" " a»: I ._.>‘ .V L ‘ ‘vrl‘: «3M 3‘" . ' / .~ .. . n23» “"’ .' 3‘ 1"?" .' LW. 15"»31341 "in 3 $53,;«hfi‘5-“W s; , «g, «. «My. . “3;: .tt'q "5‘: «51‘? ' t‘fl ‘_-.V:.e@:- . ‘ . I. 5‘. ._ "C: ‘ "“‘1' The Permafrost Problem A Thesis Submitted to The Faculty of MICHIGAN STATE COLLEGE of AGRICULTURAL AND APPLIED SCIENCE by S. G. R. Qe§tefano Candidate for the Degree of Bachelor of Science August 1948 “155‘s (2/ ' I? “/1 3.33 1 CONTENTS Pa ge INTRODUCTION DESCRIPTION, ORIGIN, AND EXTEI-IT. . . . . . . . . . . . . . . . . . . . . . . l TENPERAT’RE AND PERL'AFROS‘I'H..........................5 RELATION OF VEGE'IATION TO PERFAFROST. . . . . . . . . . . . . . . . . . '7 BEHAVIOR OF FROZEN GROUND..............,..............9 Action of Swelling.......«.......«....«............9 Soil Texture and Swelling...«...............«..,,.ll Action of Settling................................12 FORMATION OF ICINGS..................................l4 PERLWOST AND RmeTED ENGINEERDJG PROBLEIVZS. . . . . . . . . . 1? Dealing with Permafrost...........................l8 Building'Construction.............................19 Use of Pilings.......................«............23 Conclusions on Prevention of_Frost Heaying of Foundations............«..26 Road Construction...«..............«...........,«.27 Icing and Road Construction..................,....BO Bridge Construction...............,...,.........,.32 Construction of Airport Runways...................33 ENGmEERING PROBLEMS AND RELATED SURVEYS PermafrOSt surveyOOOOOO0.....00000000000000000000034 Planning a Permafrost Survey......................39 20802?) iii THE PRESENT AND FUTURE PERNLAFROST PROGRAM TIE ALASKA STORY. 0 O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O .44 CONCLUSIOIqS. O O O O 0 O 0 O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O 51 GLOSSARY.OOOOOOOOOOOOOOOOOOOO0.0.0.0000...0.0.00.0000000053 BIBLIquPHYOOOOOOOOO..00.00....0.0.0000....000000000000056 iv F OFLE TJOIUD The writer of this paper feels sincerely that this phenomena of nature, permafrost, is indeed one of the vital problems that the United State faces today. The present international situation makes the solving of this problem even more urgent one than one of merely being able to undertake construction in permafrost areas. With the threat of a possible third world conflict becoming more and more ominous every day, the importance of successful establishment of military installations in permafrost regions becomes the primary aim of all investigations of the problem. Actually, this is just the air that all experiments with permafrost have taken on. The U.S. Engineers, as you will read, of the St. Paul District Office, the Bureau of Public Roads, and the Air Transport Command of the Army Air Forces are conducting nearly all the tests being carried on. Construction for domestic pur- poses will of course benefit from the findings of these authorities, but to be sure their needs will undoubtedly be held in a much lesser light than those of the military. The following pages may not wholly convey this opinion, but then they contain facts which were established before the present world situation was fomented. Primarily, this paper consists of an accumulation of data from all available current and past publications dealing with permafrost. This data will give the reader some idea of the complexity of the problem and some of the measures being taken to cope with it. S.G.R. DeStefano vi INTRODUCTION DESCR N ORI IN & EXTENT Permafrost is, as the name implies, permanently frozen A ground. Soil subjected to this_condition has been frozen solidly for anywhere from two months to a thousand years. Most of this condition is located in the far reaches of land that extend well up into the Arctic Circle. Fully one-half of the U.S.S.R. has soil in this condition be»- neath it. On this continent the_permafrost line pushes as far south as the U.S.-Canadian border. in one place.- _ _ Referring to the map on the next page, it can be seen that the line forming the southern boundary of the permafrost region starts on the west coast of Alaska just above the region of the Aleutian Islands. It runs easterly from there roughly following the course of the Yukon River until it extends in a finger-like area to the U. S.-Canadian border. Running north again the line reaches and follows the 60th parallel to the 110th meridian where it swings . down around the south end of Hudson Bay. From that point it runs eastward to the coast and thence across the south end of Greenland to a point opposite Iceland. All told, this condition of permafrost underlies one-fifth of the world's total land area. .x.,.._; 53er aid 0";sz we 5.3.3.53 2% >3 75.2.3.5 .52: i as: a 2:9... . 828.231: ,. r21 85 no c _ of ON. ‘ x w ’« 1 III: 1 - Ll, l.‘ w 00 00 on 33523 55 0 33520.. SE: On 00 ON. 3. r0a Isl... . J .- .._......L......... a? .2. .. .9 .7555 1. I :0. iv 5.! '- ‘i .3 20.5.0” 50% fl&°F(U¢U: /../t\/| i J/KK «. fll ., c 2:233... 8.: 3+2 ooha 8.9. to _ nl‘ 111111 Q 40 44444 I 4 4 I 1 b «b‘ a 3:... :03 33 coo. «u _ i mien 453598 The actual existence off-permafrost is by, far the only concrete fact, known about it when people soughtto study the. reasonefor its grotesque behavior. , Facts that have been compiled, have been obtained through. thehard axiom, "experience is the best teacher“. In its unpredictable way, permafrost causes bridges to sag and collapses railroad tracks, roads, and airplane run- ways to heave, slump, and crumble; buildings develop structur- al defects, and land areas puff upward causing trees to. tilt at crazy angles. After a person has walked on“ this type’ofurww ground, small masses of water blisters have been known to form and burst with a report like a gun shot. A formal definition of. permafrost, would be,» f‘It— is a thickness of soil or. other superficial deposit, or, even bedrock, at a variable depth beneath the surface of the earth in which a ‘ tanperature below freezing. has existed continually for, a. long time (few months to thousands of years). It is defined exclu- sively on. the basis of temperature, irrespective of texture, ' induration, water content, and soil type composition". This would mean that to, exist at a- temperature below freezing . permafrost must have. logically originated when a temperature of 0 deg» C-. estates.- L. 1*» 1.8: therefore. .now. a 90mm. feet that most Perseus interests? as??? that Pawns?» first. appeared during the PleistoceneormIceAge. By~ referring.- once more to the map on the preceding page, itcan be noted; just to what extent the Ice Age affected the northern half of. the world. The theory has been offered that the existing area of permafrost, is smaller than that covered by the glaciers of the Ice Age because of the fluctuation in climatic condi-“ tions that have affected that area since the recession of the glaciers. As for the thickness of the permafrost, it has been noted that in some areas bordering the Arctic Ocean permanently frozen ground exists at some 900 feet below the surface. Covering the permafrost is a layer of soil that thaws in the. smaller and freezes in the winter. Because this layer freezes seasonally, it is referred to as the "active layer". The thickness of the active layer varies with the soil composition and the vegetation that covers it. Surface exposure and snow cover are two other items that affect the thickness of. the active layer. For example, with a good insulation covering. . such as ground covered withpeat or snow, the summer. thaw can: not penetrate to a great depth, therefore, the frozen condition of the ground is preserved. Thepermafrost table in this case tends to rise, under the insulation reducing the magnitude of the active layer. In an area. devoid of much vegetation and. insulating matter where the ground is exposed, sunshine will thaw the ground to a much geater depth. .In this case, the ; permafrost table. is lower thereby increasing the magnitude of , the active layer. Thus it can be said that an insulating cover is essential for preserving the frozen condition of the ground. Fig. A illustrates the various types of soil conditions that ]_ Paw ZONE * RCTIVE zone \/< IDEUTICRL. 1 Pavemeecs-rL NPERMF==F=TEDST Tasha mac‘s-Zeus EXTEUDS TD $2?