Bounding surface plasticity model for structured clays using disturbed state concept-based hardening variables

Under the framework of bounding surface plasticity and critical state concept, by introducing the disturbed state concept for hardening variables of elastic behavior, structured yield surface, structured bonding adhesive stress and surface anisotropy, an elastoplastic model for structured clays is proposed. First, three structural disturbance degrees are defined to describe the disturbances of soils due to plastic strains to the size of yield surface, the adhesive stress and the yield surface anisotropy. The elastic law is also enhanced by considering anisotropy and disturbance. The model is then used to simulate the oedometer tests and undrained triaxial compression tests on two typical structured clays, Shanghai clay and Vallericca stiff clay. Finally, implementing the proposed model into a finite difference code as a user defined model, a biaxial shearing test is carried out to show the model ability in describing the development of structural disturbance degrees and its distributions in soils caused by plastic straining.