protect the strain gage from being damaged by a force applied to the lead wires, a rubber stopper was cut and placed in the open end of the pressure cell. The lead wires were conducted through a hole in the center that was sealed after the stopper was in place. A four-conductor shielded cable (Belden Strain Gage Cable No. 8434) was connected to the 2-inch wires to carry the signal to the amplifier. The calibration device as reported by Lask (1958) was used to calibrate the individual cells. The maximum design value of 60 psi was selected since this was the maximum pressure recorded in the soil by present agricultural 25 equipment. Calculations indicated that a 0.010 inch thick stainless steel diaphragm 3/4 inch in diameter could be used. A problem was encountered since the Redshaw strain gage has only approximately 25 ohms resistance. The amplifiers and associated equipment available for conducting the experimental tests had a range of 50 to 500 ohms. Several calibration tests were conducted using different bridge arrangements to determine if the bridge could be balanced and the order of magnitude of the gage output. A calibration curve for the 0.010 thick diaphragm using a 120 ohm wire resistor in series with the Redshaw gage is shown in Figure 3. The results of three tests show a linear relationship up to 25 psi. Within the range from 0 to 25 psi, one line deflection represents approxi- mately 2 1/2 psi. As it was proposed to use two active gages in each bridge the sensitivity of the bridge would be doubled or one line deflection would represent 1 1/% P81- Since the relationship was not linear up to 60 psi, it was concluded that a thicker diaphragm should be used. A series of tests were made using 100 and 120 ohms resistors in series with the 25 ohm Redshaw gage mounted on a 0.020 inch thick diaphragm 3/4 inch in diameter. The results of three of these tests using a 100 ohm resistor are shown in Figure 4. A linear relation was obtained up to the maximum value of 80 psi used during the tests. One 26 Hopes—mun o kanmomm no.“ ohhdo somewaflgw\m.m_wshnndfin an. I mmammmmc a tee: om 0 minus. _ _ l 0 «29mm: Immi Cow. mgfimwowm! ¢ mo o>< L _ 0— 0. 2th 85".ch n 52 mmz... 8 325.30 , _ r _ 3.3 wzwsSmhemZ ON 0N — NOLLOB'L-JBO saNn 27 MOHSB A05 0.0.0.0 GO GQP§OS 0mg fidhpm tdfimcmm .HOH 0>H§O QOfiFGHDHHdO £3339 5 sons {a assesses .e enemas .md mmnmmmma omjaad. 8 2. 8 on cc 8 ON 0. oo «Sammy. mofifium was, Com. mmi Com. 1: m n N N woes $98 as. Gas 38 x r. . 555mm «055% m. m. was, Coo. mmi Coo. M . B .rzmsmozqmmd mama m do mac muemm mm3<> o>< n... .vmnNu N 0 N» m 2C4 825.5 n 2»? $2... om ouEmmJS <._. o>< cum _ N nu 4 Nm N 2.72 ombummao N Z._.._.< mmz... ON ow... , 5 I I -o , _ I A . I I I g IO IS 20 25 APPLIED LOAD PSI Figure 58 . Comparison of the Two Instruments Used to Measure the Vertical Stress with Theoretical Values at a Depth of 15Inches below the Loading mrface. Measured Data obtained from Test 15. The curves for the 15-inch depth are shown in Figure 58. The theoretical and Type A curves again are in good agreement for a concentration factor of four. The maximum percent difference is only 7.75, which occured at the highest load of 21.6 pounds per square inch. The values obtained with the 6 DST are lower than the theoretical and Type A values for loads less than 12.0 pounds per square inch. Above 12.0 pounds per square inch the differences are greater with increased loads. The maximum difference between the Type A and 6 DST values is 27.55 percent as compared with 36.68 percent between the 6 DST and theoretical values. On the basis of this data the conclusion that both instruments gave higher values than the theoretical values for loads greater than 12 pounds per square inch could be made. In addition the 6 DST gave measured values greater than the Type A values for loads greater than 12 pounds per square inch. The differences between the theoretical values and measured values could be due to the differences in their volumes which may interfere with the stress distribution in the soil mass. CONCLUSIONS In the loose soil used for the experimental tests, data presented indicate the following. 1. 