TESTING OF HIGH WATER CONTENT COHESIVE SOILS USING THIN-WALLED TEST CELLS by Henry Francis Schultz United States Naval Postgraduate School THESIS Tf STING SOILS OF HIGH WATER CONTENT COHESIVE USING THIN-WALLED TEST CELLS by Henry Francis Schultz Th ssis Advisor: R. J. Sm ith March 1971 App/ioueci (Jo/l public nzlzcAz; dUtnlbuJxon ujiiunltzd. T Testing of High Water Content Cohesive Soils Using Thin-Walled Test Cells by Henry Francis Schultz Lieutenant, United States Navy B.S., United States Naval Academy, 1964 Submitted in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE IN OCEANOGRAPHY from the NAVAL POSTGRADUATE SCHOOL March 1971 LIBRARY NAVAL POSTGRADUATE SCHOOB MONTEREY, CALIF. 93940 •'- ABSTRACT The concepts associated with the field of soils mechanics are now being applied to marine sediments. Because of the more complex nature of the mixture of fine mineral particles and sea water, some of these concepts do not always appear overly applicable. This is parti- cularly true with regard to the deep sea clays . In view of their often very high water contents, a liquid behavior might well be assumed for many marine clays. The analytical methods of fluid mechanics do not satisfactorily explain the low strengths that are found in these soils. Thin-walled test cylinders were devised to allow testing of cohesive soils at high water contents. Over 50 tests were made of a test sedi- ment, the majority above the liquid limit, to study the relationship of plasticity to water content. The results show that the gradation from liquid to plastic behavior encompasses a much wider range of water con- tents then previously considered. TABLE OF CONTENTS I. INTRODUCTION 5 A. GENERAL 5 B. FAILURE OF SOILS UNDER LOADING 7 C. SIGNIFICANCE OF COHESION 10 D. BASIC EXPERIMENTAL APPROACH 12 II. TEST EQUIPMENT 17 A. NPGS UNCONFINED COMPRESSION TESTING MACHINE 17 B. TEST CELL EQUIPMENT 17 C. AUXILIARY TEST EQUIPMENT 23 III. TEST PROCEDURE 24 IV. ANALYSIS OF DATA 31 V. RESULTS 35 VI. CONCLUSIONS 37 A. Kq-WATER CONTENT RELATIONSHIP 37 B. TEST CELL APPROACH 38 VII. RECOMMENDATIONS FOR FURTHER STUDY 40 APPENDIX A TEST DATA 41 BIBLIOGRAPHY 69 INITIAL DISTRIBUTION LIST 70 FORM DD 1473 71 LIST OF FIGURES 1. RELATIONSHIP OF PHYSICAL STATE AND WATER CONTENT 6 2. INCREMENTAL SECTION OF TEST CELL 14 3. NFGS UNCONFINED COMPRESSION TESTING MACHINE 18 4. ELECTRIC MOTOR AND MACHINE SCREW JACTUATOR 19 5 . ELECTRIC MOTOR CONTROLLER AND FORCE TRANSDUCER 19 6. TEST CELL WITH STRAIN GAGES ATTACHED 21 7. STRAIN GAGE INDICATOR 22 8. TEST CELL CROSS SECTION 26 9. TEST CELL READY FOR TESTING 27 10. FORCE VERSUS TIME OUTPUT GRAPH, MODULATED TO INDICATE INCREMENTS OF STRAIN 29 11. SAMPLE P VERSUS P GRAPH 33 12. KQ VERSUS WATER CONTENT GRAPH 34 I. INTRODUCTION A. GENERAL The requirements for accurate estimates of strength of marine sedi- ments are numerous and are increasing. The methods used to make these estimates have not always fully satisfied the requirements. Diff- erences between in-situ and predicted strength characteristics have been at least partially attributed to sample collection techniques. As a result, much effort has been devoted to both improving sampling equipment and perfecting in-situ testing methods. The former approach has had little direct result and the latter has proved costly, and at present, impractical. A third approach, that of correcting laboratory data for in-situ con- ditions, requires a good understanding of the nature of these marine clays and the basic reason for their strength characteristics. The in- situ strength of a sediment is a complex function of the physical proper- ties, both on a mass scale, and relative to each individual particle. If the particles were the same size, shape, orientation, and chemical composition, the problem would be far simpler. The marine clays, the most complex of bottom sediment types, are among the most important, in that the majority of both near-shore and ocean basin floor is composed of clays. The nature of these clays is varied, ranging from fine mineral particles of predominantly terrestrial origin, to oozes composed mainly of the remains of oceanic flora and fauna. Three similar properties exist, though, in marine clay types, which allow generalization of strength characteristics. They are all fine particles, have high water contents, and exhibit cohesive strength. The test methods most commonly utilized in dealing with these clays are those developed in terrestrial soil mechanics. The differences which exist between marine soils and terrestrial soils is a factor of their different environments, with the major difference being their higher water contents . The strength of a soil body is a property of the physical state of the soil. Soils can be considered to be in one of four states; solid, semi-solid, plastic, or liquid. The state of the body determines which theories of mechanical behavior are applicable. The physical state of a soil body is, to a large extent, a function of the water content. To determine the state, and therefore the applicable theories, the Atterburg limits are used. Figure 1 shows these limits, as delineations between the various states, and their relationship to water content and volume. v o L U M E SOLID LIQUID L L WATER CONTENT FIGURE 1. RELATIONSHIP OF PHYSICAL STATE AND WATER CONTENT The liquid limit (LL) is defined as the water content at which a soil passes from the plastic state to the liquid state. The plastic limit (PL) defines passage between semi-solid and plastic states, and the lesser used shrinkage limit (SL) marks the change from solid to semi-solid (Atterburg , 1905). The methods used to determine these limits are empirical, but usually fairly reproducible. Some question arises in these definitions with reference to marine clays as to the validity of the various regions, primarily in regard to the transition from plastic to liquid region. B. FAILURE OF SOILS UNDER LOADING The mechanism of failure of a soil column undergoing testing is ascribed to slippage along a plane, considered as the plane of failure. The resistance to slippage along this plane is termed shear strength. This resistance is caused by two separate mechanisms, internal friction, and cohesion. Internal friction is that strength given by contact of indi- vidual particles. Cohesion is a more complex quantity, and will be dis- cussed in the succeeding section. The first relationships developed to understand the meaning of shear strength were devised by Coulumb (1776), in his early studies of retaining walls. His equation states: S = C + P tan £ where S = shear strength C = cohesion, P = normal force per unit area , and fi = angle of internal friction From the above, the resistance to slippage along a plane is equal to the cohesive strength plus the component of the normal force parallel to the plane. Coulumb assumed cohesion and angle of internal friction to be constant for a given material. The studies of Terzaghi and Hvorslev (Hvorslev, 1937), however, demonstrated that these assumptions were not valid. Their work resulted in the Terzaghi-Hvorslev failure criterion: S = C + P'tan ^' where C, P' , and rf ' denote effective values of the parameters. The effective normal stress (P1) was found by Hvorslev to equal normal stress minus the pressure of the pore water: P' = P-U o where U = pore pressure. The effective values of C and $ account for variations of these parame- ters with water content, orientation, and pore pressure. Hvorslev1 s experiments on natural clays during the period 1934-1937 (Hvorslev, 1937) illustrated the applicability of these parameters. When applying the Terizaghi-Hvorslev criterion to fine grained marine sediments, the assumption is usually made that rf ' approaches zero. The reasoning for this assumption is that the increased water content tends to separate the particles so as to prevent contact or