Simulation of the Cyclic Response of Anisotropic Clay through Bounding Surface Viscoplasticity

ABSTRACT: In this study, a recently developed framework referred to as bounding surface elasto-viscoplasticity (BS-EVP) is used to combine bounding surface concepts and the Perzyna’s overstress theory, thus enabling the simulation of rate effects for general degrees of overconsolidation. At variance with previous analyses, the model proposed here suppresses the hypothesis of isotropy and enables the simulation of fabric effects through rotational hardening. For this purpose, the SANICLAY model is recast in light of the BS-EVP framework by enabling the growth of the overstress and the consequent accumulation of viscous strain within the bounding surface. It is shown that the resulting constitutive model captures the dependence of the undrained strength of clays on the loading rates. Additionally, by employing a proper repositioning of the projection center and a hybrid flow rule, the performance of the model is improved to make it a robust model for cyclic loading applications and cyclic softening analysis.