3. The data obtained with the Six Directional Stress Transducer were more varied than that obtained with the Type A Cells. The hypothesis that changes in bulk density are controlled by mean normal stress cannot be accepted or rejected. The data obtained for both methods do not support completely the part of the hypothesis that the second invariant, maximum normal stress and‘ maximum shear stress are not related to changes in bulk density. The maximum shear stress was best related to changes in bulk density. For the 0.38 inch per.second rate of loading, a range of moisture content from 7.97 percent to 16.16 percent had no effect on the relationship between mean stress and bulk density. The moisture content had an affect on the,- relationship between mean normal stress and bulk density for the 0.62 inch per second rate of loading at depths of 10 and 15 inches below the 10. 11. 12. 137 loading surface and the 1.00 inch per second rate at the 15 inch depth. The relationships between the invariants and bulk density at the higher rates of loading at the 15 inch depth were affected by the moisture content of the soil. The mean stress-bulk density relationship was not affected by the rate of loading at the three depths below the loading surface. The values of mean stress obtained directly with the w Cell compared best with the values calculated from the Type A data. The lowest values of mean stress produced in the soil mass for a given applied load occured under the 1.00 inch per second rate of loading. The vertical stresses measured with the Type A Cell were in good agreement with values calculated with Froehlick's equation at the 10- and_15-inch depths. . The relationships between the invariants and bulk density were exponential. REFERENCES Anonymous (1958). Soil compaction committee report. Joint American Society of Agricultural Engineers and Soil Science Society of American Committee Report. Agricultural Engineerin539z173-176. Bekker, M. G.(1960). mechanical properties of soil and 'compaction problems. Unpublished A.S.A.E. Paper No. 60-126. St. Joseph, Michigan. Bekker M; G.(1956). Theo of Land Locomotion university of‘Michigan Press, Ann Iffior.‘520fipp. ’ Cooper, Arthur W.(1956). Investigations of an instrumentation for measuring pressure distributions in soils. Thesis for degree of Ph.D., Michigan State Univ., East Lansing, (Unpublished). Cooper, A. W., G. E. vanden Berg and H. F. McColly (1957). Strain gage cell measure soil pressure. Agricultural Engineering 38:232-235, 246. Gill, William R.(1959) Soil compaction by traffic. Agricultural Engineering 40:392-394. 400. Hendrick, James G.(1960). Strain energy and tensile strength of a dynamically loaded clay soil. Thesis for degree of M.S., Auburn Univ., Auburn, Alabama (unpublished). Hough, B. K.(1957). Basic Soils Engineering. The Ronald Press 00., New York. 513 pp. Hovanesian, J. F.(1958). Development and use of a volumetric transducer for studies of parameters upon soil compaction. Thesis for degree of Ph.D., Michigan State Univ., East Lansing (Unpublished). Hovanesian, J. D., and W. F. Buchele (1959). Development of a recording volumetric transducer for studying effects of soil parameters on compaction. Transactions, A.s.A.E. 2:78-81. Lask, Kay V.(1958). Instrumentation and measurement of soil-tire contact pressures. Thesis for degree of M.S., Michigan State Dniv., East Lansing (Unpublished). 139 Lee, G. H.(1950). Ag Introduction to E1 erimental Stress Analysis. John Wiley andfgbns, Inc., ew ork. Malvern, L. E.(1957). Introduction to the mechanics of a continuous medium. unpublished notes for graduate course in Applied mechanics Dept., Michigan State Univ., East Lansing. ‘ . murnaghan, J}(1951). Finite Deformation g£_§g Elastic Solid. John Wiley and Sons, Few YorE. Perry, C. C. and H. R. Lissner (1955). The Strain Gage Primer. The maple Press 00., York, Pa. 281 pp. Popov, E. P.(1958). mechanics 2; materials. Prentice— Hall Civil Engineering and EEgineeFIfiE'flEEEanics Series, Englewood Cliffs, N. J.. 441 pp. Reaves, C. A. and A. W. Cooper (1960). Stress distribution in soils under tractor loads. Agricultural Engineering 41:20-21, 31. Reavcs, C. A. and M. L. Nichols (1955). Surface soil geaction to pressure. Agricultural Engineering 36:813-816. Redshaw, S. C. (1954). A sensitive miniature pressure. JOur. 3: Sci. Inst. 31:467-469. Reed, I. F., A. W. Cooper and C. A. Reeves (1959). Effects of two-wheel and tandem drives on traction and soil compacting stresses. Transactions, A.S.A.E. 2:22-25. Rosenbach, Joseph B., Edwin A. Whitman and David Moskovitz $1243). 