fric- tion development. The tangent of 0° = 0, and the equation simplifies to: S = C This indicates that all shear resistance in soils of high water content is attributable to cohesion. The mechanism for determining shear stress resulting from an applied normal stress is attributed to Mohr (1914). The Mohr circle is used to determine the interrelationship of normal and shear stress. This mechanism is dependent on plastic behavior of the soil mass. In terms of vertical and horizontal stresses on the body, shear is evaluated as: S13 = P1-P3 where S = shear stress on the plane inclined 45° to the planes of P, and P_ P = normal stress on the horizontal plane P_ = normal stress on any vertical plane The factor, K-., relates these stresses for soils, where: k0=p3vp1' where Kn = the coefficient of the earth mass at rest, and the primes indicate effective values of P, and P_ . That is, for a given soil, in-situ, a normal stress on the surface will result in a lateral stress which is Kn times the normal stress. Using the Mohr circle criteria, the shear induced within the soil will have a maximum value of: S = P_ (l-Kn)/2 max 1 O It has previously been assumed (Noorany and Seed, 1965) that for most cohesive soils, Kn is equal to 0.5. An objective of the present investi- gation was to determine if K remains constant for the various states of the sediments behavior. C. SIGNIFICANCE OF COHESION Most marine clays exhibit a resistance to shear which is, in part, independent of the normal load. This shear component is termed co- hesion. The value of cohesion depends strongly on water content and the constituent minerals, and to a lesser degree on particle size. The dependence of the latter factor is demonstrated in that while the vast majority of cohesive soils are fine grained, not all fine grained soils are cohesive (Karol, 1960). The constituents of marine soils are considered chiefly as complex silicates with some absorbed ions. Their chemical nature is such that a negative charge exists on the particle surfaces. In view of the polar nature of the water molecule, the hydrogen poles of the molecules are attracted to this negative charge. The water molecules attracted to the individual particles can be considered bound to the particle, but they also are attracted by other water molecules. If two adjacent soil particles are close enough, the bound particles of one particle are attracted by the bound water molecules of the adjacent particle, and thus the particles tend to remain stationary relative to each other. This attraction of bound water molecules is a molecular attraction, and is inversely 10 proportional to the distance between molecules squared. This molecular attraction can be seen as the force which opposes dislocation within the soil, independent of surface friction between soil particles. As it is a function of the distance between particles, those factors which vary distance will also cause variations of cohesion. Water content, therefore, is an important factor, as is particle orientation. The dis- tance is also effected by particle size and shape. These last two factors also effect the value of cohesive strength in that they determine the amount of surface area exposed, and therefore the amount of attraction between the particles and the water. The nature of cohesion as summarized above accounts for several of the properties noted for cohesive soils. The phenomenon of the sensi- tivity, or ratio of undisturbed strength to strength after some degree of reworking, can be explained in terms of particle orientation. In that the degree of cohesion is related to the distance between particles squared, those orientations that result in the lowest values of root mean square spacing have the highest cohesive strength. As most marine clay de- posits are evolved by flocculation and subsequent settling of suspended particles, the shape of the particles serves to dictate orientation. Most clay particles are either disc or needle shaped. The disc shape particles upon settling will normally be oriented with the larger dimensional planes horizontal. This orientation results in the lowest root mean square spacing. Reworking will tend to produce random orientation and thereby lower the cohesive strength. In the case of needle shaped 11 particles, the settling process produces some particle interlocking, which while not of the same nature, also gives an added apparent strength. The reworking process in this case decreases this interlocking tendency and therefore also decreases the apparent cohesive strength. The property of plasticity is also related to the nature of cohesive strength. Plasticity, or the ability to undergo large strains without rupture, is a property of only cohesive soils. If all strength was due to internal friction, then forces sufficient to. cause slippage would be suffi- cient to cause failure. If, however, the forces are sufficient only to cause some displacement within the mass, the bonding forces attributed to cohesion continue to give some strength. This strength will continue to prevent rupture until displacement has increased to the point where the root mean squared spacing is such that cohesive strength can no longer resist the imposed force. D. BASIC EXPERIMENTAL APPROACH As a result of the low strengths of the marine soils above the liquid limit, the most common testing procedure in use is the vane shear test (Minhugh, 1970). This test is conducted by submerging a multi- blade vane into the test sample and applying a measured torque. This technique determines only apparent cohesive strength of the soil, and makes no determination of the relationship of the normal and shear stresses. This relationship is important because under normal loading conditions, the load is applied so as to create a normal stress, but fail- ure occurs as a result of induced shear stress. 12 Another method used to determine shear strength is the "direct shear" test. This test measures shear strength on a predetermined plane under various normal loads. The major difficulty with this test is that it assumes that no preferred failure plane exists, and is an assumption perhaps false for most marine sediments. A second drawback is that the sample is frequently disturbed in the testing procedure, and any strength due to particle orientation is altered. Two other tests have been widely used for determining strength of clays, the tri-axial and the unconfined compression tests. These are considered most applicable in the plastic region of soil behavior (Bishop and Henkel, 1962). Both are considered indirect methods of determining shear strength; that is, the strength is determined by measuring the normal stresses and applying the results to established relationships. These procedures present two difficulties with regards to testing marine soils. First, their results depend on the use of the relationships developed from the theory of plasticity, and are hence valid only for plastic soils. Secondly, testing of weak, high water content marine soils is physically extremely difficult. Many marine soils in their natural state are too weak to be tested by these methods. In an attempt to analyze the internal stress relationship of high water content marine soils, thin-walled aluminum test cells were de- signed for use with the NPGS Unconfined Compression testing machine (Westfahl, 1970). The walls of the test cells allowed testing at water contents well above the liquid limit. The results of such tests 13 must be evaluated with regard to present understanding of mechanical behavior and the results of increased water content on the strength of clays . The test cells developed for this study consisted of thin-walled aluminum cylinders. The response of such cylinders to internal pres- sures is well known. By determining their response to loadings, the internal pressure can be evaluated. Given a