A Bounding Surface Viscoplastic Constitutive Model for Unsaturated Soils

摘要

A viscoplastic constitutive model for describing the time-dependent stress-strain behaviour of unsaturated geomaterials is presented. The proposed model is formulated within the framework of viscoplastic consistency and the bounding surface plasticity model. The model provides a continuous transition from rate-independent plasticity to rate-dependent viscoplasticity. The hardening parameter representing the size of the bounding surface is defined as a function of viscoplastic strain, viscoplastic strain rate, and suction. The suction hardening effect is described using the coupled influence approach where suction has a multiplicative effect to the viscoplastic volumetric hardening. Numerical results are presented to demonstrate the capability of the proposed model in simulating the behaviour of saturated and unsaturated geomaterials.