STRAIN LOCALIZATION ANALYSIS OF ANISOTROPIC SANDS BASED ON NON-COAXIAL THEORY

Aiming at the shortage of strain localization analysis on anisotropic sand, a non-coaxial theory was employed to improve constitutive model. The isotropy assumption in traditional plastic potential theory caused deficiencies that constitutive model can not describe non-coaxial features and can not give a better description of stress-induced anisotropy. To overcome such deficiencies, a three-dimensional non-coaxial critical state constitutive model for anisotropy sand is proposed with introduction of non-coaxial plasticity theory. In the view of the geometric relationship of micro fabric and stress state, the improved model can describe variation of sand state under the principal stress axes rotation condition, while the dilatancy and hardening law of model is a function of sand state. After amended with non-coaxial plasticity theory, the model can describe the non-coaxial features and stress-induced anisotropy, and the model with bifurcation theory can analyze the strain localization of anisotropy sand under different deposition angle and confining pressure condition. The improved model is verified against the results of simple shear and plane strain tests for Toyoura sand.