cylinder of radius R, height H, and wall thickness t, it is possible to determine the response of the cylinder to an internal pressure p, by considering an incremental section of the cylinder, dH by t by RdG , as shown in Figure 2. FIGURE 2. INCREMENTAL SECTION OF TEST CELL The pressure acts normal to the surface and produces a net force in the R direction of p x RdG x dH. The cylinder responds to this pressure with d9 d9 an equal and opposite force of 2 x t x dH x sin ~ x P where — is the angle of application and P is the tensile stress acting tangenti- ally in the cylinder. If the pressure acts inside the cylinder over 14 a height of H while the total can height is H , then the results of integration can be shown to be: Pt = (pxRx Hr) /(t x H2) The distribution of stresses within the wails of the cylinder are also well known relationships. The ratios of circumferences and height to wall thickness allow the assumption of a two dimensional stress- strain distribution. The circumferential change in length per unit length, or tangential strain, s , is related to the tangential and longitudinal stresses by the equation: (Stippes et al, 1961) St= E V *V where E = Young's Modulous, P - tangential stress, P = longitudinal stress, and M = Poison's Ratio The analysis of the stress-strain relationship may be simplified by allowing the ends of the cylinder to move unrestrained, thereby support- ing no longitudinal stress. With PT equaling zero, and multiplying through by E, the equation, solved for P becomes: Pt = E x st Substituting this equation into the previously determined equation for tangential stress, and solving for internal pressure, p, it can be seen that P = (st x E x t x H2 ) / (R x Hi ) 15 Young's Modulous, E, is a constant for a given metal, and t, R, H , and H, are easily measured parameters. It is seen then that by deter- mining the tangential strain, the internal pressure can be evaluated. 16 II. TEST EQUIPMENT A. NPGS UNCONFINED COMPRESSION TESTING MACHINE The vertical stresses on the test samples were imposed, controlled, and recorded using the unconfined compression testing machine designed and assembled by Westfahl (1970). Figure 3 shows the assembled machine, with the aluminum test cell designed for this investigation installed. The major components of the test machine, in addition to the structural members, are the machine screw jactuator, variable speed motor, the motor speed control, and the force transducer. These are shown in Figures 4 and 5. The force on the test cell was imposed by driving the machine screw jactuator at low speed. The force was meas- ured by Daytronics Corporation equipment, the force transducer being a model 52-50-A, with power supplied by a Model 300 D Transducer amplifier-indicator. The force signals from the transducer were condi- tioned and amplified by a module in the amplifier-indicator. The condi- tioned output from the module was used as a variable input to an X-T recorder. B. TEST CELL EQUIPMENT The lateral pressures in the soil sample were monitored utilizing thin-walled cylinders and strain gage equipment. The cylinders were machined from 2025 aluminum. Of the various metals available, 17 FIGURE 3. NPGS UNCONFINED COMPRESSION TESTING MACHINE WITH ALUMINUM TEST CELL. 18 FIGURE 4. ELECTRIC MOTOR AND MACHINE SCREW JACTUATOR FOR UNCON- FINED COMPRESSION TESTING MACHINE. FIGURE 5. ELECTRIC MOTOR CONTROLLER AND FORCE TRANSDUCER USED IN INVESTIGATION. 19 aluminum gave the best ratio of tangential strain to internal pressure. Open ended cylinders were used to simplify loading and to negate the influence of longitudinal stress. The cells used in the tests had the following dimensions: Inside Radius = 0.937 inches Height = 5.00 inches Thickness = 0.020 inches End plugs were constructed for the cylinders using the same metal stock. The radius of the plugs was such as to allow minimum clearance between the plugs and the cell wall while allowing vertical movement of the plugs within the cells. Under loading conditions, the free movement prevented friction, which would have induced longitudinal stress within the cell walls. The minimum clearance was to make the cylinder water- tight. However, this proved impossible if free movement was to be in- sured. Therefore, round cork gaskets were made to fit between the end plugs and the sample. Lubricating the end plugs and gaskets with a petroleum jelly served to ensure both watertight seals, and free move- ment. A photograph of the test cells, end plugs and gaskets is included as Figure 6 . Tangential strain was measured by various types of SR-4 strain gages. These were foil-backed, temperature compensating gages. The variation of resistance of the strain gage due to strain was measured on a portable SR-4 type L strain gage indicator, shown in Figure 7. 20 X. FIGURE 6. TEST CELL WITH STRAIN GAGES ATTACHED, END PLUGS, CORK GASKET, AND SPACERS ARE ALSO SHOWN. 21 FIGURE 7. STRAIN GAGE INDICATOR USED IN INVESTIGATION, 22 C . AUXILIARY TEST EQUIPMENT To allow a more meaningful interpretation of test data, several auxiliary tests were performed on the samples. Water content deter- minations were made using an analytic balance accurate to within 0.01 gm, and a drying oven thermostatically controlled at 110 + 5 °C . Liquid limit tests were conducted using a mechanical liquid limit device and then conducting water content determinations in the standard manner. Periodic Bulk Wet Density determinations were made using the known volume of the test cells, and the balance described above. The balance was further used, in conjunction with an air comparison pycnometer, accurate to within 0.01 cc , for specific gravity of solids determination. Measurements of cylinder radius , thickness, and height, and sample height were made using calipers accurate to within 0.001 inches. 23 III. TEST PROCEDURE The tests in this investigation were conducted on samples of clay from Seal Beach Lagoon, California. Previous tests on these samples had been conducted by King (196 9). These samples had been stored since collection in an emersed condition. No drying had occurred, and the only deterioration apparent was in the form of rust from the storage containers. Water content of the stored clay was measured at 70%. To insure that results were representative of the general mass, and not a single sample, 14 samples were used during this investigation. It was realized that it would not be possible to find a homogeneous soil body exhibiting the wide range of water contents desired for testing. As a consequence, it was decided to use remolded samples, and to van/ the water content by allowing a fairly uniform and slow drying between test runs. The samples were remolded during the drying periods and this served to ensure satisfactorily uniform drying. Sufficient material was utilized for each sample to allow multiple tests on the sample even with some of the sample used after each test for water content measure- ment. Bulk Wet Density determinations were made periodically to ensure that all tests were conducted on fully saturated samples . Liquid limit tests were made on every other sample, and the dried samples from these tests were used for specific gravity determinations. This testing was done primarily to insure homogeneity. The liquid limit was evaluated as 55.0 ± 0.5%. 