21223 Trigonometry. Ginn and Company, New Ybrk. PP. Snedecor, George W. (1956). Statistical Methods. 5th ed. The Iowa State College Press, Ames. 534 pp. Soehne, W.(1958). Fundamentals of pressure distribution and soil compaction under tractor tires. _Agricultural Engineering 39:276-281, 290. . . Soehne, w. H., w..J. Chancellor and R. H. Schmidt (1959). Soil deformation and compaction during piston sinkage. unpublished A.S.A.E. Paper NO. 59-100. St. Joseph, Michigan 140 Stong, Jack V.(1960). Basic factors affecting the strength and sinkage of tillable soils. Thesis for degree of m.S., Michigan State Univ., East Lansing (Unpublished). Terzaghi, x.(1943). Theoretical Soil mechanics. Jehn Wiley and Sons, Inc., New YorE. 515 pp. ‘— Timoshenko S.(1936). Theo§y of Elastic Stability. MCGraw Hill Book 60., new YOrk. p57 Timoshenko, s. and J. N. Goodier (1951).' Theor of Elasticity. McGraw Hill Book Co. 2nd ed. New York? Trabbic, Gerald W.(1959). The effect of drawbar load and tire inflation on soil-tire interface pressure. Thesis for degree of M.S., Michigan State Univ., East Lansing (Unpublished). Trabbic, G. W., K. V. Lask and W. R. Buchele (1959). measurement of soil-tire interface pressures. Agricultural Engineering 40:678-681. Vanden Berg, Glen E.(1958). Application of continuum mechanics to compaction in tillable soils. Thesis for degree of Ph.D., Michigan State Univ., East Lansing (Unpublished). Vanden Berg, G. E.(1960). Requirements for a soil mechanics. Unpublished A.S.A.E. Paper No. 60-127. St. Joseph, Michigan. vanden Berg, G. E. and W. R. Gill (1959). Pressure distribution between a smooth tire and soil. unpublished A.S.A,E. Paper No. 59-108. St. Joseph, Michigan. Weaver, H. A. and V. C. Jamison (1951). Effects of moistuge on tractor tire compaction of soil. Soil Science, 1:15- 3. - Willits, Nathan A. (1956). measurement of pressures in soils produced by traffic and the relationship between those pressure and compaction in undisturbed soils. Thesis for degree of Ph.D., Michigan State Univ., East Lansing (unpublished). 141 Wilson, S. D.(1952). Effect of compaction on soil properties. Proc. of the m.I.T. Conference on Soil Stabilization, 84-161 pp. APPENDIX TABEE A. CALCULATED VALUES OF MEAN NORMAL STRESS, SECOND INVARIANT OF DEVIATOR MAXIMUM AND MINIMUM PRINCIPAL STRESSES, AND MAXIMUM SHEAR STRESS ROR THE TYPE A CELLS AND THE S IX DIRECTIONAL STRESS TRANSDUCER STRESS TENSOR, Bulk Load Density 6 DST 0?. (psi) (psi)‘(psi) (psi)-(psi) (psi) Type A Cell V3: 12:: (psi) (em/cc) (psi) (psi)’(psi) (psi) (psi) (psi) “Z 93 3 V7» 0:... .22: TEST 1 NONmeP s s s s s s NOOWF‘G‘WO FFNNN d'mkol‘COPM O O O O O O O v-s-NMO‘PN v-moocxunoo FFF merwvoo . O O O 0 ONd‘WOO‘O" Pv- v~b<3bo Q 0 O O QPNNfi'd'KO QMKO 0N mm "' PFN £11 TABLE A (CONTINUED) 6Dfl fink Load Density (psi) (gm7cc3 (psi) Tpsi Sufi“) OWN ““0 ‘- mbxo O‘NOON ONMQONN "GNP-(“#0 OOC|>C?OO"' bflDdDQHDKMfi 0000.0. C>F1ur¢mm mmv-oxoxom PMPO‘ONM v-v-r- MMPQOKO“: PMV’U‘P’I‘G) OO‘MMQOU‘ . . . v-v-NM‘dWOt‘ MFNNMfl'U‘W 0.... F'N 145 m¢w¢ FPNF O\O\O med' N LDI‘O FMfl' PNCD C‘O‘KO m PMd’tfiW ozoo N mmmmoot: FNMd'mkal‘ PMC‘VOO PO . O . . . . . PMd’LfikO [‘CD meN¢FF .00.... ¢0 P NPOC‘O‘ o o o o PNMMV I‘mmmV OPNMV Od-mooo O O O O O FNMVkD NOMVN . . . . . mmCOV'V PP A °H m Q3 SDMT (psi) (psiT‘umi) (psi) {M TABLE A (CONTINUED) 111' (psi) (psi) (psi) e A Cell Egfifi (p812 (gm/EC) (psi) (psi)‘ Mm 1 1 07.2, Eflk Load Density bmmwo Pmmbo ,. FmNNm' OOPNN Cszlhln ONNMd’ \OLOMM" O O O O O MPNWN me MMQFM , MMMNM mei- m¢¢¢® mebm M8 ¢MMN® .0000 FMMPQ mOVOm OFFNN mmomo 0000. memm NPPMP MP’NKON PPN \ONFM" NMMOM FMKOF mmmd'd’ mebm «30‘me 0' O O O O (Jr-NM? O_OPP\O #010611"? Plhanln PNMLOKO MKDMIDC‘ Pmmbw Nhrbm OOPPN OFM0wv ON NMd’lnm Mv-mxov—q-p O o o o o o o NmOmf-kom PPNNN NO Nl‘l‘wm 0 o o o o o o Pfi'MNWF’d' Nmoumn PP OCNONI‘NO PN Lnl‘mNd' P‘- Chm NNMONM O ‘- Mfi'lfilnfi COLAMI‘O‘NO OPNMdWOP oomomv-MN Ownewmb ©¢>P©OP 00000.0 NIDCDNLRQ)" v-v-v-N NKOLAWNLDLA o O O O O O O Pfi'Ni-Q'Lno "’N¢"\'-:t'ls d'ONb-QO‘NO F(\l «rxoooom . v-r- ve-(o mFNMM V'" FNNNN O C I O O O 0 P1- Pv-v-v-r- ""N NMVI'MKO MKO O‘Nlhd)" FFPN 62 Omr-Mcncom F’N “\me :- PP PPNlhd'COv- OOPNMd'kO NO LhMN tho ONNMQ‘IAP Nl‘MFdQ-v- O O O O O O O NLnF'l‘MkoON FFNNN F’\O\O\ONM¢ O C O C O O O "WOOI‘Mv-m M‘ONMO OQOWNNO PNMI‘ONV‘ v-v-v- comment-Coo OFNMfi'kOO moo MMQQM OFNMd'InF COOPOKOF' Pmm¢mmw “\LAN rmnmm NIDCOFMP'O PFC-N CDMNFO‘NN O O O O O O O o-d-oownnoo FW-or¢U\ “\meth PMd'kOl‘ON F!