ABSTRACT
The features of a model for the cyclic stress-strain behaviour of cohesive soil are explained and the implementation in FLAC described. The model is formulated within the framework of critical state soil mechanics. However, unlike the classical critical state models, Cam clay and modified Cam clay, this model has inelastic behaviour for overconsolidated soil. The particular version of the model implemented herein is for a lightly overconsolidated soil, which deforms in an undrained manner at constant mean principal effective stress. With the addition of small-strain elastic shear behaviour the model is shown to represent well the degradation, with shear strain amplitude, in the apparent shear modulus and equivalent viscous damping ratio; aspects of soil behaviour so important in earthquake geotechnical engineering. Also, as the number of soil parameters needed to drive the model are few and well understood, it is a potentially useful tool for investigating the general features of solutions to boundary value problems in soil dynamics. The results of applying the model to two boundary value problems — the bearing capacity of a shallow foundation on saturated clay and the propagation of nonlinear shear waves — are presented in the paper.