24 Each sample was removed from the storage container, and the con- tainer was then resealed to prevent drying. A portion of the removed sample was tested for water content, and the remainder of the sample was remolded in a large dish. The sample was then transferred to the test cell using a spatula, and again reworked to minimize the possibility of entrapped air. This was done by use of a column of 1/4-inch spacers inside the cylinder. One of the cork gaskets was placed on top of the spacers, and the cylinder was filled from. the gasket to the top. Several spacers were removed and then more sample was added. This was con- tinued until approximately 4 inches of sample was contained within the cylinder. The open end of the cylinder was then capped using a second gasket and an end plug. A slight pressure was exerted on the end plug to force the sample toward the end without a plug. The second end plug was then added. Slight pressure was then exerted for two reasons; first, to center the sample, and second, to ensure that both end plugs moved without friction within the cylinder walls. Figure 8 is a cross sectional drawing of the completed assembly ready for testing. The filled test cell was then installed in the unconfined compression machine as shown in Figure 9. Spacers were placed between the end plugs and lower platens to ensure free movement of the cylinder longitudinally. The upper platen was lowered so that the test cell was held in place, and the strain gages were connected to the strain gage indicator. The indicator was nulled and the force transducer and chart recorder were 25 TEST CELL ** H< END PLUG \ GASKET SAMPLE H, < R H FIGURE 8. TEST CELL CROSS SECTION 26 FIGURE 9. TEST CELL READY FOR TESTING 27 zeroed. The distance between the upper and lower platens was measured and from this, sample height was calculated and recorded. The motor for the machine screw jactuator was operated at a speed sufficiently slow to allow the operator to monitor the tangential strain. For most sample runs, a rate of less than 1% longitudinal strain per minute was used. Rates of up to 10% per minute were tried, with no apparent effect on the results. However, the slower rate proved more convenient for the test operations. The maximum load applied during the tests was in the range of 75 to 85 pounds. This insured that maxi- mum longitudinal strain on the sample was less than 2%, necessary to insure that stress relationships as determined were essentially indepen- dent of sample'distortion. The variables of interest were the normal force and the tangential strain. The method used to record these variables proved satisfactory. The strain gage indicator available had no output capability, so manual recording of strain was necessary. The output of the force transducer amplifier-indicator was used as the variable input to the X-T recorder. The force versus time plot thus obtained was modified to include indi- cations of strain increments. Increments of 10 micro-inches per inch of strain were indicated on the output force-time plots by alternately lifting and lowering the recorder pen. Figure 10 is a sample of one of the graphs thus obtained. Point O indicates zero conditions at start of test. Point A indicates 10 micro-inches per inch strain. Point B indi- cates pen lowered to signal 20 micro-inches. The break in the 28 FIGURE 10. FORCE VERSUS TIME OUTPUT PLOT, MODULATED TO INDICATE INCREMENTS OF STRAIN. 29 curve at Point C marks a change of scale from 0.2 lbs force per scale unit to 5 lbs per unit, and Point D represents a further scale change to 10 lbs per unit. After the maximum force for each run was reached, the screw drive was stopped, and total change of sample height was measured. All tests were conducted so that sample change of height was less than 2%. The force was then removed, the strain gages disconnected, and the sample extruded from the cell. The sample was placed in a drying dish, and a small portion was taken for a water content determination. A new sample was then placed within the test cell, and the previously tested sample allowed to dry. As stated previously, the samples were reworked during the drying process. Approximately 4 tests were made on each sample, with differences of at least 2% in water content in each subsequent run. The samples were discarded when it became apparent either that drying was not uniform or that the sample was no longer fully saturated . In the early stages of the testing, the assumption was made that below the liquid limit, the coefficient of Earth pressure at rest, Kq, would be 0.5, so samples were discarded when their water contents approached the liquid limit. However, during preliminary data reduction, it became apparent that this was not the case. Subsequent samples were therefore allowed to dry as far below this limit as possible. Three samples dried to water contents of about 4 5% before becoming unsaturated 30 IV. ANALYSIS OF DATA The output plots were reduced to a tabular notation of- tangential strain versus force. While the graphs of these functions were propor- tional to the desired P. versus P curves, their dependence upon sample height limited the utility. The determinations that were desired were the relationship of the vertical stress P. to the horizontal stress P. and the relationship of this to the water content. The pressure against the walls of the cylinder at any point equals the radial stress P of the soil column at that point. Remolding of the R sample eliminated any inhomogeneities within the column, so P is K considered equal to P . The earlier equation: s x E x t H p= -7— ij becomes: s x E x t x H P. = 3 r x H Using the fact that Ko " Vpi and recognizing that the normal stress P equals the normal force F divided by the area of application, an equation which gives K in terms of the measured variables is: 31 Ko = co (st/(F x V where co " cell constant, st = tangential strain, F = normal force, and Hl = sample height The values of Cq were obtained by periodic calibrations of the cylinders using water (Kq = 1) in place of the sample. Seven such calibrations were conducted and each gave a value of CQ = 1.58 + 0.04 The Naval Postgraduate School IBM 360 digital computer was used for the data reduction. The required variables and constants were used as an input for a program which solved for P. , P.,, and Kn . A table of normal force, tangential strain, P. , P , and K~ for each run was obtained. Eight runs were terminated either due to system malfunction or as a result of anomalous data. The tables for the 55 successful runs are included as Appendix A. The computer was also used to plot P. versus P_ for all tests. Figure 11 illustrates one such plot, with a best fit straight line. All 55 successful runs approximated straight lines for the range of interest. The slopes of these lines were evaluated as Kq for that particular run, and Kq versus water content was plotted for the test samples. Figure 12 is the final plot of Kq versus water content. 32 + + + + o [X. CD CD CM H r» + + + tr- + + oc ^ LlJ 21 OD ^ v: lj t; 2" Ft O 4 CI 1 I + » + C-3 stc ztc t-1: rv FIGURE 11. SAMPLE P VERSUS P GRAPH. X 0 33 •0.8 -■07 o " o ort o 8 °o o o o o o -o o 0.6 o o ■■0.5 ■•0.4 o o o -4£ &. 5 5 6 0 65 70 -+- WATER CONTENT (%) FIGURE 12. KQ VERSUS WATER CONTENT. 34 V. RESULTS For the entire range of water contents tested, from 45% to 71%, there appeared a strong dependence of Kq upon the water content. The value of liquid limit as measured in seven tests on samples was 55.1%. Further, Kq for a given water content was constant throughout the full range of forces applied. The position of the strain gages on the cans was moved from mid height as far as one inch below the top of the cyl- inder with no apparent effect on the results. The method used in these tests to determine the tangential strain appears to be the greatest short- coming of the procedure. The range of pressures was such that maxi- mum strain was less than 150 micro inches per inch. The accuracy of the strain gage indicator used was rated at — 0.5 micro inches. When considered in light of 10 micro inch intervals, this is not fully satis- factory. The initial objective of this work was to test the concept of stress measurement using confining cylinders. The relationship of normal to horizontal stress was evaluated at values well above the liquid limit. With this objective in mind the results were favorable. The question of the exact nature of soils above the liquid limit was answered to some degree. There is a marked plasticity exhibited even above the limit, while the change from liquid to plastic behavior below the limit is not as rapid as envisioned. This bi-state behavior of clays suggests that empirical solutions to strength problems are 35 required, and raises questions as to the applicability of testing based purely on a plastic behavior. The triaxial and unconfined compression tests are the major examples of indirect tests, and predictions of soil strength made from the results of these tests relate to plastic theory. This does not apply to non-cohesive sediments, as plasticity is a pro- perty only of cohesive soils. 