— mwONNMM FPNNNNN O O O O O O O PFFT‘FPF MPNNMd'lnkO 91M“) OWN moo "" FFPN moo «mom-to OPd-komv:c\| PP NNCDPONOCO OPPNNfl'm ®®¢OPmm OPNMd'd'kO "CO\O\O<"¢O NVOmF-PO PFNNM OPPOVU‘M PMd-d-PNP- NmOl‘m Oxooxounnm- FN¢>mN¢ P1- Pdwov-v-Nl‘ "N MMOI‘P OOQK‘MMO FNNMQ’IDI“ "OFONOM FNMVIAWP' NQOCHOI‘IA M\OOM\O O‘N \DPb-PInMP Phxod-xomco 'FMd'kOt‘ MW MNQ MM FMDI‘QON P1- Inmv-NMMM PFNNNNN O O O O O O O Pq-v-r-v-s-v- Q'PNNMQ'U‘K) 90M“) CNN moo ‘- m PPFN TMflEA(mmemm) 6D$§ E§T (psi) (psi) (psi) (psi) Hflk Load Density lfi, Txpe A Cell vii Vii £29! £3 (psi) (psi)‘ TE tow :—: (psi) (gm/be) (psi) (psi)’(psi) (psi) (psi) (psi) PVCOLRF'LOM f-NMLnt‘OF Pv- Nfi-PmmF-d- OFNMfl'mm FIAMCDI‘V'P OPNMVMI‘ mFmePm O O O O 0 O 0 Nmowrcoxoco PFNN Vd’l‘l‘NmN .FI‘QONWfi'fi' PMKO NNOOMPPP 000.000. PMMPO‘Pfi'kO NNNMKOO‘O" ou-mxov-Inooxo v-i-NM b-OONQWOI‘CO C O O O O O O O on-d-mxooom mOOOOPF'P PPNNNNN 0 O v-v-v-v-Fr-P TABLE A (CONTINUED) T e A Cell fink Load Densitz 5"; a E 32 1...; (psi) (gm/6c) (psi) (psi) GDMP EL_JEL_JEi (psi) (psi)‘ f“ w m g V A w m g V A H Hm 90 V A a m g V ’(psi) (psi) (psi) (psi) NLRN EMF-F? V‘N d'lnb-O‘ON Pv- M'F'I‘M‘O ¢M¢ O COOPNM .‘?u \0 PV’U‘OMFN O PNN MMV'V OFCOCDMI‘PM NfihPmOMw PPNNN vmmwwowm 00...... mehmmom mew¢m memvao OFMVWOQON Pv- V'MOQ ¢NON O O O O Or-NNMd'lnln (or-«3mm PQO QFPNMVd'W I‘MO‘GDONFNO or-v-NMQWOK" ¢>>PPmm¢ PMIDCDONVIWO v-v-v-v- NOPOMQmO oooooooo ONmO¢Pmm PPNN"\ 154 OV'V'O "O‘NU‘ PFMmPQPM F1- NNOVPP¢F OIOPFV‘NNN MONO‘NK‘T‘“ OPFPNNM¢ (DOQIAQONK‘ O O O O O 0 O O PMb-FmOV‘m PPNNN PFOmed'In O O O O O O O O FNMNMNF“ PM\OO\OM PPN \OQ'MONW MNN OwMfiWOQON FF InN mMOO‘P‘V' O v-PNMMfi'lh PNCDNKDPCOO" off-PNNMMd' (“MCOMVNQM O v-I-NMV'lnkD \ommmb-oou: PMMWQFMW‘ Pv-v- Mbw FmPO‘l“ ord'b‘OQV'M V's-'NM ooommwmo v-N MMfiml‘O‘ d-v-NNMQ‘WWP; mmmmwmww¢ PFNN mh¢o¢wm> v:v-rmmocoow P‘- F v-mmmmmm O'OOPPFNM NNOFO‘FMQ 00...... OPPNNMMV NQQMN #10“) 0 O O O O O O PMP-FQ'O‘MQ) PPFNN MMfi'Q I‘QQO NMV’OQ mm P vaoxmo PN N\O¢O\NNON OPM¢mQON 1-1- MFQ‘OMVNG O PPNMVMD MVOONOPO 00...... o PNMMVVWO ml‘Pokolan- OPNMM‘dWOK‘ mmmONQOQ FMMQONIDK) PFPP VMOQIDQQN . C C C . O C O o r-q-comwrom PNMM wNNmbPPO 00...... mmPNMMMd’ FPNNNNNN ooooo coo v-v-r-v-v-v-f-P mv-NNMd'lnmC‘ giMW CNN moo P'fi' m PPPNN TumEA(mmmmmm) 6Dfi? a.“ '-e A Cell . (psi) (psi)‘(psi) (psi) (psi) (psi) NET9 aoonv-oomm OPMWK‘OO P'- vamwoh o'.°ov-NMM ‘mequm OPNMMfl'm mPOV-QMV PMFNPM‘“ Pv-NN P‘OUMOOKJO O O O O M”.- Omm ON Pmbmm FO‘mb-‘D “In olefil‘O" Pv- 65 mePOO‘P .00.... O r-cmnoocm- P OmQOOtQ COOPNNN bait-PNv-m OPNMMi'In (news-homo O O O O O O O v-Mbv-Qv-ln PPNN [~er Fww 0...... ONwmmmm PN>P¢ PP «DOVOIAPV'F OvaPO‘P P \OPMFOMN O PMInbO‘H- F MOMQNi'M OFFPNNM O‘NMO‘NmQ 0...... OFNNd’i'Ih \OMmONOK) O O O O O O O Pd-Fva-ln FPNN *OWMQ'PO PMInOln v-q- mmmxotnvxo ONMU‘K‘O‘P , P (psi) (sm/bc) (psi) (psi)‘(psi) (psi) (psi) (psi) aux Load Benoit MMMNON ooxotmnund-m mMNd'mb-M 0.000 0000000 '0000000 OPvamm OPNMQ'UMO (>vaQO mMNNNOa) bmmv-bnnn PO‘PKDK‘CDN 0.00000 00000.0 .000... OPNMd-u‘un OPNMMvm OOPNNmm OCOIANNMV' ObmmNNO meNOOF 0...... 0.00.. 0...... PPNMQ‘MKD PPNMQ'IAKD OPNMd'mm nmNb-moxo M\OU\N€DMM \OMOMMNQ .0... 0.00000 ~0000000 Nd'h-O‘Nmb: Nd-b-ONtnw wav-d'l‘v' PFP PPv-I- PPv-N O‘b-OPOV'O" PONtov-O‘b: PNFPMQQ 0...... 000 '0000000 d'M M OMQIDH‘3K3M PWNMPd' oanNfid’ PNMIn v-qun P MmOVro‘tO‘ MonOO‘MO‘ GNOOFr-bq- 000.000 0 0.. 