“wa Face-r Zoua '1: }ncma zoue a “ass“ \\ s ‘ . g :3 m » “\\\\\\\“‘ A PEEMQW ‘ --r / ICE LEUS ‘IIIIV ‘ CZOWUUQJS 9521-4wa WITH GROUND ICE 'Wzoua‘t }=acnv= zoue wszcz raw/V ”rm amount: “\\\\\\\\\“‘ o: :1 DOEYI ISLQUDS O: PEIZMQFTZCET' ILJ UHFTZOZE'N GROUND 2:23:1- ncrnve zone. ‘I 97“ mam/ac: an: W“‘I|‘ ““‘ ‘l Graouuo ‘ ‘ . < “‘ fl“" umzozeu . ‘\‘ - fl‘ 6WD ' \‘§~’ _ LWED memos-r exist in the presence of permafrost. The top example shows; the condition Where the Frost Zone (that portion of the soil that is subject to the action of frost) extends all the way'., to the permafrost table Which is the upper limit of the permae frost. The next example Shows where the active layer consists of the frost zone and a layer of thawed ground. The thawed- ground results from the fact that insufficient penetration of frost did not allow the frost zone to extend to thepermafrost table. Also Shown are veins and lenses of ice existing in the permafrost. In most cases this ice was formed in the formation of the permafrost and has remained in the same frozen condition as long as the permafrost existed. The third section of_soil shows another condition that sometimes exists.- Below the usual layers of the active zone, the permafrost is present in iso- lated "islands" or "kidneys". These islands are surrounded. _ by unfrozen ground Which has escaped the action of frost._The last example Shows a combination of all the conditions Which can and do exist in the same area. W As stated in the definition of permafrost, temperature iswhat permafrost is defined by exclusively. Therefore, knowledge of , the existence and distribution of various temperatursconditione in the ground is essential for those who intend to have anything to do with that soil condition in a construction way. The L ‘ control of these conditions is primarily a climatoligical problem. Basically, this problem is divided into two groups of factors, Constant and Variable: Constant: 3 7 a ‘ 1. Geographic position (latitude, exposure to . Bun,.et¢:> 2. Temperature of air 3, Cloudiness 4. Precipitation 5. Direction of prevailing winds Variable: 1. Snow cover 2, Vegetation~ 3. Moisture content of the g‘ound 4. Heat conductivityof the ground 5. Surface evaporation The constant group more or less stabilizes local climatic_con- ditions. They might also be used after a proper amount of Study to formulate building specifications. The second group, UN HEQTED BUILDNG + HORN-I l ' m/ » ragga/W \ // /' / / / ’ ’_ 1/\N Hera-rec: ’ -" \xg/ NEW PIP-'1' 'TRBLE ECHO FILL. new :=.=: V “L! /.——-K\ / \ OLD PF? 'TfiBLE Eur-‘3 variable, to some extent can be controlled by man and can be employed to change the thermal balance of the ground in a desired direction. Buildings and earth fills in the permafrost area, tend to alter the existing temperature distribution or thermal regi- mem of the ground causing the permfrost table to change its p osition. Figure B (Tsytovich and Sumgin) show how the permafrost table is altered by the existence of buildings and earth fills. The top illustration shows, how the insulating effect of the building has raised the permafrost table. It is higher on, the north side of the building because of the thawing effect ofthe sun on the~ south side. When the structure is heated, shown in the second illustration, the radiating heat thaws _ the active layer and lowers the permafrost table. The effect of the sunshine also helps to lower the table on the south side while again on the north side shielded from the san- light the permafrost rises above the normal level. The bottom illustration shows the effect of earth fills. If the fill» is made of ground containing a certain amount of, stored heat, the permafrost table will sag at first. Gradially with the dissi- pation of this heat, the level of the permafrost rises up in? to the fill as far as exposed area of the fill will allow it. EELATIQN QF VEGETATIQN TO PERMAFROST One method, after much study, that is used to indicate the, presence and extent of permafrost is to study the Characters 1‘ istic vegetation that is prevelant in areas where permafrost .1 exists. For example, the presence of treeless peat bogs north 3 of the 64th parallel and is in most cases an indication of the ; existence of Shallow permafrost. ‘As for grassy vegetation,_ there seems to be no difference in that overlying permafrost and that Where permafrost is absent. A large group of pine trees or similar type of tree with promi- nent tap roots could.be a very good indication that permafrost is absent. If it were present it could be at a very great depth. Larch and spruce are two types of trees that manage to exist no matter what the-depth of permafrost is. Althougu the larch has a tap root which in most cases is killed by the rising level of permafrost, it has an ability which allows it to survive. It is the larch's ability to form.a new system of’roots at a higher level after the lower system has been destroyed which allows it to exist in areas of shallow perma- frost. .As for the spruce, it naturally has a very Shallow system of roots and has been.known to grow in areas Where the permafrost is only a foot to a foot and.a half. Fir trees are in the same class as pines When it comes to indicating permafrost. It is either non-existent or present 7 F at a very great depth. vThe presence of small, stunted.birches is a pretty good indication the permafrost is close to the surface. Willow groves generally indicate the absence of permafrost. gmva ENGRI Two of the basic deforming actions that ground undergoes are swelling and settling. A ti n Swe Swelling is the volumetric change in the ground with forces pushing vertically and horizontally on anything that is on or in that affected area of ground. There is no limit to the area that may be affected by the action of swelling. It may vary from an area of a few square meters to one several hundred square meters in area. Records show where ground has swollen or puffed an area three fourths of a mile in perimeter to a height of 300 feet. It is this action of swelling when it is not uniform that causes damage to roads and buildings. This non-uniformity in swelling is referred to as "differential swelling or heaving". Through tests and observations the causes of swelling is plac- ed in four classes: 1. Hydrostatic pressure of yound water. 2. Increase in volume when water is converted to ice. 3. Force of crystallization of ice. 4. Any combination of the above three. An example of the action of hydrostatic pressure is shown in Fig. C. The top illustration shows the ground water percol- ating through the unfrozen active layer of wound above the % //////T///77 #mnms W//// JJ __J /////////////////// FOWD‘T‘I ION c: I: =Izos-1- BLASTEZ EFTZOST MOUHD oz PIuecfl FROZEN H“ lllLllUl «.wmp II IIIIIII DEZMPFZOST‘ /////////////////// // Emmet/aw Rag-=51— ’l /% //// //////// % permafrost table. The second illustration shows the active layer partially frozen on the left and frozen directly to the permafrost table on the right. The ground water continues to percolate through the unfrozen soil from the right, but finds it cannot go beyond the point where the frozen active layer and permafrost come together. Because the water cannot con-j time on to the right or percolate down into the impervious I permafrost, it begins to exert an upward force as more wateri comes from the left. The pressure created forces up frozen ‘ active layer. The pressure forces the trees out of their vertical position into various oblique positions. This con- . dition is effectively referred to as a "drunxen forrest". The last illustration shows what happens eventually if the pressure continues. The active layer being frozen can take very little tension stress, so, therefore, rupttu‘rc'es. The ground water under pressure gushes up and out ofAbreak. The water freezes almost immediately from the sub-zero temperature of the atmosphere and a large ice mound is formed. Upon freez- ing the ice mound creates the same conditions as before the rupture of the ground by sealing the break. The pressure beneath it can be relieved by puncturing the ice with some heavy sharp instrument. The term ice mound or icing will be used to a great extent in this paper to describe a condition resulting from the presence of permafrost. Icing is the term applied to areas or mounds of ice formed by the freezing of successive sheets of water 10 which may issue from the ground or a fissare in river ice. §911 Texture Q Swelling Texture of the soil is another important factor to be con- sidered when considering the action of swelling. According to texture, the soil can be grouped into three classes: Ground that does not swell: 1. Solid bedrock 2. Ground composed of coarse fragments (pebbles and boulders) with the _ . interstices filled with analler frag- ments of the same material. Ground that swell little: , _ l. Gravel and coarse sand with the admixture of fine particles (clay or silt), moist or saturated with water but without avail- able supply of additional water. Ground that swell a large amount: . l. Gravel and sand mixed with clay and silt, moist or saturated with water and with access to additional supply of water. 