36 VI. CONCLUSIONS A. KQ-WATER CONTENT RELATIONSHIP It is apparent from the results of this work that a dependence of Kq upon water content exists , though the degree of this dependence is not completely clear. It was initially assumed that the curve of Kq versus water content would be close to asymptotic to 0.5 below the liquid limit, and to 1.0 above the limit. A wide region of bi-state be- havior appears to exist, but definite boundaries of the bi-state behavior were not detected. However, some asymptotic behavior does appear to exist, as depicted in Figure 12. The behavior seen could be approxi- mated by either an arctan curve or one quadrant of a sine curve. This latter would support Jazy's approximation of (Jazy, 1944): K = 1 - sin f6' where o7 ' = effective or apparent angle of friction. Since cohesion be- comes more important in the shear problem, for higher water contents apparent $ will be some function of cohesive strength versus normal stress. The higher water contents result in greater inter-particle dis- tance, and therefore decreases cohesive strength. This decrease is proportional to the inverse of the square of the separation distance. The increase of spacing is a factor of water content, particle size, and orientation. The indeterminate nature of these variables indicates the necessity of empirical solution to the problem. 37 Combining the earlier stated equation of resultant shear and the modification of the Terzaghi-Hvorslev criterion, one arrives at the solution: P, = S x 2/(1 - K ) 1 max O max and for high water contents, since S = C , Pj = C x 2/(1 - K ) max As would be expected, these become indeterminate as K approaches 1.0. However, the immediate results of these tests that show non- unity values for K~ above the liquid limit indicate applicability within the ranges of water contents of most marine clays. B. CONFINED COMPRESSION TESTING The test cell approach allowed an examination of the high water content clays with regard to their internal stress distribution. Standard test methods have not satisfactorily determined these relationships. Direct methods of shear determination conducted on samples of higher water content measure only cohesive strength. Indirect methods are difficult because of the low degree of plasticity. Loads in actual appli- cations would be applied to the soils in the form of normal loads. Therefore, the resultant stresses of such loads are of interest and must be analyzed. New methods must be considered, in order to overcome the difficulties of dealing with low strength high water content marine clays. The solution may well be a test such as conducted in this study, 38 in conjunction with use of the vane shear to evaluate cohesive strength This test cell approach is not dependent upon single state behavior for validity, and so can be applied in the area of interest. It has served to more completely define the problem. 39 VII. RECOMMENDATIONS FOR FURTHER WORK The primary study recommended concerns the nature of the water within sediments. As a result of the test of this investigation, it is believed that some percentage of the water molecules is tightly bound to the soil particles. A complex test utilizing heavy water (D O) is suggested to determine if this is true. If bonding of the surface mole- cules is not strong enough to permanently affix the surface water, the particles would be more prone to move relative to one another and the mass would more closely approximate a water matrix with the particles floating in such a matrix. It is theorized, rather, that inter-particle attraction causes semi-permanent positioning of the soil particles. The tests of this study were conducted on a single clay type. It is recommended that further tests be conducted on various cohesive and non-cohesive soils, and further, that testing cover the full range from natural water content as low as the plastic limit. In conducting further tests, it is recommended that different sized containers be used, and that more refined strain measurement and recording systems be employed 40 APPENDIX A - TEST DATA RUN NUMBER 120801 WATER CONTENT 70.6 FORCE STRAIN PI P3 K 6.10 10.0 2.21 1.59 0.719 9. 10 20.0 3.29 3. 18 0.965 15.10 30.0 5.47 4.77 0.872 18.80 40.0 6.81 6.36 0.9 34 24.70 50.0 8.94 7.94 0.888 31.20 60.0 11 .29 9.5 3 0.844 39.20 70.0 14.19 11.12 0.784 46.80 80.0 16.94 12.71 0.750 52.20 90.0 18.90 14.30 0.757 58.60 100. 0 21.21 15. 89 0.749 62.90 110.0 22.77 17.48 0.768 68.80 120.0 24.91 19.07 0.766 73.20 130.0 26.50 20.65 0.779 RUN NUMBER 120802 WATER CONTENT 70.6 FORCE STRAIN PI P3 K 4.20 10.0 1.52 0. 14 0.095 9.60 20.0 3.48 0.29 0.0 83 12.80 30.0 4.63 0.43 0.094 18.20 40.0 6.59 0.58 0.088 25.10 50.0 9.09 0.72 0.079 31.60 60.0 11.44 0.87 0.076 35.80 70.0 12.96 1.01 0.078 40.90 80.0 14.81 1.16 0.078 46.00 90.0 16.65 1.30 0.078 51 .50 100.0 18.64 1.44 0.077 57.00 110.0 20.63 1.59 0.077 62.50 120.0 22.62 1.73 0.077 67.00 130.0 24.25 1.88 0.077 73.00 140.0 26.43 2.02 0.077 79.00 150.0 28.60 2.17 0.076 41 RUN NUMBER 120803 WATER CONTENT 68.5 FORCE STRAIN PI P3 K 4.00 10.0 1.45 1.63 1.129 8.00 20.0 2.90 3.27 1.129 15.50 30.0 5.61 4.90 0.874 23.00 40.0 8.33 6.54 0.785 28.00 50.0 10.14 8.17 0.806 33.00 60.0 11.95 9.81 0.821 38.50 70.0 13.94 11.44 0.821 44.00 80. 0 15.93 13.07 0.821 50.00 90.0 18.10 14.71 0.813 57.00 100.0 20.63 16.34 0.792 65.00 110.0 23.53 17.98 0.764 73.00 120.0 26.43 19.61 0.742 79.00 130.0 28.60 21.24 0.743 85.00 140.0 30.77 22.88 0.744 RUN NUMBER 120804 WATER CONTENT 68.5 FORCE STRAIN PI P3 K 5.00 10.0 1.81 1.66 0.916 9.90 20.0 3.58 3.32 0.925 17.50 30.0 6.33 4.97 0.785 25.00 40.0 9.05 6.63 0.733 32.50 50.0 11 .76 8.29 0.705 40.00 60.0 14.48 9.95 0.687 47.50 70.0 17.19 11.60 0.675 55.00 80.0 19.91 13.26 0.666 61.50 90.0 22.26 14.92 0.670 67.80 100.0 24.54 16.58 0.675 74.80 110.0 27.08 18.24 0.673 80.00 120.0 28.96 19.89 0.687 42 RUN NUMBER 120805 FORCE STRAIN WATER CONTENT 67.0 PI P3 K 5.50 10.0 1 .99 1.55 0.781 12.60 20.0 4.56 3.11 0.682 16.80 30.0 6.08 4.66 0.767 22.50 40.0 8.14 6.22 0.763 30.60 50.0 11.08 7.77 0.702 35.80 60.0 12.96 9.33 0.720 41.50 70.0 15.02 10.88 0.724 47.50 80.0 17.19 12.43 0.723 54.00 90.0 19.55 13.99 0.716 59.80 100.0 21.65 15.54 0.718 67.00 110.0 24.25 17. 10 0.705 72.50 120.0 26.24 18.65 0.711 79.00 130.0 28.60 20.21 0.707 RUN NUMBER 120806 WATER CONTENT 67.0 FORCE STRAIN PI P3 K 5.80 10.0 2.10 1.55 0.740 10.60 20.0 3.84 3.11 0.810 18.00 30.0 6.52 4.66 0.716 25.00 40.0 9.05 6.22 0.687 30.00 50.0 10.86 7.77 0.716 35.00 60.0 12.67 9.33 0.736 40.50 70.0 14.66 10.88 0.742 46.50 80. 0 16.83 12.43 0.739 52.30 90.0 18.93 13.99 0.739 58.00 100.0 21.00 15.54 0.740 63.50 110.0 22.99 17. 