The ultimate bearing capacity of the base of shallow or deep foundations in saturated clays is studied using the method of characteristics. The undrained cohesion of the clay is considered to be anisotropic and to increase linearly with the depth below ground surface. Values of the bearing capacity factor, N_c, are presented in terms of the non-dimensional depth of foundation, the inclination of the equivalent free surface to the horizontal, and the parameters defining the anisotropy and the nonhomogeneity of the soil. It is found that, when the vertical strength is more than horizontal strength, lower values of N_c than those for the isotropic case are obtained. Also substantial increase in the values of N_c are found in the case where cohesion increases with depth, as compared to the case of constant cohesion with depth. Further, it is observed that the value of N_q, in the case of an anisotropic and nonhomogeneous medium, may be taken equal to unity without much error.

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The effect of initial structure on the residual shear strength of a saturated kaolinite clay is studied by using reversal-shear box technique. An attempt has been made to study the variation of structure with deformation by employing Direct Current conductivity (σ_s) dispersion characteristics. Residual strength is found to be practically independent of the initial structure for a given effective normal pressure (σ') and so also the shrinkage ratio. The conductivity reduced with increase in deformation and constancy attained when the total deformation reached the residual state. There is no significant variation in the strength ratio (tan φ'/tan φ'_r) and the conductivity ratio (σ_s initial/σ_s at residual) for a given initial structure.

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The purpose of this paper is to derive, as a basis of the finite element method, a generalized variational principle for consolidation under the following assumptions : Soil is inhomogeneous, anisotropically elastic with respect to effective stress, and saturated by incompressible water; deformation of soil does not depend on pore water pressure but on effective stress; water flows through soil according to Darcy's law. The paper is of theoretical nature.The derived variational principle which is equivalent to the governing equations in consolidation problems comprises six independent and piecewise continuous fields of displacement of soil skeleton, strain of soil skeleton, effective stress, water head, hydraulic gradient, and velocity of water relative to soil. The principle is so general that the already published variational principles for consolidation can be derived by setting some of the governing equations as side conditions. Furthermore, by making arbitrary sets of the governing equations subsidiary and boundary conditions, various variational principles can be developed, some of which may be useful for deriving effective finite element methods by application of the direct method.

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The purpose of this paper is to develop a finite element method for consolidation following undrained deformation under the following assumptions : Soil is inhomogeneous, anisotropically elastic with respect to the effective stress, and saturated by incompressible water; deformation of soil does not depend on pore water pressure but on the effective stress; water flows through soil according to Darcy's law. The paper is of a theoretical nature.The finite element method previously developed by Sandhu and Wilson (1969) and Yokoo, Yamagata, and Nagaoka (1971) is shown to be inapplicable to problems of consolidation following undrained deformation because of the inherent continuity requirement of water head. A new variational principle for consolidation is derived in which water head may be piecewise continuous, and the finite element technique is applied to the principle in order to develop an effective numerical method for the problems.

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This paper presents a quantitative method of organizing field observations concerning liquefaction and non-liquefaction during actual earthquakes. The ratio τ_c/σ^^-_V is evaluated for 13 sites affected by 8 earthquakes and plotted against relative density (τ_c is the average peak dynamic stress during the earthquake, and σ^^-_V is the vertical effective overburden stress, both evaluated at the critical depth). The effect of the duration of shaking is considered by means of a correction to τ_c/σ^^-_V. For recent fluvial deposits and uncompacted hydraulic fills, the critical level of τ_c/σ^^-_V for fine sands is about 0.15. This result is in reasonable agreement with results from laboratory investigation. More evidence is required concerning coarser and denser granular deposits.

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