2. Sandy clay, clayey sand, and clay. . 3. Fine sand, sandy silt, silt, and wet mud. 4. Peat. ‘ (2 and 3 of the third group are most liable ll to swelling, especially when saturated with water). Ati fStt The action of settling or caving of the ground can be just as destructive as that of swelling. The most common condition that causes a noticeable settling of the ground is due to the melting of ice wedges, veins, or lenses close to the surface of the ground. This is caused by the thaw reaching these areas of ice near the surface. than the ground is of fine enough texture and is subjected to ex- cessive wetting by rain or melting snow in the course of being thawed, it will form a mud-like material of paste consistency which is referred to as "slud". With this type of ground beneath a building during a thaw, the ground will literally "ooze" out from under the building causing it to settle. Settling also has several factors on which it depends. 1. Composition of the ground 2. Amount of ground ice 3. Depth of seasonal thaw 4. Other factors which affect the normal depth of seasonal thaw One factor that affects the normal depth of seasonal thaw is heat radiating from a building. If there is a miscalculation 12 as to the amount of heat transfer from the structure to the underlying ground, a condition as shown in Fig. D. could be the result. Without the proper insulation, the heat trans~ mitted to the ground.may lower the permafrost table below the lower extremities of the foundation and deprive it of a good bearing surface. The thawed ground will most likely not be able to take theidownward force of the foundation, and settling will be the result. 13 m ,\/ INSULRTED imam-G hit‘tflV TESL—E. . \_<:>I.c> as. 7 ~04. IK’SULQTED w” « “of matey ~ \\ Hing-e \\‘ \‘\\\\ \\\\\\ was“ I nouufimmokl 4/\~ A ///////// ’ V/flfl # 5/ \\\\ \\ \‘ \\\ \\\\ \\\ =6UHD=ITIOU \\\\:\\\\ '// ua-PEVTRELE J FfiGi D . FQRMATION OF ICINGS Icing was defined earlier as a mass of ice formed during the winter by successive freezing of sheets of water on top of each other. The water may seep from a river iced over or directly from the ground. Fiver icing is formed When a shallow portion of the river-is 5 frozen completely to the bottom impeding the flow of the water downstream. Hydrostatic pressure is formed and the water ._ breaks through the over-crust of ice some distance upstream. The water seeps or flows down from the fissure over the first formed ice and eventually freezes there. This process is re: peated.many times and usually results in the icing condition covering a very great portion of the flood plain of the river. This type of icing is very destructive to bridges and roads that cross or run near the course of the river. Fig. E shows one type oficing that has occurred beneath heat- ed structures in the permafrost area. The heat from the structure radiates into the active layer under the structure and thaws the active layer there. water flowing through the unfrozen portion of the active layer above the permafrost forces its way up through the thawed portion of the active _ layer under the action of hydrostatic pressure. This is very _ similar to the principle upon which an artesian well operates. The water forces its way up through the floor and out the door- ways and windows While in the process of freezing. At times 14 NWxfiD LIWONh EXNMQ \\\\ \\ 4 a theta X/K fl 2333:»? .52 $25 \/\ \IIIIIII'III/ manna. uOLNanu Glfian. umoza dull... I “u all \ dwfljxguuwofit? \U“?”"“‘ IDER no 7.0..ruw 82:“??? ‘7‘ — . ”5982.21 * 80 L50 02a NOQE 1930812. 05 NEE/2+ MO. mggfim NMOZD wanj M25". .uO @237EILI roofs‘have been lifted off the walls. The water, of course, freezes solidly and leaves the structure in the state of huge ice cube with wooden sides. Some of the conditions that are conducive to the formation of icings are: 1. An insulating mat of moss, vegetal debris, down timber, etc. 2. Presence of ground water in the active layer. 3. Low temperature of the air and.only thin cover of snow during the early part of'the winter (December, January) . 4. Proximity of the permafrost table to the surface of the ground“ . 5. Thick cover of snow during the latter part of the winter. The thick matting of moss and vegetal debris insulates the active layer beneath it and prevents it from freezing as well as the ground.water flowing through it. This insulator also maintains the permafrost level at a constant point through the summer. Because it has not frozen during the winter the ground water continues to percolate through the ground until it e- ventually seeps to the surface because of some obstruction to its flow. When this happens, as described earlier, the water freezes almost immediately upon contaCt with the air starting an icing. 15 The robl p em of icings and methods of possible control will b 0 . e further discussed later in this paper 16 PERKAFROST AND RELATED ENGINEERING PROBLEMS Background and.Hi§tory This phenomena known as permafrost has caused the United States Government untold headaches in the past five to six yearsin its military program for Alaska. Although permafrost has exist- ed under the ground in Alaska and Canada for hundreds even thousands of years, it was not until this last world war that the U.S. had any real contactwith it. The war brought to light the importance of the territory as a vital defense bulwark. As such, it had to be equipped with military camps and air fields. Then, even before these were considered, the problem of trans- porting men and equipment to Alaska without the use of ships, caused the decision for the construction of the Alaskan Highway to come about. It was all very easy to talk of such things and legislate money for the carrying out of such proposals, but to . make them fact was an entirely different story. When the Army and the Public Roads Administration went into this construct: ion program, they ran headlong into the permafrost problem and at the end of the war were still stimied for a totally accept- able cure for the situation. The end of the war brought about. no end to the fight either. It is still a vital problem today. Opportunities for colonization to increase and.untapped mineral . resources are two verygood arguments Why this freak of nature must in some way be conquered or dealt with to the extent that man can go ahead with construction of buildings without any special consideration for soil reactions. 17 The problems and headaches this country has been experienc- ing may come as a new and strange story to the reader, but records show that the Russians have been battling permafrost for some twenty years. Ever since they began development of Siberia in the middle twenties, soviet engineers have watch- ed their buildings fail miserably under the actions of perma- frost. The resulting use of more rigd designs and stronger materials only saw the failures become more and more expensive as the cost of the materials and designs rose. The fight goes on, however, with strict regulations as to who may try to out- wit the tricky earth actions. Since 1938 in Russia no one may erect a building within the permafrost region without making a study of conditions in the area and obtaining permission of the proper authorities. Because of the fact that the experience of the Russians is much more extensive than that of ours here on this continent, mahy of the facts that follow concerning the construction of buildings, runways, roads, water supply, and other projects were contributed by Russian engineers and scientists. D With Per fr First of all in dealing with permafrost there are two courses of action that can be taken. First is called the "Passive Method". An example of this is a road built over undisturbed frozen ground with the insulating cover of moss or peat over the active layer left intact. While it remains in an undis- turbed state the permafrost will have the stability of bedrock. 