Anisotropic Hardening Rule for Presheared Clay under a Constant Mean-Stress Condition

Abstract

This paper suggests that the isotropic hardening rule with a modified hardening parameter can be used to simulate anisotropic hardening behavior from both theoretical and experimental viewpoints. It is believed that the isotropic hardening rule cannot simulate anisotropic hardening behavior mainly because its yield function is expressed in terms of the principal stresses and its hardening parameter is expressed in terms of the principal plastic strains. Contrary to this belief, the first part of this paper theoretically suggests that the isotropic hardening rule with a modified hardening parameter, expressed in terms of the plastic strains in the coordinate system defined by the principal stress axes, can simulate anisotropic hardening behavior. In the second part of this paper, it is experimentally shown that the isotropic hardening rule with the modified hardening parameter can simulate the actual anisotropic hardening behavior of presheared clay. The second part also discusses the microscopic mechanism of the hardening for the presheared clay with reference to the isotropic hardening rule with the modified hardening parameter.