000.000 PN‘nmbwm Fmémwwm v-Nvunb-aog mPNNMMM Inks-(uncut mmopmm‘. PNNNNNN v-PNNNNN PFNNNNN 000000 .0000 0.00.00 PPFPPPF PFPv-I-v-v: PFPPPPP «wwwnvms Ntasetea ”twaetoa O “éd&&fiéw pmmmwag nnmmNmmg TABLE A (CONTINUED) 7 Y6DST r (ps1) (ps1)’(ps1) (ps1) (ps1) (ps1) .un. '3 2 (em/so) (ps1) (ps1)‘(ps1) (ps1) (ps1) (ps1) A re ‘A Cell I Gav (psi 711111: Load Benoit POiOOan-P ONMU‘QO" PF (oxomb-xomm OOPFPNM OCVNNMO‘ PNNMMQQ orbvth Nd’QMQNw PPNN \O MPCOW MN Od'lnomd'w PQ'CONIA PF NV'NPOQP FNQWOQO‘F' P Re 22 $6 O‘O‘QKOMVWO NOPONRO¢ OFPPNM¢ QMNQV’O‘F OPNNMMd' O ml‘wal" o o o o o o NVQMI‘Pm QMQMOQN OVmO‘F':®. PMb-Pd' PP Owen-0000mm 000‘. PN¢mbmw P OO‘NOWOQ PFNMQ‘MW (DIAMO O‘NM o "NMMV’M CDCDNNONK~ PNM'é'InWP: PNNPOOQ. NmQOMWQ. PFC-P TEST 10 #oonmmmr 00...... OPNMVWOQON NQNN P‘OW" OOOFFPFN MO‘U‘OW PG) N 00...... OOFNNMMQ' PQQQPWNV’ PN #FOQ‘Q" PPPN NPmMPNO‘O‘ o o o o o o o o QPQ'MMPON PNMQ" P mv-Q-l‘ko #0101 or-NMVWDI‘O‘ QKMOOV'MMG' QPNM‘WQWP WOMNMK‘PV’ OPFNNNMM PNOQ‘ONd'OQ OPPNNMd'Q' PMWPPMmN N #00 :MU‘Q CDMWMQMF’P o o o o o o o o OMQPMK‘QQ PNMQWO TMEEAJMMEWWD) eACflJ Eflk Load Densit r— 0" fat-Q1: (psi) (gm/6c) (psi) (ps1)’(pai) (psi) (psi) (psi) (psi) (psi)‘ (psi) (psi) (psi) (psi) .MK‘WOO‘MNWQ OPNMIDC‘QO‘ .FOINDONV-v- OOOOPPPN MPWPMQ *0 ‘00000000 OHPPNNMV’ NM\O\OI~\O (~00 00...... FMIAQFMCD" PFPN MQC’NOV‘OO‘M ONP-QMNQK‘ meom" P MMWFOU‘CQM OPNMlnmPO‘ \OQ'OP'V'MOO: CFNNM¢|nln MOQMQMFP OOOOO'... OPFNNM*¢ (”N cmnm PM” 000‘..... O 1- PN MMQ'Q' cocoaoxoxoosmm PMU‘PO‘FVWO v-v-v- mmONMPNN o o o o o o o o memq-mmxo PNM" 57 (”WOQN v-(nbm 00...... O "N VWOQQP F OPFNmfi'l‘M OQOOOOO" VMQNMPW" OFFNNMMQ' 'd-Pb-b-meN PmmCONPOV PFNN (N0 "300 O‘PN ONCOONMOW “3"“ P1- \0 fink-(WONG 00...... O PNMU‘I‘CDOW PPNQQQQW o o o o o o o o OFNNMQ’U‘W PNOI‘ChO‘NO‘ 0F:NNNM¢<’ m¢wmmwmm O PNNMd’VU“ O mmmxo V'Q" N exocoommao Lnlh‘OFO‘OON .0000. OMWCO‘O‘NU‘ PNd’ln N #mxoxo v-cmn PN Mfl'ml‘wm mv-NNMV'U‘KOI‘ gmmmNmQFV m PPNN \OKDWF-MNwfi' OFNMLQQC‘F P PP¢®®M\OO\ OOOOOPP“ "2066) Pkofid'o OgPNNNMd' NNb-Nd'l‘Pw O O O O O O O O Pmmwv-PPQ- PPNN V'lnlnlthw "' ONPU‘NNPO‘ PMQPM P1- Lmnxobmm b-N QFNMfi'b-Q'O- PW MMOQ OVA 0 PNMV’Q‘MKO MFQNQFIBO OPPNNMfi'm \ONQQMNNO . o o o o o o o on-Nfflfi'ln‘b ONl‘wl‘NNO PVWOQOMQQ PFPP mwwfimmNm o o o o o o o o OMQC‘SQQMN Old-tn O(\1<'\D(*CD\‘>I~ PN (“#10me mv-Mfi'lnl‘l‘w OPPFPPFF o o o o o o o o Pv-Pr-v-v-Pv- QPNNMGMWP QM‘O 0‘wa PV’ 0:: PPNN TMEEA(MWHMEM DST if ’L’ 3) _2zpe A Cell T2. (psi) (psi)’(psi) (psi) (psi) (p81) SE ‘(pai) (psi) (psi) (psi) 5 II max Load Dgpsi 'qu; (p81) (gm/CC) (1081) (psi) mommwemw ONMfi'b-(now- F NNP-Nd‘Ofi'O OOOPPNNM mmmmmmmm OOFPFNMM mNNO‘WO‘Vfi' 00...... P¢h0mmwm v-v-v-NN ¢mwowmmw o o o O O O 0 o OVMF‘K‘MVIA meomv-xo PP (‘CO PMNP’OW O PMQ‘WFO‘S wmv-OU‘NO‘O" Q PNMMVG’M mNmNPOQ¢ . .00... O PPNMfl’fi'Lfi mmOPNOm¢ OFNNNQ’Q'M PMONOMU‘N N¢©®ON¢P 91-1-1- \omfif-POQP' mv-IDMFKO ON PPNMG’ Nmm¢¢®0M EE$EH O‘d-mkod'OO O O O O O O O FomNMb-O PN\OF\OP PPN co fl'O‘l‘WO Q‘M ONMth-m" P mfi’fl'Mfi'O‘M PNMQU‘WI‘ \OV’MPMOMO QPNMVG'M MCONQPNO .0... PNd'd'mbzw. NMNNPWN MQONMQO FPFN kaOI-MOO O O I O O PWNMMQ'N PNMID‘O bmmbmmm FNIh‘OQO“ Pv- mOOPPNN FNNNNNN . Q Q 0 O O O PPNNMGMW M0 O‘N “‘6': F'N NNNMONO‘ Pmmb-ONM PP!— 01"”um QOOOOOO s-(nmoomom 0...... OPNNMMW NMKDWMPK“ N\OC\DN\O® FPNNN P‘VG'PN O‘d‘ 0‘. o o o o o FPOlflwl‘Q v-mbmcov- PPN b—bmcoomox ONfi'kOO‘OP Pv- bmxmn0t~l~ 0 PN "“0an Nmommmv PN «mad-mic NMOMQ’MM PNMQ‘U‘WK“ va-mmaxco «(moo-now word-0PM OMIDOO\O FMQIA \OMK‘Q'PKDN PMQWOQO‘P F #mQOF’N PPPNNNN 0.00000 PPPPPPP NPNNMd’IfiW o o o o o o o MWO‘NU‘Q" m PPPN a: TABLE A (CONTINUED) 6 DST “Zn-‘1 ’(p81) (p81) (psi) (psi) e A Cell :: Bulk Load Dena (psi) (gm/be) (psi) (p81) “£3 (psi) (psi)‘(psi) (p81) (p81) (psi) QPVPQKVO 0...... Omvmb-mi- P v-vxombmox OOOOOF" QMQPF‘DW OPNQ'QIAO Pmmmfl'MN o a o o o o o P‘OO‘NQOU‘ \Ofi-mmffifl'l“ OOOGmO‘F PNMW ONO F QQNWMON ON #40503“ P O‘F'IOKDNMO‘ QFNMIAUHA 0000000 PPPPPPP PNNMd’InKO mmmmcov- v-FPN 159 aocomaomoov- OMKOQONS'P PF!- NNOMOO" 090?.00" \DQ’PQOQIA O’NNQ'Q'tn PMMMW [‘N O O O O O O O thbomm PFNNN \OwQPQF’M O O 0 O O O O ouwraomxocn F¢COP®N PPN aooommmwm ON‘WOQO“ F'- PFMMMNO F'N m¢ml~l~ \OPNOPPO‘ 0 FN rand-tn MMPNMNO PN Mfi’mml‘ PO‘CDKHO'G'O‘ concoi-d'aom 1-1-1-1- Nrmnmv-OO) o o e o o e o v-mNr-lnoo v-NNflOKO d-I-NNMQ'K‘Q MWC‘NMCO" 0 PPPN NWMNOK‘O 0...... FNfl’komFM 1-1- NNmeFWO QQOOOF" moor-wwoax OPNMd'Inln NOPNQPG NMQMQ’I‘: Pv-NN mmmo>~oo O O O O O O O FWDOVGPPQ' run-(macs PP wNQQO‘Pl‘ ONMIAK‘O" PP FMMMFOMO OFNnfid's-Hn ONOCOO‘OQ PN MMVWOW PMN #Wlfifi" .00.... PNMQ‘U‘mP Mmmmo r-o N “‘50me FFFP MONGOQ'PO‘ ONWMOOO‘ PNMM mentioned-(- PM¢\DI~.O\O P MPO‘OFV’N PPPNNNN goo-coo PPPPPPP mv-NNMfi'lnm Mk0 0N Inw" PN TABLE 