1O As assurance of preserving the frozen state of the_permafrost, for example with the construction of a building, additional insulation might be added. The other course is called the "active method". This method entailsactively fighting the permafrost. The active layer is removed and replaced with more acceptable soil or the same can be done to the permafrost. If neither isremoved, designs are used that will withstand the actions of both the active layer and the permafrost. Building anstrugtign First consideration is whether the passive or the active method is to be used. From previous statements in this paper, we know that the stability of a building depends on: 1. Texture and structure of the ground. 2. Temperature of the ground and air. 3. Hydrology of the ground. In cmsidering whether the passive method or active method should be used, take for example a building to be built on bedrock. In this case the active method would not be used because it would most likely expose the bedrock to thawing temperatures which would melt any frozen water in the, rock as ice veins and leave crack for percolating to enter. With 19 the use of the passive method in this case, the frozen con;- dition of the bedrock is preserved with the use of additional insulation besides natural ground covering. The consideration of the possibility of swelling of the ground is very important in the design of a foundation. Three of the factors to be considered are: l. Adfreezing strength of the foundation to the ground. 2. The depth of the foundation. 3. The weight of the structure. The use of these three factors is of the utmost importance, because it has been found that heaving of the. foundation _ occurs when the adfreezing strength between the frozen layer and the foundation. exceeds the weight of the structure plus the force of the friction between the foundation and the permafrost. N.A. Tsytovich and M.I. Sumgin, two noted Russian. permafrost investigators, consider from experience, that foundations that consist of footings, pillars, or pilings' are the most suitable for building construction whether the active or pass- ive method is to be used. It has been. found that continuous, foundations (slab type) cannot withstand the tensional‘ stress as well as those named above. The continuous foundation is also undesirable because of the large contact surface with the ground and a high heat conductivity coefficient both of of which result in disturbances to the thermal regime of the ground beneath it. The two investigators found that with an experimental house: 1. Houses with continuous foundation‘s do affect 2. 3. the thermal regime of the gound under it. . That there is. a noticeable sag in the perma- frost table under the south-facing wall, as compared with a! rise under the north-facing wall. This is definitely on of the causes. of damage to, a structure because it obviously results in differential settling. _ . With the passing of time there is a general over, all lowering of the permafrost table . which would eventually mean that the found- ation would rest entirely on. ground that composes the active layer and offers no support. Some of the damage due to differential thawing of the ground due to solar radiation can be minimized if the long demension of the structure were placed in a north-south direction. One of the preventive measures taken to prevent the lowering of thenpermafrost table below the footings of the foundation is illustrated in Fig. F (Bykov and Kapterev). A trench is left excavated down to the permafrost table after the foot- ings and columns have been securely placed in the permafrost. 21 °°a on .\ Z PER/M ems-é ////;737= ’/ //////////% ////// HEWNG o: sconce-nous FIG-,F' This trench is filled with non-swelling fill (dry gravel). A.means of drainage is provided as well as an insulating cover of some kind to prevent the actions of frost and thawing from disturbing the foundation. The water-proof cover prevents the entering of surface water Whose presence wouldtaid the action of frost. When the ground beneath a structure is composed of clayey or silty material, it is al- most impossible to eliminate entirely the destructive effect of frost swelling. Drainage of such ground will eliminate a great amount of the moisture present, but that which is left in the ground will be enough to cause swelling of the ground under the action of drastic frost during the winter months. If these conditions are prevelant,the advisable course_is to replace this undesirable ground with non-swelling material such as clean gravel or coarse sand. The ideal type of foundation is the type that eliminates the permafrost. Fig. G (Tsytovich and Sumgin) shows this type. The ground is excavated down below the permafrost table and a fill of sand is placed in the excavated area. Around this excavation is placed an impervious wall to prevent the infil- tration of ground water from the active layer. This wall con- sists of two inch boards with four inches to a foot of clay on the outside to increase its imperviousness. The boards should extend into the permafrostat least three feet. An- other purpose of the wall is to prevent silting of the gravel and.the sand.by the ground surrounding the excavated pit. Silting of the gravel and sand plus the existence of ground 22 . 0 I I I II I I IIIIIII IIII” - III In... IIHIIIHIIIIIII I I I I OI II I II II IIII III I I I I I II C I I I I I I II’ I II I III I II I I I ~ I I I I I I I l I I II I f I: I ' I II I . I U . I IIqIIII-I.‘ I . ' . . . .. . . .. : .;.....‘m0.a)_mm0..:-..... I.- n I I .... I I I III\ I I III I III-I I I I II I II I Il.‘ II I n. «- ... o I II I I I I II I III " l I l I I 0.. 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I--‘IIII “I” I I‘ III I I I I‘I I -.I II .I II‘II I-I III‘I II II.I=W=mjzgs E3Efl«:hn%=mzu1 g \\ FHUhMB CIDLLfifizcxr Tszfihpea: ://’$hsauszss _ \ §?%fifl* Gr . . O I , v e a ,I ' ua' . .I\‘ .' . . " '_'. a". ' n‘ U: '. ;-’ I (.oz-‘w... ’ "'u .‘I “ .-I . " "‘ '.I ..‘.-“ I a . u .--_.I_: ‘-\'a'. . 33"." 'vo". 0- .nl'..'\ o'\-::.c I..."".' . H ""“.-l:’. 1“. 2-3; 3'3“ I ‘- .- \ 1‘7. 9.”ng .‘o . t ' " ‘.0."'.’o 5" ’3' 'I’u'r" J\ k ‘0 . I . . I '. i;-.;-;--2,-;-.A.,-'.;.J "kW-“17.1.13 ."u“.y I'V..' ._"~I‘_... '.' '. ---".'¢._"J - - " ‘II-I‘ .‘IS I} O. .‘ v .' ." ...“ I - u " '- . - - . . . .0 .. '1‘ , ' ' Q I. '."."". '.:-~ 7:- 1- -"- ‘ ‘ ."."\'. l"-"f.". .. ".-.".I".. serve only to move the tar paper up th pile on the lubricant. The lubricant reduces the frictional hold of the frozen layer on the pile to the barest minimum. The tar paper should be secured to the pile with the aid of a strong cord of some sort. Nailing of the paper will mean ripping the first time frost heave takes place. Setting of a bench mark in the permafrost region requires much the same procedure that is followed when setting an ord- inary piling. In the case of the iron pipe used for 'the bench mark, the depth of setting in the permafrost is equal to three times the thickness of the active layer. This means that the total length in the ground is four times the thickness of the active layer. Ice is introduced into the bottom, perfor- ated section of the pipe to speed the adfreezing of the perma- frost to the pipe. In the top section that will be in active layer before it is removed, a fill of non-swelling material such as sand is placed. As for the efficiency of the method of placing muffs or collars around foundations and pilesihas been found to be effective for one year and rarely for two years. The technique is not sufficiently perfected to insure permanent safety against frost heaving of foundations. For some reason the muffs of collars seem to work smoothly during the first year after installation, but after that they seem to edfreeze to the foundation or pile. 25 Qonclugions 5211 Prevention 9f Frost Heaying 9f Foundetiong 1.. TR) prevent or minimize the freezing of the active layer to the foundation. As described earlier this usually means the installation of muffs or collars around the piles or foundation. 2. To remove the causes of swelling by draining the ground or replacing it with non-swelling ground. :3. To cover the surface of the foundation with substance that will prevent or greatly minimize adfreezing. One experiment that is in process is that one that calls for the use of parafin to reduce the cdhesion between the frozen ground of the active layer and the pillar. 4. To anchor or add weight to a foundation to counteract the heaving force of frost. ._ The only method of anchoring that has brought any king of satisfactory result is that which sees the foundation placed within the permafrost for anchoring. 26 Bgad,an§truction When a road is being planned in the permafrost region,the choice of route cannot follow the usual pattern of selection. The most important factors to be considered are: 1. Location of the roadway with reference to the slopes of the relief. 