10 0.744 69.00 120.0 24.98 18.65 0.747 74.00 13.0.0 26.79 20.21 0.754 80.00 140.0 28.96 21.76 0.751 43 RUN NUMBER 120807 WATER CONTENT 67.0 FORCE STRAIN PI P3 K 4.50 10.0 1.63 1.39 0.852 9.00 20.0 3.26 2.78 0.852 16.50 30.0 5.97 4.16 0.697 24.50 40.0 8.87 5.55 0.626 30.00 50.0 10.86 6.94 0.639 35.50 60.0 12.85 8.33 0.648 40.00 70.0 14.48 9.72 0.671 44.60 80.0 16.15 11.11 0.688 49.00 90.0 17.74 12.49 0.704 54.5 0 100.0 19.73 13.88 0.704 60.00 110.0 21.72 15.27 0.703 65.00 120.0 23.53 16.66 0.708 70.00 130.0 25.34 18.05 0.712 76.00 140.0 27.51 19.44 0.706 PUN NUMBER 12080b FORCE STRAIN kATER CONTENT 65.0 PI P3 K 4.20 10.0 1.52 1.39 0.915 8.60 20.0 3.11 2.78 0.894 15.00 30.0 5.43 4.17 0.769 21.00 40.0 7.60 5.57 0.732 26.00 50.0 9.41 6.96 0.739 30.50 60.0 11.04 8.35 0.756 36.00 70.0 13.03 9.74 0.747 42.00 80.0 15.20 11.13 0.732 47.00 90.0 17.01 12.52 0.736 52.00 100.0 18.82 13.92 0.739 57.00 110.0 20.63 15.31 0.742 63.00 120.0 22.81 16.70 0.732 69.00 130.0 24.98 18.09 0.724 74.50 140.0 26.97 19.48 0.722 80.50 150.0 29.14 20.87 0.716 44 RUN NUMBER 120 809 FORCE STRAIN WATER CONTENT 65.0 PI P3 K 7.50 10.0 2.71 1.54 0.568 12.50 20.0 4.52 3.08 0.681 16.80 30.0 6.08 4.63 0.760 20.80 40.0 7.53 6.17 0.819 26.60 50.0 9.63 7.71 0.801 32.70 60.0 11.84 9.25 0.781 38.80 70.0 14.05 10.79 0.768 44.50 80.0 16.11 12.33 0.766 50.30 90.0 18.21 13.88 0.762 56.90 100.0 20.60 15.42 0.748 62.50 110.0 22.62 16.96 0.750 68.00 120.0 24.62 18.50 0.752 73.60 130.0 26.64 20.04 0.752 RUN NUMBER 120S10 WATER CONTENT 65.0 FORCE STRAIN PI P3 K 7.80 10.0 2.82 1.55 0.550 13.60 20.0 4.92 3.11 0.631 18.80 30.0 6.81 4.66 0.685 23.50 40.0 8.51 6.22 0.731 29.60 50.0 10.72 7.77 0.725 35.50 60.0 12.85 9.33 0.726 41.70 70.0 15.10 10.88 0.721 47.50 80.0 17.19 12.43 0.723 52.50 90.0 19.00 13.99 0.736 58.80 100.0 21.29 15.54 0.730 63.50 110.0 22.99 17. 10 0.744 70.60 120.0 25.56 18.65 0.730 75.80 130.0 27.44 20.21 0.736 81.50 140.0 29.50 21.76 0.738 45 RUN NUM3ER 120811 WATER CONTENT 65.0 FORCE STRAIN PI P3 K 11.00 10.0 3.98 2.01 0.504 18.50 20.0 6.70 4.01 0.599 26.00 30.0 9.41 6.02 0.640 32.00 40.0 11 .58 8.03 0.693 41.00 50.0 14.84 10.03 0.676 47.00 60.0 17.01 12.04 0.708 52.80 70.0 19.11 14.05 0.735 61.00 80.0 22.08 16.06 0.727 69.10 90.0 25.01 18.06 0.722 78.00 100.0 28.24 20.07 0.711 PUN NUMBER 120812 WATER CONTENT 63.0 FORCE STRAIN PI P3 K 9.90 10.0 3.58 2.27 0.633 15.50 20.0 5.61 4. 54 0.809 22.90 30.0 8.29 6.81 0.821 3^.80 40.0 11 .15 9.08 0.814 45.50 50.0 16.47 11.35 0.689 52.30 60.0 18.93 13.62 0.719 59.90 70.0 21.68 15.89 0.733 69.10 80.0 ' 25.01 18.16 0.726 77.50 90.0 28.05 20.43 0.728 46 RUN NUMBER 120814 FORCE STRAIN WATER CONTENT 59.0 PI P3 K 8.80 10.0 3.19 1.51 0.474 15.50 20.0 5.61 3.02 0.538 20.60 30.0 7.46 4.53 0.607 25.50 40.0 9.23 6.04 0.654 31.80 50.0 11.51 7.55 0.655 38.00 60.0 13.76 9.05 0.658 43.50 • 70.0 15.75 10.56 0.671 51. 50 80.0 18.64 12.07 0.648 59.00 90.0 21.36 13.58 0.636 65.50 100.0 23.71 15.09 0.636 72.00 110.0 26.06 16.60 0.637 78.00 120.0 28.24 18. 11 0.641 RUN NUMBER 120815 WATER CONTENT 59.0 FORCE STRAIN PI P3 K 8.20 10.0 2.97 1.52 0.511 15.00 20.0 5.43 3.03 0.559 20.60 30.0 7.46 4.55 0.610 26.00 40.0 9.41 6.07 0.645 32.50 50.0 11.76 7.59 0.645 38.50 60.0 13.94 9. 10 0.653 45.00 70.0 16.29 10.62 0.652 52.50 80.0 19.00 12.14 0.639 58.80 90.0 21.29 13.65 ^.641 65.50 100.0 2^."H ) 5 . 1 7 0 . 640 47 RUN NUMBER 120901 WATER CONTENT 54.4 FORCE STRAIN PI P3 K 11.00 10.0 3.98 1.31 0.330 17.00 20.0 6.15 2.63 0.427 23.10 30.0 8.36 3.94 0.472 28.50 40.0 10.32 5.26 0.510 34.00 50.0 12.31 6.57 0.534 40.00 60.0 14.48 7.89 0.545 45.80 70.0 16.58 9.20 0.555 52.00 80.0 18.82 10.52 0.559 58.50 90.0 21 .18 11.83 0.559 65.50 100.0 23.71 13. 15 0.555 RUN NUM8ER 120902 WATER CONTENT 54.4 FORCE STRAIN PI P3 K 11.80 10.0 4.27 1.32 0.309 20.80 20.0 7.53 2.64 0.351 26.00 30.0 9.41 3.96 0.421 31.50 40.0 11.40 5.28 0.463 37.50 50.0 13.57 6.60 0.4 87 43.00 60.0 15.57 7.93 0.509 48.00 70.0 17.38 9.25 0.532 53.50 80.0 19.37 10.57 0.546 60.00 90.0 21.72 11.89 0.547 65.50 100.0 23.71 13.21 0.557 71.50 110.0 25.88 14.53 0.561 76.50 120.0 27.69 15.85 0.572 48 N NUMBER 120903 WATER CONTENT 53.3 FORCE STRAIN PI P3 K 12.80 10.0 4.63 1.32 0.285 19.90 20.0 7.20 2.64 0.367 26.70 30.0 9.67 3.97 0.410 32.00 40.0 11.58 5.29 0.457 38.00 50.0 13.76 6.61 0.481 43.50 60.0 15.75 7.93 0.5 04 49.00 70.0 17.74 9.26 0.522 56.00 80.0 20.27 10.58 0.522 62.50 90.0 22.62 11.90 0.526 67.50 100.0 24.43 13.22 0.541 73.00 110.0 26.43 14.55 0.550 RUN NUMBER 120905 WATER CONTENT 50.4 FORCE STRAIN PI P3 K 15. 50 10.0 5.61 1.68 0.299 23.50 20.0 8.51 3.35 0.3 94 29.00 30.0 10.50 5.03 0.479 36.50 40.0 13.21 6.71 0.508 43.50 50.0 15.75 8. 39 0.533 54.50 60.0 19.73 10.06 0.510 63.00 70.0 22.81 11.74 0.515 70.00 80.0 25.34 13.42 0.530 78.00 90.0 28.24 15.10 0.535 49 RUN NUMBER 120906 WATER CONTENT 50.4 FORCE STRAIN PI P3 k 11.30 10.0 4.09 1.68 0.411 17.50 20.0 6.33 3.36 0.531 24.00 30.0 8.69 5.05 0.581 32.80 40.0 11.87 6.73 0.567 39.50 50.0 14.30 8.41 0.588 47.80 60.0 17.30 10.09 0.583 59.00 70.0 21.36 11.78 0.551 67.00 80.0 24.25 13.46 0.555 76.00 QQ.O 27.51 15.14 0.550 RUN NUMBER 120908 WATER CONTENT 57.6 FORCE STRAIN PI p3 K 9.00 10.0 3.26 1.25 0.3 85 16.50 20.0 5.97 2.51 0.420 22.50 30.0 8.14 3.76 0.^62 28.00 40.0 10.14 5.02 0.4 95 33.80 50.0 12.24 6. 27 0.513 39.00 60.0 14.12 7.53 0.533 44.50 70.0 16.11 8.78 0.545 49.60 80.0 17.96 10.03 0.559 55.00 90.0 19.91 11.29 0.567 60.80 100.0 22.01 12.54 0.570 65.50 110.0 23.71 13.80 0.582 71.00 120.0 25.70 15.05 0.586 50 RUN NUMBER 120909 WATER CONTENT 57.6 FORCE STRAIN PI P3 K 12.20 10.0 4.42 1.25 0.284 18.60 20.0 6.73 2.51 0.373 24.00 30.0 8.69 3.76 0.433 29.00 40.0 10.50 5.02 0.478 33.50 50.0 12.13 6.27 0.517 39.00 60.0 14.12 7.53 0.533 44.80 70.0 16.22 8.78 0. 541 50.20 80.0 18. 17 10.03 0.552 55.50 90.0 20.09 11.29 0.562 60.50 100.0 21.90 12.54 0.573 65.50 110.0 23.71 13.80 0.582 71.00 120.0 25.70 15.05 0.586 RUN NUMBER 121001 'WATER CONTENT 61.0 FORCE STRAIN PI P3 K 6.00 10.0 2.17 1.24 0.569 10.50 20.0 3.80 2.47 0.650 15.00 30.0 5.43 3.71 0.683 20.00 40.0 7.24 4.94 0.683 24.50 50.0 8.87 6.18 0.697 29.50 60.0 10.68 7.42 0.695 35.00 70.0 12.67 8.65 0.683 40.00 80.0 14*48 9.89 0.683 45.50 90.0 16.47 11.13 0.675 52.50 100.0 19.00 12.36 0.650 57.50 110.0 20.81 13.60 0.653 64.00 120.0 23.17 14.83 0.640 51 PUN NUMBER 121002 WATER CONTENT 61.0 FORCE STRAIN PI P3 K 7.00 10.0 2.53 1.28 0.506 12.50 20.0 4.52 2.57 0.567 18.00 30.0 6.52 3.85 0.591 23.00 40.0 8.33 5.13 0.617 26.50 50.0 9.59 6.42 0.669 32.50 60.0 11.76 7.70 0.654 37.50 70.0 13.57 8.98 0.662 42,50 80.0 15.38 10.27 0.667 47.50 90.0 17.19 11.55 0.672 54.00 100.0 19.55 12.83 0.656 59.00 110.0 21.36 14.12 0.661 64.50 120.0 23.35 15.40 0.660 70.00 130.0 25.34 16.68 0.658 75.00 140.0 27.15 17.97 0.662 80.00 150.0 28.96 19.25 0.665 RUN NUMBER 121003 WATER CONTENT 61.0 FORCE STRAIN PI P3 K 8.50 10.0 3.08 1.28 0.417 14.00 20.0 5.07 2.57 0.506 19.20 30.0 6.95 3.85 0.554 24.00 40.0 8.69 5.13 0.591 30.00 50.0 10.86 6.42 0.591 35.00 60.0 12.67 7.70 0.608 40.00 70.0 14.48 8.98 0.620 45.50 80.0 16.47 10.27 0.623 51.00 90.0 18.46 11.55 0.626 56.50 100.0 20.45 12.83 0.627 61.50 110.0 22.26 14.12 0.634 67.00 120.0 24.25 15.40 0.635 72.00 130.0 26.06 16.68 0.640 77.00 140.0 27.87 17.97 0.645 82.00 150.0 29.68 19.25 0.648 52 RUN NUMBER 121004 FORCE STRAIN WATER CONTENT 61.0 PI P3 K 8.50 10.0 3.08 1.42 0.462 15.20 20.0 5.50 2.84 0.517 21.00 30.0 7.60 4.27 0.561 26.00 40.0 9.41 5.69 0.604 31.20 50.0 11.29 7.11 0.630 36.50 60.0 13.21 8.53 0.646 42.50 70.0 15.38 9.95 0.647 48.50 80.0 17.56 11.38 0.648 53.50 90.0 19.37 12.80 0.661 58.00 100.0 21.00 14.22 0.677 63.00 110.0 22.81 15.64 0.686 68.50 120.0 24.80 17.06 0.688 N NUMBE R 121005 WATER CONTENT 59.3 FORCE STRAIN PI P3 K 7.20 10.0 2.61 1.42 0.546 13.50 20.0 4.89 2.85 0.583 20.00 30.0 7.24 4.27 0.590 25.40 40.0 9.19 5.70 0.619 31.00 50.0 11.22 7.12 0.634 36.50 60.0 13.21 8.54 0.647 42.50 70.0 15.38 9.97 0.648 48.00 80.0 17.38 11.39 0.656 53.20 90.0 19.26 12.81 0.665 57.50 100.0 20.81 14.24 0.684 64.00 110.0 23.17 15.66 0.676 69.50 120.0 25.16 17.09 0.679 74.50 130.0 26.97 18.51 0.686 79.00 140.0 28.60 19.93 0.697 53 PUN NUMBER 121006 WATER CONTENT 59.3 FORCE STRAIN PI P3 K 8.00 10.0 2.90 1.43 0.493 14.50 20.0 5.25 2.85 0.544 20.50 30.0 7.42 4.28 0.577 26.00 40.0 9.41 5.71 0.607 31.50 50.0 11.40 7.14 0.626 36.50 60.0 13.21 8.56 0.648 42.50 70.0 15.38 9.99 0.649 48.00 80.0 17.38 11.42 0.657 53.5 0 90.0 19.37 12.85 0.663 58.00 100.0 21.00 14.27 0.680 64.50 110.0 23.35 15.70 0.672 69.50 120.0 25.16 17.13 0.681 74.50 130.0 26.97 18. 