11(CONTINUED) I: r 6 DST 'TEZET"iEEIISEEIIIEEIIIIEEEIIIZEEét. (psi) (psiJ‘(psi) (psi) (psi) (psi) e A Cell Bulk Load Densit T (psi) (gm/be) (psi) (psi)‘(psi) (psi) (psi) (psi 3 TEST Reg1 1 NPNPFPP FM‘OQNNN} PFP v-Lnb-Flntom OOPNNMQ' \OQFNMO‘M O PMV'MIOQ V‘QFMPOM o o o e o o o mt~¢mmmo PPNNM N N Md’NQIO "1000\me *QI‘QO‘ Pia-v- MVMQU‘N d’ PMWQPQ" v-v-c- PNNIfiONQ" PMVQ P’QO‘ CWMF’MQIOO‘ OPNNMVI“ C‘Q O'\\O PMQ o PNMV’IGQ thmefiN o o o o o o ML‘PVQPV’ PFC-NO) hmoommm o o e o O O 0 PNIfifi'V’PIfi PNQ'IOQO \O \O d-mcmnm PmeQON F1- O‘VQP’PQQ OFPPFPP o o O O O 0 ‘ q-v-s-v-v-PP PO] .000 \O O‘NIfiQ" v-v-PN mnemm' 160 mePN>¢ irwunmuauun Pv-v- Ob-mmoxom OOOOFON \OIDPQOII‘O OPMd-IOPO‘ Mbb-PMPF 0...... ~u~rw~vwoa\ FPNNN NIn MOPMOIA md-Q'PNMM FMth-O‘ Pv-v- QMNIO Qd'ln v-rmnb-mv-m 1-1- NQQPPOQ' PNMMQQQ \OMMPOQU‘ OPNMQ¢Q {-meth Ps-de’ml‘: ONIOONFQN NIOOMIOOQ PPFNN o o o O O O 0 PQI‘NPIOO‘ Pmfl'l‘Q NOb-FOPN NQ'IAQNNM v-v-v- “\IO‘OONQQ QQO‘MMFN OPNVMPQ O‘QOMNPP 0...... MQMQIOQO FFNNM OQIfiIfiMIfiC o o o o o o e “\QO'I‘OCQO MFI‘QC VPQMMIOO 1"me Fwd- PF!- mbbwbbm FNV’MIOP'Q PIOIDIO PQQ o 9010')?an PQP-FQ moo o FNMV’U‘Q OJF1DNH-0HD O O O. O. O nab-FIACDPV PPFNN OOH‘OOIQN NOQMO‘GSO‘ PNVMD‘O‘ Ihd'P‘IhNOIn .00.... PMDI‘O‘FN Pv- NMK‘PQ FPFFP O O O O O O P o FFPFFF‘ 1.08 thNMd’mQ OVAKOO‘N IDQ F FFN TABLEJA (CONTINUED) 6 DST ’V33"iEZZII:IEEZIIJEEIIZEEEZIIZEEEt eACflJ Bulk Load Deneit -:_ r (p81) (em/be) (psi) (pai)‘(p81) (psi) (psi) (P81) (psi) (p81)’(pai) (psi) (p81) (psi) PPFNV’NN o cc 0000 Fwd-IDO‘IFN P‘- MOMPPQP C'DONNNMV MFNMI‘OQ ONMV'IAFQ r~¢u33 A PF ¢wmt~hl~ I" MU‘W‘OPP #IDKO Q P M: @ (3000000 0000000 0000000 a 00000.. 0090000 0000000 an & PPPPr-v-r- PFC-FPv-P FPPFPPP 3 V INmPNNM¢mQ Prmmm¢mw NPNNm¢mm I'd-fl 00000.. 00.0000 00000. (d m mxommmcov- mmmmmcov- mmxomwmcov- 0 p. 0 rugby-N v-v-PN PPFN '4 V II" (I: a: €59? (p81) (psi)‘(p81) (psi) (p81) (p81) 6 DST 033g ¢QQL e A Cell T E51. (psi) (gm/5c) (p81) (p817‘(psi) (psi) (psi) (psi) Bulk Load Density vmmmmww PN V‘Ol‘mo P NEQPI‘O‘IO 00'2Nmfl'ln VNMO‘d’LfiQ OPNNVIAKO 000N¢PQ . . . . . . . MQF‘MQMM PPPNN MMVS'FQK‘N . . . . . . . NOOF’QIOO‘ PMIAKOON NQNO‘QPI“ PNInIDQFN v-r- M6 ONQMQNON Pm¢m®00 Pv- VMQ‘d’U‘MQ COOPPNQ’ (no I00 (”(0% OFNMMVM “\PFOOQQ N\OO¢O\N\O PFPNN ##MMMO‘Q’ ....... FPmb-Pmd' PNVO‘NID P1— FOVPPQN PNV’QQO‘N P \OOONMIhm ONMVMQI‘ (Univ-0000 Ov-Nrfid'lnm QOOQQQO ommm'd-LOP OMOMIDOO NMQFV'Q" PPPN mews-mom *PNNMd'mm Mk0 O‘N moo F F'N MOON-0d"- ....... wmmbmmw PFNKOInO'IID 00000PN FFNOQIhm ....... NNMV’Q‘MQ IAOMOQQQQ ....... NMOd’bo-d' FPFNN l‘N moo IOVCI ....... PONQQ'O Q NInQ NQb-d'b-VQ' "N #QI‘O‘P P QmQO‘Ql‘Q OFNM'd’lnkO \ON *NO‘P—O‘ OPNMMVM QQQNQQO 01"Nd'mww N000IOP¢ NIhQPMQO‘ QQ'QNNPM . 0 O O O l O od-mkakOM PNMU‘ QMQ O\N moo P PFPN 6DM3 e A Cell .Ruk Load Density a” ”f (P81) (psi)’(pai) (psi) (p81) (psi) (p81) (gm/6c) (psi) (pai)‘(psi) (P81) (psi) (psi) TEST 17 NOMOMAQO NQWOQO "M em - .0 Omar-O“- P o o o o 0 memm QOI‘NO‘ION ONNd'IfimQ Od'd'l‘NO" ¢m¢m¢bw PPNNM OMQOWNQI“ o 0.0 o o o o mmmmv-ov- Pd'mMIOO Fv-N IANMQ O “\Q P‘HOCOFN‘I' PMd’d’d’O‘l" 9010'}?me mmhhmmw OPNMU‘QI“ OOQI‘N moo v-NNMIAQP' PQQU‘OMN 0...... mxomonooov- PPFN \ONd’O‘O‘d’P Pb-LOIBQKOO PNMd’Q W7 ONOV‘GOV'G' N‘d‘tfib-CDON P!- N MIGQ MM" 0' PNMQ’IAIO mPFPPhb ONNVMQI‘ QI‘N MMPO MO‘Q’QNW‘: FF'NNM NQOIDNON . . . . . . . d’PlfiQOIfiM NVQOMO‘ lnd’lnP-QPO‘ Pd’IOQONVP NO‘PMPNM ....... FNfl'mKOl‘P Q00 FNI‘N 0N Md'anQ ov-NNMOm PNMQIDFQ N‘sNQMPQ . . . . . . . Mbv—VI‘FN PPPNN (nanor40F4~ .O..... POPQQPm PNMVKOQ NPNNMfl'm‘O Mk0 0‘0! (hoov- v-v-v-N FPQ’PIOOQ N‘d’lfiPQON P1- MPQQQ PM ....... 0PPNM¢¢ Ch PQ d’O‘IfiN 0 (“'3'“)ng \O MQO‘OPm AGNQPQ'O‘ PPNNN «suns-morn- < . . . . . . d-QPMQWé meb-OP FF MIDVI'P'MIDL" Fwd-\OQPNd' PPF’ 0 VPQQI‘M 1- NMMV’IAKO Q mmomom 0 PN d-tnbco QV‘OFQOQ 0 N Mfl'lfil‘Q QQPIGOMQ (moon-(moo PFC-N #NQQfi'OQ PFNQO‘MN Ps-Nd-ln MPNNMG'MU) 0...... QM'HOO‘NII‘Q" g PFC-N b DST Ins A can 0:... aux Load Density (p81) (Em/cc) (psi) (psi (psi) (psi OVPGHAOUfiF- andWOOHDHN Pv- \OI‘N QWDVM 0' ONMMMM CHDOND¢H3N1 0WVOH¢UHPGD FO‘O‘V’O FWD C> P 1NF¢H3¢HV<¢~ ........ CPI-mammot- \ONOOWOFMO‘ OPNNMQ'V’Q' d'QNNNNIDM OOPNMQMIO comd-(nomom OFNI‘Wfl'InQQ IANNONMIDO '- MU‘Q 0‘01 #40 MIAMMQ #QO" OP¢mommo PPNM O‘Q O‘Q MML‘Q OPNV'MPQO‘ -oww n \ V VJI-L LJ‘UUU I Bulk k Load Density K 11' 6 DST e A Cell (P31) (gm/Ce) (psi) (psi)”(p81) (p81) (psi) (psi) (psi) (psi)‘(psi) (psi) (psi) (psi) \OFFfi'QMmO ........ 