Deformation and strength of clay under triaxial and torsional shear

Numerical predictions of the boundary value problems in solid mechanics by finite element technique have been utilizing constitutive equations of the constituent materials, which must incorporate the characteristic features of the material behavior for the realistic predictions. To this premises, a generalized elastoplastic model for clay has been devised which can simulate the strength, dilatancy and stress induced anisotropy characteristics of normally consolidated clay under generalized three dimensional monotonic loading conditions. This model utilizes an unconventional stress parameter t(ij) (called modified stress tensor), to consider the effect of intermediate principal stress on the direction of plastic flow and the strength of clay. Also, it is suggested that only part of the plastic strain increment vector satisfies now rule and the remaining part is linked with the increase of normal stress. Soil parameters to simulate normally consolidated day behavior are as many as well known Cam-clay model and easily determined from triaxial tests. Verification of the model is then made by analyzing several triaxial and torsional tests on laboratory reconstituted Fujinomori clay.