56 0.688 79.50 140.0 28.78 19.98 0.694 RUN NUMBER 121007 WATER CONTENT 59.3 FORCE STRAIN PI P3 K 9.50 10.0 3.44 1.44 0.419 14.50 20.0 5.25 2.88 0.549 19.70 30.0 7.13 4.33 0.607 25.50 40.0 9.23 5.77 0.625 31.50 50.0 11.40 7.21 0.632 37.00 60.0 13.39 8.65 0.646 43.00 70.0 15.57 10.09 0.648 48.00 80.0 17.38 11.53 0.664 54.0 0 90.0 19.55 12.98 0.664 60.00 100.0 21.72 14.42 0.664 65.50 110.0 23.71 15. 86 0.669 70.20 120.0 25.41 17.30 0.681 54 RUN NUMBER 121008 WATER CONTENT 59.3 FORCE STRAIN PI P3 K 6.50 10.0 2.35 1.45 0.616 13.50 20.0 4.89 2.90 0.593 20.50 30.0 7.42 4.35 0.586 25.00 40.0 9.05 5.80 0.640 30.50 50.0 11.04 7.25 0.656 36.50 60.0 13.21 8.69 0.658 41.00 70.0 14.84 10.14 0.683 47.00 80.0 17.01 11.59 0.681 53.00 90.0 19.19 13.04 0.680 58.50 100.0 21.18 14.49 0.684 64.00 110.0 23.17 15.94 0.688 RUN NUMBER 121009 FORCE STRAIN WATER CONTENT 59.3 PI P3 K 10.50 10.0 3.80 1.45 0.382 16.50 20.0 5.97 2.91 0.486 23.00 30.0 8.33 4.36 0.523 29.50 40.0 10.68 5.81 0.544 35.00 50.0 12.67 7.26 0.573 40.00 60.0 14.48 8.72 0.602 46.00 70.0 16.65 10.17 0.611 51.00 80.0 18.46 11.62 0.630 56.50 90.0 20.45 13.08 0.639 62.00 100.0 22.44 14.53 0.647 68.00 110.0 24.62 15.98 0.649 55 RUN NUMBER 121010 WATER CONTENT 57.1 FORCE STRAIN PI P3 K 5.00 10.0 1.81 1.31 0.724 9.50 20.0 3.44 2.62 0.762 15.50 30.0 5.61 3.93 0.700 21.00 40.0 7.60 5.24 0.689 25.50 50.0 9.23 6.55 0.709 31.00 60.0 11.22 7. 86 0.700 36.50 70.0 13.21 9.17 0.694 43.00 80.0 15.57 10.48 0.673 49.00 90.0 17.74 11.79 0.665 55.00 100.0 19.91 13.10 0.658 60.50 110.0 21.90 14.41 0.658 65.00 120.0 23.53 15.72 0.668 RUN NUMBER 121011 FORCE STRAIN WATEk CONTENT 57.0 PI P3 K 6.50 10.0 2.35 1.31 0.558 11.50 20.0 4.16 2.63 0.631 18.50 30.0 6.70 3.94 0.588 25.00 40.0 9.05 5.25 0.5 80 30.00 50.0 10.86 6.56 0.604 34.80 60. 0 12.60 7.88 0.625 39.80 70.0 14.41 9. 19 0.638 45.00 80.0 16.29 10.50 0.645 50.00 90.0 18.10 11. 81 0.653 55.50 100.0 20.09 13.13 0.653 60.50 110.0 21.90 14.44 0.659 56 RUN NUMBER 121012 WATER CONTENT 57.0 FORCE STRAIN PI P3 K 10.00 10.0 3.62 1.32 0.363 16.00 20.0 5.79 2.63 0.454 20.50 30.0 7.42 3.95 0.532 26.50 40.0 9.59 5.26 0.549 32.50 50.0 11 .76 6.58 0.559 38.50 60.0 13.94 7.89 0.566 45.00 70.0 16.29 9.21 0.565 50.50 80.0 18.28 10.53 0.576 56.50 90.0 20.45 11.84 0.579 62.50 1 30.0 22.62 13.16 1 0.582 RUN NUMBER 121013 WATER CONTENT 67.0 FORCE STRAIN PI P3 K 4.20 10.0 1.52 1.50 0.986 9.50 20.0 3.44 3.00 0.871 1.5.00 30.0 5.43 4.50 0.3 28 20.00 40.0 7.24 5.99 0.328 27.50 50.0 9.95 7.49 0. 753 33.80 60.0 12.24 8.99 0.735 39.00 70.0 14.12 10.49 0.743 44.50 80.0 16.11 11.99 0.744 49.50 90.0 17.92 13.49 0.753 54.60 100.0 19.77 14.98 0.758 60.00 110.0 21 .72 16.48 0.759 65.00 120.0 23.53 17.98 0.764 • 70.00 130.0 25.34 19.48 0.769 75.00 140.0 27.15 20.98 0.773 57 RUN NUMBER 121014 WATER CONTENT 67.0 FORCE STRAIN PI P3 K 5.00 10.0 1.81 1.51 0.832 12.00 20.0 4.34 3.01 0.694 17.00 30.0 6.15 4.52 0.734 23.00 40.0 8.33 6.03 0.724 28.00 50.0 10.14 7.53 0.743 34.00 60.0 12.31 9.04 0.734 39.50 70.0 14.30 10.54 0.737 45.00 80.0 16.29 12.05 0.740 50.00 90.0 18.10 13.56 0.749 55.50 100.0 20.09 15.06 0.750 61.50 110.0 22.26 16.57 0.744 RUN NUMBER 10802 WATER CONTENT 62.3 FORCE STRAIN PI P3 K 4.90 10.0 1.77 1.29 0.730 9.90 20.0 3.58 2.59 0.7 23 16.00 30.0 5.79 3.88 0.671 21.20 40.0 7.67 5. 18 0.675 26.50 50.0 • 9.59 6.47 0.675 31.80 60.0 11.51 7.77 0.675 37.00 70.0 13.39 9.06 0.677 41.50 80.0 15.02 10.36 0.690 47.00 90.0 17.01 11.65 0.685 51.80 1 00.0 18.75 12.95 0.691 58 RUN NUMBER 11101 WATER CONTENT 68.0 FORCE STRAIN PI P3 K 9.60 10.0 3.48 1.29 0.370 13.00 20.0 4.71 2.57 0.546 18.00 30.0 6.52 3.86 0.592 23.80 40.0 8.62 5.14 0.597 28.60 50.0 10.35 6.43 0.621 32.30 60.0 11.69 7.71 0.660 37.60 70.0 13.61 9.00 0.661 40.70 80.0 14.73 10.28 0.698 45.00 90.0 16.29 11.57 0.710 50.50 100.0 18.28 12.85 0.703 RUN NUMBER 11201 WATER CONTENT 71.3 FORCE STRAIN PI P3 K 5.40 10.0 1.95 1.27 0.648 9.80 20.0 3.55 2.53 0.714 13.00 30.0 4.71 3.80 0.807 16.30 40.0 5.90 5.06 0.85 8 20.30 50.0 7.35 6.33 0.862 24.00 60.0 8.69 7.60 0.874 28.60 70.0 10.35 8. 86 0.856 33.50 80.0 12.13 10.13 0.835 38.60 90.0 13.97 11.40 0.816 42.70 100.0 15.46 12.66 0.819 59 RUN NUMBER 11202 WATER CONTENT 58.1 FORCE STRAIN PI P3 K 5.50 ICO 1 .99 1.32 0.665 11.50 20.0 4.16 2. 55 0.636 17.60 30.0 6.37 3.97 0.623 22.50 40.0 8.14 5.30 0.650 28.90 50.0 10.46 6.62 0.633 33.10 60.0 11.98 7.94 0.663 39.80 70.0 14.41 9.2 7 0.643 44.70 80.0 16.18 10.59 0.655 51.80 90.0 18.75 11.92 0.635 RUN M.J ■ : 11302 WATER CONTENT 66.3 « FORCE STRAIN PI P3 K . 7.90 10.0 2.86 1.49 0.521 13.80 20.0 5.00 2.98 0.596 19.30 30.0 6.99 4.47 0.640 2-4.10 40.0 8.72 5.96 0.683 28.60 50.0 10.35 7.45 0.719 33.80 60.0 12.24 8.94 0.730 38.90 70.0 14.08 10.43 0.740 44.40 80.0 16.07 11.92 0.741 5'. 00 90.0 18.10 13.41 0.741 55.80 100.0 20.20 14.89 0.737 60 RUN NUMBER 11303 WATER CONTENT 61.1 FORCE STRAIN PI P3 K 6.00 10.0 2.17 1.23 0.566 10.80 20.0 3.91 2.46 0.629 17.50 30.0 6.33 3.69 0.582 23.00 40.0 8.33 4.92 0.591 28.60 50.0 10.35 6. 15 0.594 34.00 60.0 12.31 7.38 0.600 39.50 70.0 14.30 8.61 0.602 44.50 80.0 16.11 9. 84 0.611 50.00 90.0 18.10 11.07 0.612 54.90 . 100.0 19.87 12.30 0.619 RUN NUMBER 11401 WATER CONTENT 55.4 FORCE STRAIN PI P3 K 13.00 10.0 4.71 1.26 0.26 8 19.60 20.0 7.10 2.53 0.356 28.00 30.0 10.14 3.79 0.374 34.00 40.0 12.31 5.05 0.410 39.00 50.0 14.12 6.31 0.447 44.5 0 60.0 16.11 7.58 0.470 50.60 70.0 18.32 8.84 0.4 83 55.90 80.0 20.24 10.10 0.499 61.20 90.0 22.15 11.36 0.513 67.00 100.0 24.2 5 12.63 0.521 73.00 110.0 26.43 13.89 0.5 26 77.80 120.0 28.16 15.15 0.538 61 RUN NUMBER 11402 WATER CONTENT 59.7 FORCE STRAIN PI P3 K 11.80 10.0 4.27 1.34 0.314 17.50 20.0 6.33 2.68 0.423 23.10 30.0 8.36 4.02 0.481 29.00 40.0 10.50 5.36 0.511 34.80 50.0 12.60 6.71 0.532 39.80 60.0 14.41 8.05 0.558 45.10 70.0 16.33 9.39 0.575 50.20 80.0 18.17 10.73 0.590 55.80 90.0 20.20 12.07 0.598 60.80 100.0 22.01 13.41 0.609 66.90 110.0 24.22 14.75 0.609 72.10 120.0 26.10 16.09 0.617 N NUMBER 11403 WATER CONTENT 55.8 FORCE STRAIN PI P3 K 14.00 10.0 5.07 1.26 0.248 21.80 20.0 7.89 2.51 0.318 27.60 30.0 9.99 3.77 0.377 33.20 40.0 12.02 5.02 0.418 39.60 50.0 14.34 6.23 0.438 44.60 60.0 16.15 7.53 0.467 49.80 70.0 18.03 8.79 0.488 54.00 80.0 19.55 10.05 0.514 62 RUN NUMBER 11404 WATER CONTENT 54.0 FORCE STRAIN PI P3 K 10.20 10.0 3.69 1.36 0.368 17.30 20.0 6.26 2.72 0.434 22.80 30.0 8.25 4.08 0.494 29.20 40.0 10.57 5.43 0.514 35.00 50.0 12.67 6.79 0.536 41.30 60.0 14.95 8.15 0.545 48.00 70.0 17.38 9.51 0.547 55.60 80.0 20.13 10.87 0.540 62.10 90.0 22.48 12.23 0.544 67.40 100.0 24.40 13.59 0.557 RUN NUMBER 11801 WATER CONTENT 53.8 FORCE STRAIN PI P3 K 5.50 10.0 1.99 1.27 0.637 11. .00 20.0 3.98 2.54 0.637 17.20 30.0 6.23 3.80 0.611 24.20 40.0 8.76 5.07 0.579 30.00 50.0 10.86 6.34 0.5 84 36. 10 60.0 13.07 7.61 0.582 42.10 70.0 15.24 8.88 0.583 47.00 80.0 17.01 10.15 0.596 53.00 90.0 19.19 11.41 0.595 60.50 100.0 21.90 12.68 0.579 67.00 110.0 24.25 13.95 0.575 73.20 120.0 26.50 15.22 0.574 63 RUN NUMBER 11902 WATER CONTENT 63.9 FORCE STRAIN PI P3 K 10.50 10.0 3.80 1.55 0.409 17.80 20.0 6.44 3. 11 0.482 24.50 30.0 8.87 4.66 0.526 30.30 40.0 10.97 6.2 2 0.567 36.50 50.0 13.21 7.77 0.588 41.60 60.0 15.06 9. 