A computer program TRUBAL was used to study fabric and shear modulus for sphere assemblies. It was shown by comparison with the experimental results that TRUBAL is able to describe the behavior of granular material qualitatively. The shear modulus was found to have a close relationship with the coordination number. During shear deformation, the coordination number decreased and the anisotropic fabric built up in the major principal stress direction, the sample became less rigid and its shear modulus decreased. After a cycle of loading and unloading, there was a net loss in coordination number and some remaining anisotropic fabric. This was also reflected in a decrease in the shear modulus. The isotropic fabric seems to have the highest coordination number. There is no unique relationship existing between the fabric and the stress or the fabric and the strain. The change of fabric appears after the change of stress takes place but it is ahead of the change of strain.

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A generalized three-dimensional constitutive model for isotropic cohesive soils, based on the concept of the bounding surface in stress space, is developed within the framework of coupled elastoplasticity-viscoplasticity and critical state soil mechanics. The prominent feature of the bounding surface concept is the fact that inelastic deformations can occur for stress points within the bounding surface. The consideration of viscoplastic characteristics sets the current model apart from previous bounding surface formulations for soils, and introduces rate and time effects. The coupling between plasticity and viscoplasticity for stress states within the bounding surface differentiates the present work from the classical formulation of pure viscoplasticity (no coupling), or from formulations involving plasticity and viscoplasticity with a yield surface (coupling only for states on the yield surface). General incremental constitutive relations applicable to cohesive soils are developed and suitably specialized for isotropic cohesive soils. A minimum number of parameters are introduced and a procedure for their determination is outlined. The predictive capabilities of the model are treated in a companion paper.

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Verification analyses associated with the elastoplastic-viscoplastic bounding surface model for isotropic cohesive soils, which was developed in an earlier paper, are presented. Following a brief overview of its theoretical aspects and numerical implementation, the simulative and predictive capabilities of this model are described. It is shown that the model can realistically simulate and predict drained and undrained creep and stress relaxation, strain rate effects, and secondary consolidation.

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The performance of driven and buried rigid model piles and small pile groups in homogeneous and two-layered sand composed of loose and dense layer combinations of different thickness has been investigated. The resistance developed of piles subjected to vertical, inclined and horizontal loads is compared with value estimated by theoretical or semi-empirical methods. Inclination factors have been determined for single driven piles and semi-empirical relations have been established to evaluate them in layered sand. Group efficiencies of driven and buried piles have been determined and compared. Finally, ultimate load ratios have been established to compare the resistance developed of buried piles against that of driven piles.

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The original Drnevich Resonant Column apparatus has been designed for testing cylindrical soil specimen with maximum longitudinal and torsional stiffnesses corresponding to approximate resonant frequencies 285 Hz and 318 Hz respectively. This apparatus has been modified successfully and its stiffness has been increased to over threefold in the longitudinal vibratory mode and at least twofold in the torsional vibratory mode. Monterey No. O sand samples prepared at approximate relative densities 43% and 60% were tested with the original and the modified apparatus in the range of effective confining pressures from 49 kPa to 588 kPa. Measurement of dynamic moduli values measured with the original apparatus were up to 23% higher, and damping values up to five times higher than those measured by the modified apparatus.

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Failure modes of embankments or slopes consisting of saturated cohesionless soils during earthquakes may be classified into two types, the one involving a limited amount of permanent deformation such as settlements or lateral bulging on the order of tens of centimeter to meters, and the other in which complete slumping or flow of materials takes place through distances of tens of meters. Associated with seismic risk evaluation of embankments, there are many cases where the occurrence of limited deformation is tolerated but the flow type of failure is never permissible. In such a case, a methodology becomes necessary for evaluating the safety of embankments against the flow type of failure, once it occurs. Post-earthquake stability analysis in which the conventional analysis is made by employing residual strength or steady-state strength of soils is used for this purpose. However, accurate evaluation of in-situ residual strength is a difficult task particularly for cohesionless soils. Thus, it would appear useful if estimates of the residual strength can be made based on the back analysis of several embankments that have suffered the flow type failure during past earthquakes. In the present study, slope stability analyses were made for several earthquake-damaged embankments and tailings dams composed of silty sands or sandy silts to back-calculate the value of residual strength. The ground conditions at the failure sites were investigated by means of the Dutch cone penetration test or by the Swedish cone test. By comparing the values of the back-calculated residual strength with those of the cone resistance, empirical correlations between them are obtained which may be used in turn for the evaluation of residual strength of similar soils on other sites.

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The bearing capacity and compressibility of a calcareous sand were examined by drained triaxial compression tests and laboratory model tests on strip footings 51mm by 305mm. The tests were carried out on two sands-a calcareous sand having a carbonate content of 18% and a clean sand obtained by washing the calcareous sand with Hydrochloric Acid (HCI) and water. All tests were performed at a relative density of 66%. The results indicate increased compressibility and no change in the peak strength parameters due to the presence of carbonates. The bearing capacity of the calcareous sand was smaller than that of the clean silica sand. Various methods of analysis were discussed to account for the effect of compressibility on bearing capacity.