0"’(\H"\'0N¢0 MMQNNQF’O‘ 0 Fd’MIDNMI‘ PN Mfl'm MPPMIOP-QO 0 FNMd’flNIOQ finchmmwm OPNNMV'Q'U‘ V'OMFQNO‘O‘ OPFNNMM¢ \OlnN MOQQQ OPNMd'd'U‘Q l‘lnlhIBOQIO O‘ PMth‘OPQIn v-v-v-v- MQPMO‘MOP o o o a o o o o OPQ'QVPQV F’NNF”) 169 QMfi'mMme OPNMIOKOFQ Md’MOOfi'O‘O 000000?"- ’ moo InO MMMN ........ 00FNNM MIK‘O‘PQQ VP A;Cell Vi“; if “E (fisi) (psi ‘ Type I? ii: (p81) (D81) (pailfiisi)w (p81) (gm/c0 Tpai) (psi muk Load Density TMflZO W2 mNmVPwFP ........ Nd'IAQONlnIn PFC-v- FIDFMQPVI’O‘) O'ONNMQ'MM \OIAV'O‘Q PVN 0""'NNQ'I.K\\£)I~ «moi-(mome- d’QMmMO‘MIn ‘- FN N MM MF’Q'PMMQV' o o o o o o o o PPQPOO‘I‘O‘ NMO‘MOK‘O‘ FNNN MFQ PQ cumin PMIfiQONfi'Ifi v-C-C-r- QI‘Q vmomm 0 PNMfi'InIDIO 000m0QNO PNMVIfi‘OPQ MN MQ I00 MIR PNMQ’U‘P‘QO‘ mmNMPI‘NQ . o o o o o o o Nmmi-MQQ“ PPPF’N bmmmuommm . o o o o o o o OMQQ'MNb-I‘ PNMMm mmmmPNNF v-MdWOQOFM 1-1-1- PPNNMd'ln‘Ot‘ (2mm O‘wa"? 0 FFPNN DMI‘I‘OQO‘Q Nfi'MI‘ONMV v-v-v-v- PmemQNN 00me¢mm hormm¢¢w ONNM'd'lnml‘ PFMNKOQOQ vmmcommmd- v-v-Ncumm PPNNP‘FOQ o o o o o o o o NV’PNOMI" "NNN MO‘O FWN mb PMQQOMV’M PFPF O‘CKO C‘s-(mam ONNMd'd'an NMMOOMF“ ".'NMU\\O PQO‘I Mbmmv-inoom PNMInQ P’QO‘ u-mmmwmbo MKOQNQWOO‘N PFPFN ("moment-ov- PNNVU‘ mm remind-In M030 FQ Pl‘ln NMIfiQQOOM bus-mucosa“- C'DOFNfi’fl’Ihln 0"” PMPO‘O‘m 0N Md’tfiQlfiQ QMOPQO‘VO MQMQPd'P‘N FFNNNM M0 MPI‘MO‘N mbbNéNOm Pmmmmvw PPN MQOQVNQN PMQFONMm PFC-v- O‘O‘OMKONOP- (OPMMV’IAQQ OMNthIhPM 1-N MVMQK‘Q “\NIOMONO 0': PMV'InQ 0‘0 0 1- '- QOMMPQFQ ....... «Nomi-«nomi- v-v-q-v-cu O‘PFWOQQP" . . . . . . . . OMOQ'NQQ" FPNNMU“ mwmmmvmmb o o o o o o o o AMKOONNIDQP‘I’ PPPNN a: DST - 6 11'; 3 1r. (psi) (psi)‘(psi) (psi) (psi) (psi) Bulk Load Density 0" gzpe A Cell FF_ ’1’“ 13:4 43.11; EEE-El. (psi) (gm/cc) (p 81) (pai)‘(psi) (psi) (psi) (p81) mcmo b-cn Pbm NMIDKOCDOOM PP!- Ffl’mb’om 0"" 0.0 "N d-d-an 0““ v-mbmcmn ONMfl'tfiW (“0 Como "\OO‘VO Mmmefl'l‘N PFNNNM nonbhmmm O “\PI‘N #01010 memm d-f" FPN M000 ‘1'qu PMKOP'ONMIA Pr-v-v- mmomxomor ..0...0. O PMMd'lnka ommmmmv-m 0 PNMd’lfikOl‘m mummomom PMd’LfiQC‘OO Pr- mommb-oo Pa) “mow-#00“- FPFFN o‘b-i-kowml‘" . Q C . O C . . m *NQCD" O Io-r-NNMID 173 O‘KDQMOV‘OO' memPMlfim 91-1-1- mv-mmmv-mv- . .0. 0 . . 0 0 CO "C "N I I I I I? N GWQQKDPV' OOPNM'd'InUD d'COOP-Mcnvf- MCMP’MQ Pd" FFNNMM NLfiQV’NLfiOO O C O C C C C O V’fi‘NO‘Olfid’F PLhO‘WOkOO FNNM O VPVO‘VQN 0 FNVWOQONG' moo mmmmw ONM‘d’Lfimm c-b-ovmnxoom PFNMVMWK} mhmo "MOO PNMlfikOI‘OW'O- «DCOO mo thin!“ Nmumb-ON PPPNN aunOOLnr-NO . . 0 0 0 . . . d'PV‘NFQV O PNMd‘lfil‘ hd-v-l‘tnv-coo Q 0 0 0 O 0 O. FMMWQOFM v-v-v- mmPNffifl'fi'm PPNNNNNN Q 0 O O O O O v-v-v-v-c-v-v-v- Kw-QHNflY¢UVOb- aruoounuwov~¢ m PPv-NN TEST 21 “\KO mm OPNV NMKOP' 0000 “‘00" ..0. OPFN MindWO FMWO‘ MOWOO‘ ONO‘N N P003" OFNV’ e A Cell T Rflk 6D$3 ff (psi) (psi)‘(psi) (psi) (psi) (psi) 1y” Ill: T’ 4|." bbmv 174 (psi) (gm/be) (psi) (psi)‘(psi) (psi) (psi) (psi) Load Density M .... YfiQN Qfiflfl TQTQ fififi OFNd’ OPMfl' 0PM? ov-mv PMKO NV m In 0000 00"": 000'- 0000 000 MOM!" lnPKOQ WO‘IhN “\NVO cmnm O O. .0.. O... O... .0. 0!:P1- Ov-Pv- GOV-N OFFN QPN \OQWO NFPO \ONFID MPFI‘ mmm O... .0.. O... O... ... v-mxoo Pfi-b-O F'd-l‘m vam tab-M F P '- PMQ‘M NlnNM \Dwtfi" mPfi‘l‘ Ml‘fi' . . . . C . C . C O C . . . C O . . . OMOM OWN-M OM01" O'd'ffim MIACD [~me P‘O‘Md’ meM FQON mom . .0 0... .0. 0... ... 0:03? 0Pm¢ OFMV’ OFM¢ Pmm (DVDNO \OMOF b-xomo find-m N wow 0 C C O O O O C O O O O O O C O N g g . OPNM OFNN OPNM OPNN E4 CNN 03 wrox-s-ow MOMO VOMDM mod-o E: man .0.. 0.. .00. .0.. ... kOMOl‘ momm \OPFIA anKOP magp- . C C . . . C O C C C . O . O . . OPNN Orv-N Orv-N Orv-N oq-N ov-cooo (‘WOlnd‘ O'H'LON QO‘NCO FO‘O ... 0.. 0... ... ... Nut-ml~ Pmmb «Pd-moo gmxob- N¢g~ mem MMMN PFQN \OO‘MN FMd‘ ... ... 00.. .... .0. ommo owmm on»: ONPg o¢w OFPP mmwm comm mmwm th .... I... O... .00. 0.. Fde' OFNM PNMd’ OPMfi' r-cum ...“nm PMMKD PMd'ln Pond-In (“fl-Ln CO 9999 9999 9999 99.. 999 PFFF PPs-r- 1-1-1-1- 1-1-1-1- Pg...- NM 99999 “9999 *9999 “99.. F999 mama om: Mk0 Chm Mk0 mm ammo m Bulk Load Density T12? A Cell 02p (psi) (psi p817 (psi) (gm7bc) (P813 (psi ‘ Fwd' PM!) PPM O C 0 OOO Pfl'M ... PPM «unv- MP‘M P 000 oreux r~¢ d-om PMLO (00¢ OPN \OMP OPN OO‘O‘ ... PPN 00M FMKO FNQ .OOO 03M!