33 0.619 48.00 70.0 17.38 10.88 0.626 54.20 80.0 19.62 12.43 0.634 59.20 90.0 21.43 13.99 0.653 65.00 100.0 23.53 15.54 0.661 72.00 110.0 26.06 17.10 0.656 77.10 120.0 27.91 18.65 0.668 82.50 130.0 29.86 20.21 0.677 RUN NUMBER 11903 WATER CONTENT 52.9 FORCE STRAIN PI P3 K 8.80 10.0 3.19 1.32 0.416 13.90 20.0 5.03 2.65 0.526 23.80 30.0 8.62 3.97 0.461 27.80 40.0 10.06 5.30 0.5 26 33.60 50.0 12.16 6.62 0.544 39.60 60.0 14.34 7.94 0.554 46.00 70.0 16.65 9.27 0.557 51.00 80.0 18.46 10.59 0.574 56.50 90.0 20.45 11.92 0.583 63.00 100.0 22.81 13.24 0.581 68.60 110.0 24.83 14.56 0.586 75.50 120.0 27.33 15.89 0.581 81.60 130.0 29.54 17.21 0.583 85.00 140.0 30.77 18.54 0.602 64 RUN NUMBER 11904 WATER CONTENT 51.6 FORCE STRAIN PI P3 K 9.90 10.0 3.58 1.31 0.367 16.60 20.0 6.01 2.63 0.438 22.80 30.0 8.25 3.94 0.478 29.20 40.0 10.57 5.26 0.498 34.50 50.0 12.49 6.57 0.526 40.50 60.0 14.66 7.89 0.538 47.50 70.0 17.19 9.20 0.535 52.80 80.0 19.11 10.52 0.550 59.00 90.0 21.36 11.83 0.554 64.00 100.0 23.17 13.15 0.568 69.50 110.0 25.16 14.46 0.575 75.20 120.0 27.22 15.78 0.580 81.00 130.0 29.32 17.09 0.583 86.00 140.0 31.13 18.41 0.591 RUN NUMBER 12001 WATER CONTENT 45.4 FORCE STRAIN PI P3 K 9.10 10.0 3.29 1.37 0.417 15.20 20.0 5.50 2.75 0.500 22.30 30.0 8.07 4.12 0.511 29.20 40.0 10.57 5.50 0.520 35.50 50.0 12.85 6. 87 0.535 41.90 60.0 15.17 8.25 0.544 49.00 70.0 17.74 9.62 0.543 56.00 80.0 20.27 11.00 0. 543 65.20 90.0 23.60 12.37 0.524 74.50 100.0 26.97 13.75 0.510 65 RUN NUMBER 12002 WATER CONTENT 63.5 FORCE STRAIN PI P3 K 7.20 10.0 2.61 1.44 0.554 15.00 20.0 5.43 2.89 0.532 19.60 30.0 7.10 4.33 0.611 25.00 40.0 9.05 5.78 0.638 29.30 50.0 10.61 7.22 0.681 35.60 60.0 12.89 8.67 0.672 43.00 70.0 15.57 10. 11 0.650 49.30 80.0 17.85 11.55 0.647 54.50 90.0 19.73 13.00 0.659 60.00 100.0 21.72 14.44 0.665 66.00 110.0 23.89 15.89 0.665 71.60 120.0 25.92 17.33 0.669 77.10 130.0 27.91 18.78 0.673 PUN NUMBER 12101 WATER CONTENT 44.0 FORCE STRAIN PI P3 K 22.30 10.0 8.07 1.46 0. 180 29.00 20.0 10.50 2.91 0.277 36.50 30.0 13.21 4.37 0.330 43.20 40.0 15.64 5.82 0.372 52.20 50.0 18.90 7.28 0.385 59.60 60.0 21.58 8.73 0.405 67.00 70.0 24.25 10. 19 0.420 73.50 80.0 26.61 11.64 0.438 81.00 90.0 29.32 13. 10 0.447 86.00 100.0 31.13 14.55 0.467 66 N NUMBER 12102 WATER CGNTENT 6.1 FHRCE STRAIN PI P3 K 6.70 10.0 2.43 1.46 0.602 11.40 20.0 4.13 2.92 0.707 15.50 30.0 5.61 4.38 0.780 18.70 40.0 6.77 5.84 0.862 24.30 50.0 8.80 7.30 0.8 29 30.50 60.0 11.04 8.75 0.793 37.00 70.0 13.39 10.21 0.763 43.80 80.0 15.86 11.67 0.736 49.50 90.0 17.92 13.1-3 0.733 55.50 100.0 20.09 14.59 0.726 61.00 110.0 22.08 16.05 0.727 66.50 120.0 24.07 17.51 0.727 71.80 130.0 25.99 18.97 0.730 99.99 140.0 36.20 20.43 0.564 RUN NUMBER 12103 WATER CONTENT 62.0 FORCE STRAIN PI P3 K 6.50 10.0 2.35 1.30 0.551 13.30 20.0 4.81 2.59 0.539 19.00 30.0 6.88 3. 89 0.566 24.10 40.0 8.72 5. 19 0.595 28.60 50.0 10.35 6.48 0.626 33.80 60.0 12.24 7.78 0.636 40.10 70.0 14.52 9.08 0.625 44.50 80.0 16.11 10.38 0.644 49.50 90.0 17.92 11.67 0.651 55.00 100.0 19.91 12.97 0.651 60. 10 110.0 21.76 14.27 0.656 65.80 120.0 23.82 15.56 0.653 71.10 130.0 25.74 16. 86 0.655 76.2 0 140.0 27.58 18.16 0.658 82.00 150.0 29.68 19.45 0.655 67 RUN NUMBER 12104 WATER CONTENT 44.6 FORCE STRAIN PI P3 K 12.80 10.0 4.63 1.41 0.304 21.80 20.0 7.89 2.82 0.357 29.30 30.0 10.61 4.23 0.398 36.30 40.0 13.14 5.64 0.429 44.00 50.0 15.93 7.04 0.442 50. 10 60.0 18.14 8.45 0.466 57.00 70.0 20.63 9. 86 0.478 62.50 . 80.0 22.62 11.27 0.498 68 BIBLIOGRAPHY 1. Bishop, A. W. and Henkel, D. S. , Measurement of Soil Properties in the Triaxial Test, 2nd ed. , p. 4-32, Arnold, 1962. 2. Coulumb, C. A. , "Essai sur une Application des Regies de Maximis et Minimis a Quelques Problemes de Statique Relatifs a I 'Architecture," Mem. Div. Sav . , Academie des Sciences, Paris, 1776. 3. Harr, M. E. , Foundations of Theoretical Soil Mechanics, McGraw- Hill, 1962. 4 . Hough, B. K. , Basic Soils Engineering , 2nd ed. , Ronald, 1969 . 5. Hvorslev, M. J. , "Uder die Festigkeilseigenshaften Gestorter Bindiger Boden," Danmarks Naturvidenskabelige Sambund, Ingeniorvidenskalbelige Skrifter, Series A, No. 45, Copenhagen, 1937. 6. Jazy, J. , "The Coefficient of Earth Pressure at Rest" Journal of the Society of Hungarian Architects and Engineers, p. 355-358, Budapest, 1944. 7. Karol, R. H., Soils and Soils Engineering, p. 10-13, 72-77, Prentice Hall, 1960. 8. King, J. D. , The Drying of Marine Sediments for Water Content Determinations , M.S. Thesis, Naval Postgraduate School, 1969. 9. Minugh, E. M. , A Versatile Vane-Shear Apparatus , M.S. Thesis, Naval Postgraduate School, 1970. 10. Mohr, O. , Abhandlunger aus dem Gebiete der technischen Mechanik, 2nded., p. 192-235, Ernst, Berlin, 1914. 11. Noorany, I. , and Seed, H. B. , "In-Situ Strength Characteristics of Soft Clays ," Journal of Soil Mechanics and Foundations Division, ASCE, Vol. 91, No. SM2, p. 49-79, March 1965. 12. Stippes, M., et.al. , An Introduction to the Mechanics of Deform- able Bodies, p. 270-275, Merrill, 1961. 13. Westfahl, R. K. , An Unconfined Compression Testing Machine for Marine Sediments , M. S. Thesis, Naval Postgraduate School, 1970. 69 INITIAL DISTRIBUTION LIST No. Copies 1. Defense Documentation Center 2 Cameron Station Alexandria, Virginia 2. Library, Code 0212 2 Naval Postgraduate School Monterey, California 93940 3. Oceanographer of the Navy 1 The Madison Building 732 North Washington Street Alexandria, Virginia 22314 4. Professor R. J. Smith, Code 58Sj 3 Department of Oceanography Naval Postgraduate School Monterey, California 93940 5. LT Henry F. Schultz, USN 3 Patrol Squadron THIRTY ONE (VP-31) NAS Moffett Field, California 94035 6. Department of Oceanography, Code 58 3 Naval Postgraduate School Monterey, California 93940 7. Commander 10 Naval Facilities Engineering Command Code 03 Washington, D. C. 20390 70 Security Classification DOCUMENT CONTROL DATA -R&D [Security c las si I ication ol title, body of abstract and indexing annotntmn must be entered when the overall report is classified) I originating activity (Corporate author) Naval Postgraduate School Monterey, California 93940 2*. REPORT SECURITY CLASSIFICATION Unclassified 2b. GROUP 3 REPOR T TITLE Testing of High Water Content Cohesive Soils Using Thin-Walled Test Cells 4 DESCRIPTIVE NOTES (Type of report and. inclusi ve dates) Master's Thesis; March 1971 5 AUTHORlSI (First name, middle initial, last name) Henry Francis Schultz 6 REPOR T DATE March 1971 7«. TOTAL NO. OF PAGES 72 7b. NO. OF REFS 13 »a. CONTRACT OR GRANT NO 6. PROJEC T NO 9a. ORIGINATOR'S REPORT NUMBER(S) 96. OTHER REPORT NO(S) (Any other numbers that may be assigned this report) 10 DISTRIBUTION STATEMENT Approved for public release; distribution unlimited II. SUPPLEMENTARY 12. SPONSO RING Ml LI T AR Y ACTIVITY Naval Postgraduate School Monterey, California 13. ABSTRACT The concepts associated with the field of soils mechanics are now being applied to marine sediments. Because of the more complex nature of the mixture of fine mineral particles and sea water, some of these concepts do not always appear overly applicable. This is particularly true with regard to the deep sea clays. In view of their often very high water contents, a liquid behavior might well be assumed for many marine clays. The analytical methods of fluid mechanics do not satisfac- torily explain the low strengths that are found in these soils. Thin-walled test cylinders were devised to allow testing of cohesive soils at high water contents. Over 50 tests were made of a test sediment, the majority above the liquid limit, to study the relationship of plasticity to water content. The results show that the gradation from liquid to plastic behavior encompasses a much wider range of water contents than previously considered. DD FOR- I47O I NOV 65 I "T / *J S/N 0101 -807-681 1 (PAGE 1) 71 Security Classification i-31408 Security Classification KEY WORDS L I N M A Sediments Cohesive Marine Soils Water Content Plasticity of Marine Soils Coefficient of Earth Pressure at Rest Variation of Strength Characteristics with Water Content Liquid Limit Bi-state Behavior DD FORM I NOV 68 1473 BACK S/N Ot 01 -807-682 1 72 Security Classification a - 3 1 4 o 9 Thesis 126623 S36<5 Schultz c.l Testing of high water content cohesive soils using thin-walled test eel Is. 1266? Schultz Testing of high water content cohesive soils using thin-walled test eel Is. thesS365 . Testing of high water content cohes ve s 3 2768 002 00058 0 DUDLEY KNOX LIBRARY