2. The angle of the slopes. 3. The thermal and.hydreulic regimes of the slopes. 4. Nature of the ground. An example of some of the conditions that might be encountered during road construction in the permafrost region is shown in Fig. K. The top illustration shows the condition of the area before construction is started. In this case the surface of the ground consists of swampy material with a great amount of ' water percolation through the active layer. The flow is accentu- ated by the slope of the ground to the left. The second ill- ustration shows the constructed fill. In accordance with the 'usual behavior of permafrost, after the fill has been built, the permafrost table rises within the fill as shown. It rises,- in most cases, above the level of the surface of the active_ layer. This will result in the condition of ponding of water on the up-hill side of the slope from the fill. The bulging of the permafrost table presents an impervious barrier for ground water on the up-hill side of the fill. As a result, the water 27 I/L/////// WDED WFTT'ETZ. acme / I... “I ~ ['71, // 1/ / , ”lull “I v / / /7 / /'l/ '/ / lgquW/Z/ // /// (New Roan-ICU OF" PF? ‘TDBLE Pm F=1L—L.. Is Butt!" DZQIUHGE III"' PEZMr-ao/ M l , , / {\ H’////////// 7777777777777 F"\G-. ‘< is forced to the surface and ponding results. On the down-hill side of the fill, the swampy area becomes drained eliminating the insulating effect of the water which results in the perma- frost table being lowered when the active layer thaws cauSing the permafrost to thaw. This produces an unstable condition under the fill on the down-hill side which may result in slumping of the fill. On the other hand, on the upghill side of the fill ponded water causes a sage in the permafrost table directly under it. The water will move along the fill seeking ‘ someplace Where it might breach this barrier the fill presents. This condition is favorable for slumping and damage to the fill. The frequent use of culverts will somewhat remedy the situation. The last illustration Shows one method used to pre- ‘vent some of the undesirable conditions that exist in the second illustration. Here berms of materials that are poor conductors of heat have constructed on the up-hill and down- liill sides of the fill. The berms, as shown, with their in- sulating effect cause the permafrost table to rise beneath them Which means that the fill will be resting on as solid a / foundation as can be found, permafrost. A drainage ditch is constructed up-hill from the up-hill berm to conduct away to culverts or any other similar type of cross drainage structure such surface and ground water that may appear from up the slope. The way that these same berms preserve the frozen condition of the ground.beneath a fill is shown in Fig. L (Bykov and 28 s i \sssssssssss fie \ \/\\\SS\\\\\\\\\\\\\\\\\\\ww\\\\ E INum. / Jan \ E 9.0.3. “0 NM: .m1.r__..E3 JJE Dan”. .u 2.2% Q1380 Zuuflflu "I... .92.; s a fiss\\\\\\\\\\s\\\\\s “U. now/.380 N\\\\\\\\\\\N\\\\\\REE\\\\\\CE?QNQQEESQ r ZNMQ / JJE \ E / Oflgfi =16. \— Kapterev). The top illustration Shows the presence of the berms When the climatic conditions are such that there exists a frozen active layer with ground ice present. With the com- ing of a thaw, the berms react in the manner shown in the lower illustration. The ground ice melts and the active layer thaws both to the right and left of the extent of the berms. The insulating effect of the berms preserves the thermal regime of the ground under them which allows the active layer and ground ice to remain in a frozen condition providing a firm foundation for the fill. WW Formation of icings in the area of road fills is probably the most persistent problem that has tobe fought where roads are built at the bottom of a slope or a valley with fairly steep sides. Fig. M illustrates first of all how an icing is form- ed with the road fill located at the bottom of a slope. The ground water percolates down the slope beneath the frost line and above the permafrost through the unfrozen portion of the active layer. When the water reaches the road fill, however, it finds its path blocked by the rise the permafrost table within the fill. This rise shuts off the water bearing layer and the water is forced to flow upward where it seeps to the surface forming icing "A" in the illustration. This condition can continue to the point where the icing forms to the extent that it will cover the road. One solution to this problem is also shown in Fig. M. It is the use of the Frost Belt Method or "induced icing method " which allows an icing condition to form some distance up the slope from the road fill. In this method, above, the road fill on the slope a trench is dug 5 to 6 feet wide down to the perma- frost table. The trench is filled with clay or with water saturated silty. or clayey ground, and is welltamped down. Down into the trench is then Idrivenha row of planks side by side to form a variation of sheet piling. Then both sides of the planks are covered with fill. This fill will cause the permafrost table to rise within theground and trench and 30 /// an. / \ . w .1 V .3 ... E..¢U7=U_ _ . .. U . , Gammmd m9 JJfiu 0G8 H»\V\ ‘ x \x ing/.... a. ground beneath it to seal off the path of the“ percolating . . ground water. If a trench is dug behind the planks and fill, this will further aid the efficiency of the trench, planks, and fill. The trench will expose the ground to deeper freez- ing. If this freezing is deep enough itlwill extend to the permafrost table and also seal the path of the percolation. of the ground water. With its course of travel through the ground out off the ground water is forced to the surface to form icing "B" where it can do no damage. It has been. found that this method is the most satisfactory of all those tried. 3]. BEQE QQNfiTREETION Little success has been awarded the efforts to find a metho of placing pilings for the support of bridges over streams and rivers in the far north. Almost every bridge site presents a problem which is peculiar only to that site alone. The thermal effect of the water has a way of causing a de- pressiOn in the permafrost table directly below the stream or river. This is one factor that must be taken into serious con: sideration when the necessary depth of pilings is being figured.. Deep rivers or streams have been found to be the safest water- ways to try to bridge. Whereas shallow streams, in most cases, freeze clear to the stream bed which inevitably leads to the formation of an icing upstream which can become large enougl to destroy the bridge, deep rivers and streams almost never have a totally constricted water channel due to freezing. Men in the field say the whenever possible the use of a sus- pension bridge should be employed. 32 CW If the reader merely recalls some of the varying soil condi- tions in northern areas discussed earlier in this paper, he will realize what a task it met be to find an area large enougi for a landing field with acceptable soil conditions. One use of the passive method of constructicm covered the un- distrubed surface of the ground with a layer of material of low heat conductivity such as pumice, slag, porous lava rock, air entrained cement, etc. and then surfaced with cement. New methods being experimented with will be discussed later in this paper in the section dealing with the tests that are in progress in Alaska. 