Use of hyper-elasticity in anisotropic clay plasticity models

In conventional elastic-plastic constitutive models for clays, elastic strains are usually calculated by isotropic hypo-elastic models. However, this class of elasticity has two major deficiencies: (a) it ignores the influence of shear stress-induced anisotropy and; (b) it does not conserve energy. Another class of the elasticity theory, the so-called hyper-elasticity theory, is capable of eliminating both deficiencies simultaneously. In this study, constitutive equations of a recently proposed elastic-plastic platform for clays named SANICLAY are generalized in order to enable it to consider the possibility of the anisotropic response in the elastic domain. The generalized formulation allows shear-volumetric coupling not existing in the basic platform. Then, the elastic moduli obtained from a hyper-elastic model are implemented within the generalized SANICLAY formulation. The refined model predictions are directly compared with the experimental data of various clays. It is shown that more realistic stress paths are achieved from the refined model.