On the Modeling of Anisotropy and Destructuration of Shanghai Soft Clay

Abstract

The aim of this paper is to constitute a simple anisotropic elasto-plastic model that can predict the mechanical behavior of saturated structured soils. Undrained triaxial tests and drained stress probe tests under isotropic and anisotropic consolidation modes were performed on natural undisturbed samples of Shanghai soft clay to study the yielding characteristic. The effect of damage to structure caused by accumulated plastic strain is modeled with an inner variable that allows the size of the bounding surface to decay with plastic deformations. An anisotropic tensor and rotational hardening law were introduced to reflect the initial anisotropy and the evolution of anisotropy. Combined with the isotropic hardening rule, rotational hardening rule and degradation law of structure were incorporated into the bounding surface formulation with an associated flow rule. Validity of the model was verified by the undrained isotropic and anisotropic triaxial test results for Shanghai soft clay. The effects of stress anisotropy and loss of structure were well captured by the model.