33 WNW B WE The following facts are for the most part suggestions made by the U.S.S.R. Academy of Science Committee on Frozen Ground 'headed by M. I. Sumgin. These suggestions stem from the re- sults of experiments and experience with permafrost and.repres sent the methods now being used by the Russians. The following complete permafrost survey can, in some cases, require a year to complete. If, for some reason, an emergency arises which would demand all possible short-cuts, extreme caution Should be taken. Important factors might be overlook- ed which could mean failure of the proposed project. W The survey of the permafrost problem.for any project can be listed as six related elements: 1. Topography 2. Earth Materials 3. Hydrology 4. Climate 5. Botany'(ecology) 6. Laboratory tests and experiments 1. Topography Topography is very important because the actions of permafrost will differ, for instance, when it is located.on a mountain side from when it is located an adjacent floodplain. Floodplains with general 34 2. characteristics of impeded drainage are'm'ore likely to be underlain by silty- gound and to contain 1°91 lenses and wedges. However, in a well drained basin, gravelly ground is of more common occurrence. A geologist well founded in geomorphology, _ the study of land forms, should. be assigned the ,job of in- terpreting topography. Earth Materials _ . This is one phase of the work where the geologist nust ask the aid of a soils engineer. Their job is to study those materials such as soil, unconsolidat-_ - . ed clay, silt, sand, and gravel which are the materials affected by frost action. They will include the. study of the composition, thickness and structure of the seasonally and permanently frozen ground as well as the distribution of each type of soil that makes up.those two types of fi'ozen ground. The soil engineer will perform the following tests on soil samples: grain analysis of the sample, moisture content, specific gravity, liquid limit, plastic limit, plasticity index, consolidation test, shrinkage test, natural density, California bearing ratio, plate bearing test, compaction test, etc. The results of the findings of the geologist and . soils engineer Should for final analysis be compiled 35 SCHLE I"- 30¢M'r. g \ 0W m s ZHETRS 390 THICKNESS os- * "’ ‘ m3? mu: Lax/E2 . ‘- mum: ' ‘ ‘ Lew news , 4 'LHRCH , 3L SHRUB . ‘ \ ICING' ' . MOSS-I 3‘ H p \. (Um y) B‘ECH ‘ ' BWHHP ‘ Moss nousz GWEN” [E i .L ‘ PEZMHFZOST 8(31-0-4 mar: as. k] 3. and graphically presented on a "permafrost map" simi- lar to the one in Fig. N (Yanovsky). This map shows the existence of two terraces. _The;;- lower appears to be very unfavorable.- As shown there is a large icing at the foot of the slope frcm the upper terrace as wellas numerous ice mounds 907’??? ing the lower terrace. The lower terrace is cover- ed with vegetationtwhich would indicate that the. ground cf the active layer is o‘ver‘saturate'd with ; moisture. On the other hand, the vegetation of'the upper terrace indicates that it is well drained. After these conclusions was made, they were sub- stantiated by the employment of test pits in the ~ . field by Yanovsky, a Russian permafrost investigator, from whose works this map is obtained. Hydr°1°w .. _ . -s . . It is of the utmost importance that this investiga- tion be put in the hands of‘a hydrologist who can handle the surface water problem. Working with the geologist, the hydrologistwill study the character and thickness of the_active.t layer, the constancy of this thicknessover an area, moisture content and.permeability of'the ground, H thickness of the permafrost, depth of the permafrost table, profile of the permafrost table, etc. 86 4. 5. Climate All available climatological date should be gather- ed from local meteorological and weather stations. In addition to this data, observations should be made to obtain : a. b. Botany Temperature of the ground. (Daily record- ings of temperatures‘at various depths below the surface several times a day and in varied landscape surroundings.) Amount of solar radiation. - A This amount is obtained with the use. of _ . sensitive instruments such as- heliographse ' This subject also covers the effect of solar radiation on heat absorbing surfaces (run- ways, pavements, , etc.) which enters into. the computation .of the thermal regimen of the ground underneath or immediately ad- a‘acen'e- _ ._ Gaging of. streams and other periodic ob“, servations‘ on rivers, lakes, springs, thick- ness of. ice,duration of ice, freeze up, break-up, etc . Geologist or soils engineer, preferably abotanist- ecologist should note the commonest plants, their associations and distribution. This information 37 6. should be correlated with the permafrost condition of the terrain as revealed by the soil profiles in test borings. Laboratory tests and experiments A field laboratory should be established. on the site of the project so that undisturbed soil samples will undergo the least possible change in condition while in transit from the site to the labcratory. All soil tests should be run in the field so that the results will be available immediately to allow field investigation of the project to continue without de- lay. ‘Ihe data of the geologist, soils engineer, hydrologist, and meteorologist are puttogether and processed: After the data has been coordinated by a physicist-5 ‘ engineer, it is turned over to the civil engineer who uses this data to design the projected structure. 2W For any engineering project. in the permafrost region shall consist of the following three stages: 1. Reconnaissance Sirvey 2. Preliminary, Survey 3. Final Survey Reconnaissance Sirvey — A reconnaissance survey consists of” - examining the terrain from the air and of selecting of several tenative sites. It should be started in the spring before the break-up of the ice in rivers, before the melting of the ice . and icings, and while the frost mounds are still at their max- imum. With other conditions being equal, preference is given to construction sites which are: 1. Flat and dry. 2. Not subject to floods.t 3. Free of gound water seepage which freezes in the winter. 4. Free of swamps, frost mounds, and cave-in I lakes. . . _ __ 5. Entirely free of, or with only a thin layer of moss. ‘ 6. Distant from mountain slopes. Areas at base of slopes are more likely to have ground water seepage, ground ice, and subject to intensive frost heaving. 39 7. Distant from canyons and gullies. Preliminary Survey - This survey is carried out to select— the most satisfactory of the severalWhich were tentatively chosen during the reconnaissance survey. This survey should- ‘be carried.out during the spring, summer, and early fall and should aim to obtain the following information: 1. Topographic map (contour interval not more . than five feet) of the siteand vicinity to obtain some idea of the drainage. 2. Location on this map of proposed water mains and sewage pipes, with profiles along these lines._ _ _ .A . 3. Distribution of vegetation in vicinity of site. 4. Character of the ground profile orcross section along several directions across the site. This is done with the aid of . soil borings. . 5. Conditions in permafrost areas that insure stability of buildings: a. A considerable thickness of permafrost, not less than 75 feet. V b. Permafrost free of moisture or permae frost with moisture (ice) content not exceeding saturation. c. Homogeneous and evenly-thawing active 40 layer where this layer does not ex- ceed 5 or 10 feet. d. An active layer that does not swell (sand or coarse aggregate containing. less than 8% of fines - grains smaller Final Survey - This survey should begin after the completion of the preliminary studies and should be carried out in the fall and through the winter. Under favorable conditions this investigation may be completed by August or September of the following year. 1. It is desirable that the person Who is to be in charge of the completed project or who is concerned with the design of the project, and who is, therefore, well informed on the function and behavior of the structure, should participate and cooperate in this final invest- igation . 2.This survey is made to supplement the inform- ation obtained in the previous surveys so as to furniSh all the necessary data for planning and computation of specifications of the pro- jected structure. Therefore, the following in- formation is called for: a. More detailed topographic map of a more restricted area - the actual 41 C. d. 0Q site - with the contour interval about two (2) feet. More detailed information on the - ground water regime._An additional number of soil borings might be necessary to obtain this inform- ation. These borings should be made at the time of the maximum seasonal thaw. Moisture content of the active layer and of the upper part of the permafrost. Some of this _ information is necessary for the computing of the adfreezing strength of the ground, and var- ious other types of behavior caused by the presence of moisture in the soil. . . _, More detailed record of the ther- mal regime of the ground. More accurate date on the perma- frost table. _ Detailed analysis of the nature and amount of Swelling of the\ active layer. _ Laboratory tests of physical properties of soils. 