- 0"!“ \omm ... Nw~fis F MVLfi enuv¢ ewe anl" FMLfi O‘kOM OFN VNO . C C OPN ova-co OPN PMt" Ndwo 175 \OLGM PM“) (MCI)!~ 000 wd'd) OWN mace MPM F FNM mmxo Pd’ v-rmn (noun OWN m0 OFN O‘V'CO OPN FVIWO 0mm OOO \OVKO OPN vwoux ... MGM F MON 0.. MNQ Nd‘ MFln PMLh I‘m?- OPN (Dd-Ln ... OWN 00“ O O O q-q-m TEST 23 xoxom PMlh NMQ OOO ONM M‘Oh Ml‘N P CONln owed) run ux<¢~ ... PMln COO PNM bund- FMM filnfi' 9.5.: QM? ONM PPN O O O MP'N F run") 0 0 0 MP”) PM NMP ‘-~nn O‘Qlfi OFN 00“ . PNM 0PM . FNM Vir V” 6 DST VSL. SHE (psi) (psi) (p81) (psi) (psi) (psi) guy e A Cell- 3% Bulk (psi) (gm/be) (psi) (psi)‘(psi) (psi) (psi) (psi) VLoad Density \omm v-omn PNN 00“ [POM- 0PM NPP .0. MEN F bmm NNM PM MPl-n "Mm PPN O O O T‘NM 0®E . O O PPN MNKD PNM POP MKOO‘ our FMm MEN OPN Pvt- “NM \000 mmm P QMKO Quad) run Ed'ln O O O PV'kO QV'N ,OPN OMN "NM PMM PNM mom 0 . . NLfiE TM E\ON v-nmn NVWO 9°" math 0 0 . 0PM ”“00 MEN F NNCD MVO PM Q'ME . 0 O Pmm 0‘0“) ..0 PPN O‘Eln 0"N cocom O O 0 PNV’ Ch'd'0 wa 0mm 0 O O PME TEST 24 O‘MLAKOM ONVWOG) P¢mwm (.300PP lnEMO\0 ... OOFNfl' CDC‘QNP u-vs-owroo PP oommd-v- 0\Olr\00 NMCO COOOFO" ONVKOE OMO ECDO‘ 0N OWNd’fi‘ Nd‘E ®0MP0 .0... ON'dWOm W7 0E0®M v-meooo NPNQE Cu"??°" QNNPO OPNM<~ CONEd'M Pmmd-oo PP vflDbflDF‘ 000.0 V-PWOflv- Nmoo mePO ONMWQ PMCD d'Ln PNMd'ln Q'CDOCDM O‘ENNE ONInEQ Nww¢m 0000‘- #000!“ OPPNM OMNO‘CD NIDOV’Q) ONCOOWKO PC0000 M\OO\ mmmmm 0 0 0 O O FNmmE TEST 25 \OmmFE F¢EFM 1"" FNNO" 00000 O‘d;E00 ON (dune (\IU‘O‘MV . . 0 0 0 MO‘mNE PNN OMNME O O O mmmmm Nmmo FN MmKOPN P0000“: P TABLE A (CONTINUED) e A Cell T Bulk Load Density ‘(psi> (psi) (psi) (psi)' 1'; ii a .V’,’ (psi) (psi) f1 1) (psi) (psi) (psi) (Psi) (psi) (gm/be) (psi) (p8 Efl'KONK) «whwm PP NNOO“ 0.0.000 NCDCDNQ) PNMLRLB N\O"'|.f\¢ MQMNE PNN 00(3me 0 O O O O NOV-(OE PKOMO FN VEMN '- PMOO‘P P NMfi'CDC‘ PNMd’Lfi N V‘MECD O O O O O PNMfl'Lfi Nd'mCNN . O 0 0 . PNMVWO KOOMV'E ..0.. mro¢h umMd' W8 OQLnONN O O O '0 . N¢©P¢ PP NMUNF'KO ..... 000 III O‘ME\O\O ONNfi'Lfi oomxooom 0 . 0 0 . MC‘WNE PNN POGEM O O O O O d'mFlnd' Noomcv F‘N moo MQO P'mxooov- P ONPd'd' PNm¢m ()0me O C O O O PNMfi'm Fw¢m¢ waF'd' PP NNFN“ O O O O 0 00000 I I I M\DM'<9'E .... PNMfi'U“ OPEPE ¢O\OM® PPNN \OOOEm . . . Q'CDQM“: NElnM V'N ENkOMfi' Pvmmw Funk-Od- PNNMKD r:m¢om ‘-.N thn MMMVI'M waFd’ PP KOOPM‘. 0'0000 \ommoo FNMMW OWENW . . . . . ¢O\O”\® FFNN manna“- . . 0 . 0 K‘Ob'mw MEV‘N V'N [:‘MQMU‘ PdWOO‘P P 0NIhEO" FtNMfi‘m ONNKOE O O O PNm-d-In TABLE A (CONTINUED) Dfl aux Load Density »(p31) (ps1) (psi) (psi) (psi) (psi (Psi) (gm/Be) (psi) (psi) (psi) (psi) (psi) (pail? Tfifl26 OMGOWd' ounces—<1- PP MMKOKOM 0000" OMd'mKO ' 0 O C O O "NMQ‘KO ENLfiLfiN ‘00... MPCDVO FPNM PEum 0 0 I O 0 d-MNNKO mmmm PN LDAOMOE ~¢hom PP 00000 Nfl'mECD d-OOOtnm PN¢m> W9 NMU‘NME waFd' PP N‘DMCOO‘ OOPPP bmvrb 0"NMtn \OFNfi'N O O C O O ¢FQ¢P PFNM \ooomov- mmmoom moomln F'N cos-moo: F'd-EON PP M\OE0"' FNMLhKO d-OHnOLn .. ... PN'd'HDE KONGJNLh Pmmmb OOOOOMO .. ... q-cor-an PPP *d'fi'mlnd' NInQPM PP NMNfi'N 00FFN MOPEE ..0.. thNNNM \omv-v-o O O O O VFONQ‘O FPNN EPC‘LGN 0 O O O O \Dd-PkOE MOKDN PFN EKO LAME P¢>mv P *0 FQN PMfl'LfiE FN Pad- 0 O O O C FNMMm QLOMOM PMLhECD wh¢¢w MQV‘LnO‘ PPP 00¢®® O O C O Nowmm Frmm NEKOQN cud-mac'- P (mot-boo 00000 MFNNMQ QMQ ONNID a) PP QMFON PMC‘PV’ PP MEfl'NN 00"PN OEMOCO T'N mmm «JNQFWD O O O O O MPONIAO PPNM #NMPN 0 . . . . MFO‘V'Q MONKDM PN EO‘N VON «no-coca: PP 1) (psi) (psi) (psi) 6 DST (psi) (psi ‘(ps TABLE A (CONTINUED) fiiLfi e A Cell WE (psi) (psi) (psi) (psi) 2'. 4 (psi) (gm/be) (psi) (psi) 1 Bulk Load Density \OOQOO PmmPfl- PP VEN\O.M 0.. 0000': N MMLhO‘ FPN¢m \Okomd'd' O O O O O MOEVO PPNM mmlfiE" . . . . . NONNm MC‘kOV' FN ENwth fwd-K0001 P TEST 27 DNEO‘O O 0 O O O OPPPm q-xoq-Pv- OOFNN OLGNNE "wao F NMN\00 00PNM mmmwrm 0PNM¢ EmPE'd' v-e-mmoo PP O‘MNNM OQEQQ NKO EONd'CDKO 0PM¢\O \OFO‘mN QPPPM MEQOO‘ 000N“ \DMQ moo QPPNM d-mmoow PN dunno NLhNfl'Lh PNMEm m m 0.5 5 5 -o -1 -1 -1 #O‘d'f'ln 00NM¢ CDCOONQ Pd'mmb- PP d-mooxom V'kOEkOln NMC‘ KOCDMOO O PMlnE «rout-moo OQPPN TABLE A (CONTINUED) 6 DST Type A Cell 0:. Bulk Load Density I'M 1) (psi) (psi) (psi) (psi)_7bei) (psi) (psi) (psi) (gm/be) (psi) (psi) (psi) (psi) (ps 181