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In order to accurately determine the relationships between a mechanical property and some physical properties in both natural and artificially mixed cohesive soils, multiple regression analysis was performed. In this paper, two kinds of regression models representing the shear strength of soils are examined. The first model is based on the Atterberg limit and the second is based on the Cam-Clay model. The concept of this study is that the mechanical properties of the soils are characterized by soil types and soil states. The following conclusions were obtained : (1) Both regression models established for the shear strength of soils are not only found to be valid for the unconfined compressive strength, but also for the modulus of deformation and consolidation yield stress. (2) The validity of the concept employed here can be quantitatively proved by multiple regression analysis. (3) In a fully saturated soil, the correlation between the two regression models can be found both by statistical analysis and by theoretical examination. (4) The regression equations are obtained in good predictive accuracy for unconfined compressive strength, the modulus of deformation, consolidation yield stress and compression index.

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Limiting equilibrium state of saturated soils is solved taking into account drainage conditions during loading stage before reaching limit state. In analysis procedure, non-dilatant characteristics are assumed at limit state and then the failure problem discussed in the present study is concerned with normally consolidated and/or lightly overconsolidated soils. When solving statically indeterminate limiting equilibrium state one needs constitutive relations at limit state. In saturated soils, however, since the constitutive relations are generally expressed in terms of effective stresses, an additional field equation is required in order to link a velocity field to a pore pressure field. Therefore the problem should be solved as a coupling problem between these two fields. Two distinct types are discussed, one is undrained problem and the other, fully drained problem. Topics covered in the present study are as follows : (1) Undrained bearing capacity and excavation stability of soft clays, (2) Bearing capacity under partly drained and/or partly swelling condition, (3) Comparison between rapid loading condition and undrained condition, and (4) Seepage failure of loose sandy soils under fully drained condition.

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The pore fluid of marine sediments contains various salts that are in solution in water. Frequently, however, the existence of salts is not considered when utilizing the concepts of water content and void ratio. In this note, expressions for the contents of water and pore fluid and the void ratio for saturated marine sediments are derived in terms of the 'water content' in which the salinity is not taken into account. The water and pore fluid contents and void ratio calculated with ordinary values of the 'water content' and the salinity are presented. It is demonstrated that the water content, pore fluid content and the void ratio would be underestimated by the order of 5% unless the salinity is taken into account.

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This paper investigates the fracturing phenomena in sandy as well as cohesive soil caused by injecting viscous materials such as the mortar. The fracturing pressure generally increases as the flow value F of injection material increases. In cohesive soils, the fracturing pressure P_f is equal to the cavity expansion pressure P_u (Vesic, 1972)of cohesive soils, irrespective of the value of F when F is more than 30 sec. This is because it is more difficult to mobilize the wedge action as the viscosity of injection materials increases. On the other hand, in sandy soils, the effect of flow value F on the fracturing pressure P_f becomes smaller as the permeability of sand increases. The fracturing pressure P_f' of sand of high permeability is equal to the cavity expansion pressure P_u' of sand soil, irrespective of the value of F.

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Recently as the increase of the execution of work for the educational town engineering, the number of the underground constructions have been greatly increased. These constuructions are mostly done by making narrow ditches. Although, when they are paved again after the work, enough rolling compaction is required, it is lacking due to the restricted time and the space. Thus in many cases, after the surface treatment with asphalt mixture, they are overlaid waiting the consolidation settlement. To gain a sufficient rolling compaction the lime stabilization is applied in the refilling soil, and so the good effect has been achieved. This way has made good results, so far. But due to the life limit of the underground installments when a redigging is necessary, it is pointed out that there remainds the difficulty of redigging. To solve these difficulties, QCB as a treatment agent has been developed, The use of this agent increases the internal inflation in the filling soil and as the result redigging can be done easily. Not only that, when this agent is used in place of the quick lime in the lime piling which is used as the stabilization for the deepseated ground, bearing capacity of the mixed soil of both soft soil and the pile and better soil strength constant are improved, but also early bearing capacity and shear stress of the pile, which could not be expected from formal quick lime piling, can be obtained.

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This paper focuses on an extension of the log-spiral analysis of bearing capacity that has been presented in the authors' previous work for strip foundations placed on the level ground, to those on the top of slopes. Comparisons are made with other analytical and experimental results to examine applicability of the method to practical problems. It is revealed that the log-spiral analysis somewhat overestimates bearing capacity values as compared to other solutions, the errors involved being around 20 percent at maximum and varying sensitively to the angle of internal friction and slope inclination. Also noticed is a relatively good correspondence with experimental results, especially with model tests on clay (φ=0), on both the ultimate bearing capacity and the shape of sliding surfaces.

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High-quality undisturbed samples of sand that had been compacted by a vibratory sand compaction pile method were obtained by in situ freezing. Undrained cyclic triaxial tests were conducted on specimens prepared from the samples after they had been thawed, saturated and consolidated. The relationship between the liquefaction resistance of the specimens and the SPT N-values corrected for a vertical effective stress of 1 kgf/cm² (98 kPa), N₁, is consistent with that for natural deposits of clean sands, over a range of N₁ between 21 and 28. It is concluded, therefore, that the liquefaction resistance of compacted sands can be evaluated on the basis of N₁ using the relationship established for natural sand deposits.

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