42 3. In October, after all these observations have been completed, the building site is stripped of vegetation and sod, and is appropriately graded. During the win- ter the snow should be kept off the sur- face and.in August or September of the following year all observations on the depthof the permafrost table should be repeated with observations made also as to the temperature regime of the ground. The Observed.change in the level of the permafrost table should be accurately recorded. It is of the utmost importance that the fact that the period required to complete the necessary surveys may in most cases require a year or more. Any Shortening of the regular length of time with the useof Short-cuts might result in leaving out of consideration factors that are critical to a partic- ular problem with the possibility of subsequent partial or complete failure of the project. 43 .. .T-III chill. ‘ .431! [If Ital-Ii . THE PRESENT AND FUTURE PERMAFROST PROGRAM 1 HE ALASKA STORY The Alaska Story is the story repeated several times earlier in.this paper. That is the first half of the story. "That half contains all the failures that resulted.in attempted construction in Alaska during the last five to six years. Because of these failures, the second half of the story was evolved - The.Alaskan Permafrost Program. This program was initiated by the Chiefof Engineers_and assigned to the St. Paul District, Corps of Engineers in January l945. The program.is still under way under the direction and supervision of Colonel walter K. Wilson, Jr.,-District Engineer, and Will, most likely continue for several years. It was the generosity of Mr. Henry J. Manger of that office that allowed the facts concerning the present program in.Alaska to appear in this paper. The purpose of the program is primarily for the purpose of developing design criteria and.construction methods for air- field pavements, structures and utilities located in arctic and subarctic regions. Objectives of various phases of the program include: 1. The determination of the performance of existing airfield installations on permafrost. 2. The observation and.correlation of the relationship 44 between climatic conditions and soil conditions throughout Alaska. 3. The determination of the thermal properties of typical soils from Alaska. ' 4. Study of heat transfer in granular media and the development of formulas fbr the depth and.rateof thaw under runways, roads and.huildings. 5. Review of available literature on the subject of permafrost. . 6. Development of a method of identifying permafrost areas and soil types from terrain characteristics shown in aerial photographs. ‘ 7. Study of the feasibility of using geophysical methods for the location of permafrost with respect to depth and extent. Field, laboratory, and office studies are being made to attain the above objectives. ‘The field force in Alaska consists of a survey crew, drill crew, soils technicians, and temperature observors. Laboratory work is being done on thermal properties of soils and insulating materials by the University of Minnesota and.otherpretation of aerial photographs by Purdue University. Studies are being'made in the St. Paul District office to corre- late the data and information collected, make theoretical analyses, and prepare reports. Carrying out of objectives - One of the first projects in the ‘program was the investigation of existingrairfield installations. 45 in.Alaska. Because of the fact that most of the fields were shut down and personnel removed with the coming of'VJ Day, the investigation was limited to the airfield at Northway, Alaska. This investigation is still underway at Northway.i At this airfield, core borings were made through the frozen - soil to depths of 30 to 50 feet. The borings were logged and samples recovered were tested for physical characteristics. The borings were made along the runway and in and nearthe buildings, and.mercury thermometers or thermocouples were installed in them at various depths below the surface for the purpose of observing the Change in temperature over a long period of time. Ground water wells were also established throughout the area and.vertical observation points install- ed on the runways andstructures. By means of periodic ob-: servations on these installations, it is possible to observe movements of the permafrost table, fluctuations in the ground water level, and.vertical movements of the runway pavements and structures. These observations have been made for about two years and indicate that the permafrost table under the runway has reached equilibrium at aboutten feet below the surface as compared with three and one-half feet under the‘ 11ndisturbed ground nearby. They also indicate that heat is still being transferred downward.under the hanger, causing a _ progressive recession of the permafrost table. The permafrost table under the hanger at Northway,_Which was built in 1943, , is now about 24 feet below the floor level. Vertical observa- tions on the hanger floor and abutments show a maximum settle- 46 ment at one elevation of approximately one foot. In addition to the investigationof existing airfields, it was considered advisable to study other types of construction to observe the rate of flow of heat through various types of materials and its effect on permafrost. ‘To accomplish this, a research area was set up near Fairbanks, Alaska on fines grained soil Where the permafrost_table is from_3 to 4 feet. below the surface. This research area is divided into three sub-areas: Area One - This area is being used principally teo. determine the effect of climatic factors, such as air temper- atures, solar radiation, wind velocity, humidity, cloudiness, and precipitation. One portion is left in its natural state; the next has bad.bru3h and trees stripped to a dePth.°f12.g inches.‘ In each of these sections are installed temperature xneasuring instruments, verticalmevement observation points,, and ground water wells. The remainder of Area One isdesign- ed.for solar radiation observations. Three concrete slabs,uw 30 feet by 30 feet, all six inches thick, will be placed, with one painted White, one black, and the third.left in natural- concrete. Automatic temperature recording apparatus will be installed to determine the effect of color on the heat trans- fer into the ground. . Area Two 3 This area is composed of twentygsix-run- way sections, each 5O feet by 50 feet, with a temperature well in the center of each section. The depth of the base 47 course varies from two to twelve feet and the surfacesare- concrete, asphalt, and gravel. Insulating material-has been included under the base course in several of the sections. Insulation material used was spruce boughs, moss, Portland. Cement Foamglass, Zonolite Concrete, and Cellular Concrete. The insulation material is placed in the base course in a ., layer two feet below the surface of the runway. The bearing strength of the insulation does not lend itself to direct loading. Cellular concrete is a product which is made in a;. special mixer, using a foam compound, which causes air bubbles to form.in the concrete making it lighter and adding to it§if insulation value. Zonolite and Portland.Cement Foamglass are commercial insulators used in standard.building constructien. The natural surface was stripped to a depth of_one_foet:for 23 of the sections, and the base course for the remaining‘. three sections was placed on natural ground. It is expected that, from a careful study of the transfer of heat through each runway section, a guide for the design of_a stable run- way at minimum cost can be very easily developed. f Area Three - This area is devoted to twotypesipf: experiments. iThe first consists of eight buildings, 16 feet by 16 feet, and is a study of different types of_foundations‘: under'heat“ed‘buildings.l Buildings are heated toga temperature of 60 degrees F. and several temperature wells have been ins stalled under each buildingui Under five of the buildings,the base course is gravel ranging from two to six feet. One 48 building is placed on mud sills directlyon the natural ground, and the other two on posts extending twoand one-half feet‘. above the natural ground, to allow for free air circulation.' In another section of Area Three, pilings have been placed in the ground with the penetration into the permafrost varying from zero to three times the thickness of the active layer. This test is to determine the effect of adfreezing to the piling and.the depth at Which the piling must be placed to prevent being dislodged.by the force of frost action in the active layer. 'Tests todetermine the thermal conductivity and specific heat properties of certain soils, rock types, and insulations at various densities, moisture contents, and temperatures, are 'being made by the Engineering Experiment Station of thetUnd- versity of Minnesota under a contract with the Government. As the various reports on tests and observations from the University of Minnesota field sources in Alaska, library,- and theoretical studies are collected, it is planned to corref late the data, evaluated.the results, and produce, if possible, guides for the design and construction of airfields in perma- frost areas. The Government has a contract with Purdue University to deter? mine the feasibility of using air photos in identifying perma- frost areas on the ground. By a study of air photos,_corre- lated with extensive field trips in the same areas, it has been possible, from existing air photos of surface details such 49 as drainage, topography, types of vegetation, and tree growth, to select areas Where construction can be successfully carried out, as well as those areas which Should be avoided at all ~ cost. This program is being continued again during the summer_ of 1948, and, if it continues to be successful, may eventually repay the entire expense of the whole permafrost program. It has been found that the air photo method can eliminate long and extensive ground explorations by selecting the most suit- able site in a large area and that ground explorations can confirm the detailed location. As air photos are studied, one elementconsists of identify- ing the type of vegetation and inferring the permafrost, condition from the knowledge of those trees and shrubs that generally are in frozen ground or thawed ground. Wherethe vegetation is well established, it plays an important part in establiShing the degree of permafrost or depth to permafrost. Another element is land forms. The most direct information that comes with the identification of_a land form such as a terrace, a recent alluvium, a dune, an esker, or a moraine is the texture and uniformity of the soil. 50 CONCLUSIONS Mr. Henry J. Manger, Chief of the Permafrost Division in the St. Paul Office of the District Engineer, has drawn several conclusions as to how to deal with permafrost based on results thus far obtained in the Alaska investigation. The fact that there is no other more authoritative source for comment than Mr. manger, his opinions will form the concluding statements. of this paper. In a report presented at one of the quarterly‘: meetings of the American Society of'Civil Engineers, mr. Manger said, "It will require several years of observations in.Various locations and under a variety of conditions to determine thermal characteristics of permafrost areas and to develop design cri- teria and construction methods as a guide to construction engi- neers. Although definite conclusions cannot be made at this time, there are certain trends Which engineers would do well to consider in new construction in permafrost regions. 1. Site selection is very important and.whenever possible, structures should be located on areas of coarse- “ grained.materials where the lowering of the permafrost table will not cause settlement of the structures. 2. In areas where there is danger of settlement by lowering of the permafrost table, an air space should be pro-i vided.under heated buildings to prevent heat transfer into the ground. 3. In the construction of roads and runways, all 51 fine-grained material in the subgrade subject to frost action should be removed at least through the frost zone and be re- placed by coarse-grained.materials. 4. Where pilings are used under structures, the pilings Should be placed at least twice the depth of the frost zone into permafrost to prevent uplift by frost action in the active layers. 5. Where there is danger of icing over runways or . roads, consideration should be given to causing induced ieings some distance from.the structure to prevent icing over the structure. . _ . . _‘ 6. By thorough knowledge of the soil characteristics and the extent of permafrost, it is possible through proper: construction methods to avoid settlement or ultimate failure to structures". 52 GLOSSARY These are definitions of terms used in this paper that may be new to the reader. Active Layer - Layer of ground above the permafrost which thaws in the summer and freezes in the winter. Also referred to as ”seasonally frozen ground". Active Method (of construction) - method in which permafrost is dealt with by changing its natural frozen state before construction. Adfreezing - The process by which two objects adhere to one another owing to the bindfing action of ice as result of freezing of water. Adfreezing Strength - Resistance to the force that is required to pull apart two objects which adhere to one another as a result of freezing of water. Berm - A bench or horizontal ledge used for the_preservation of the thermal condition of the ground under it. Frost-Belt , A ditch that causes an early and.rapid freezing of surfaced ground water forming an obstruction to percolating shallow ground—water. Frost-Blister - A mound or an upwarp of superficial ground caused.chiefly by the hydrostatic pressure of ground water. 58 Frost Heaving - An upward force usually noted by a more or less marked upwarp due to the swelling of frozen ground. Frost Mound - A seasonal upwarp of land surface caused by the combined action of (1) expansion due to freezing of water, (2) hydrostatic pressure of ground water, and (3) force of crystallization of ice. Icing - A mass of surface ice formed during the winter by successive freezing of sheets of water that may seep from the ground, a frozen river, or from a spring. Layered Permafrost - Ground consisting of permanently frozen layers alternating with unfrozen layers. Passive Method (of construction) - Method which does not disturb or change the thermal condition of the ground. Percolation — Is a type of flow of water in interconnected openings of saturated granular material under hydraulic gradient. Permafrost Table - A more or less irregular surface which represents the upper limit of permafrost. Seepage - The percolation of water through the surface of the earth or through the walls of large Openings in it. Slud - Ground that behaves as a more or less viscous fluid. It may occur as‘a layer or lens beneath thesurface and may at times be under considerable hydrostatic 54 pressure. It is "Solifluctional Ground" but it is not restricted to the soil material and its movement is not limited to gravitational flow. Solifluctional - The process of denuding an area which consists of the slow gravitational flowing of masses of surface materials saturated with water. Swelling Of Ground - Increase in volume of surface deposits due to frost action. 55 ,r.._l.H3...l. r: BIBLIOGRAPHY Article Author - Publication "Permafrost - Menace of the North" Science Digest August 1947 "Permafrost Is Sure A Devil" W. Davies & W. Peake Nation's Business Nov. 1947 "Test Study of Foundations and Their Design for Permafrost Conditions" Engineering News September 1947. "Studies to Determine Proper Construction Procedure in Permafrost Areas" Civil Engineering July 1947 "Alaskan Permafrost Investigations" HJJ. Manger Civil Engineering August 1947 "Research on Permafrost Foundations" R.M. Hardy Roads and Bridges September 1946 ”Frozen Assets" A. Lane & H. Nichols Christian Science Monitor May 1948 "Pesky Permafrost" Time Magazine November 4, 1946 "Civil Engineering in Frozen Soil-USSR" A. Dementiev & V. Tumel Canadian Geograph. Journal January 3, 1946 "Russia's Frozen Expanses Have Lessons For Us" U.S. Science Magazine July 18, 1942 "Permafrost Problems" L.A. Palmer Civil Eng. Corps Bul. No. 17 April 1948 56 Article Author - Publication "Ice Formation on the Alaskan Highway" W. Eager & W. Pryor Public Roads January 1945 "Some Problems of Road Construction and Maintenance in Alaska" Stephen Taber Public Roads July 1943 "Essentials of Foundation Design in Permafrost" J.D. Lewin Public Works February 1948 "Dams in Permafrost" J.D. Lewin Pub 1ic Works May 1948 "Permafrost" Federal Sci. Progress May 1947 "Permafrost or Permanently Frozen Ground and Related Engineering Problems" S.W. Muller Pub. 1947 All persons mentioned in this paper in connection with the illustrations used originated in the publication by S.W. Muller mentioned above. 57 VII: "V”. ' .-.‘.f.-v.'.' r W'"'. 'v‘ 0- “at" . .... 4'- , —»«.— v £9 3% Feb ‘8 ‘55 ‘ Mr 7.1-3 58 I 1'" ...—n+-vl-"" ' .- A-F . 5b a U iv ~.- A man-12 4va 3: ‘~ r, n the, JM?) 1953”“??? J ". _ A“ Roy 2'4 68-6. ' 2 «:‘m'wrrw '1' 3 129 I ‘ ‘ 1 1 ‘ 303