Modeling Liquefaction-Induced Large Deformation of Sand Incorporating the Effects of Fabric Anisotropy Evolution

Abstract

Previous studies based on the discrete-element method have pointed out that the evolution of fabric anisotropy plays a significant role in liquefaction, but current constitutive models of sand considering fabric anisotropy effects are not proficient at simulating the evolution of fabric anisotropy and its effect on liquefaction during cyclic undrained loading. This study proposes a unified elastoplastic model of sand to model the liquefaction-induced large deformation by incorporating the effects of fabric anisotropy evolution. The key point is to relate the evolution of fabric anisotropy to the octahedral plastic shear strain and to propose a new expression of the dilatancy coefficient considering fabric effects. In addition, an expression of the critical state line with relative density is presented, with a modified mapping rule based on bounding-surface theory for cyclic loading, and Bouc–Wen type elastoplasticity is introduced with a hardening exponent determined by fabric anisotropy. Moreover, an explicit adaptive Runge–Kutta–Fehlberg algorithm is adopted for numerical stability in the model implementation. The capacity of the proposed model to simulate the behavior of sand under monotonic and cyclic loading was validated against experimental data for three kinds of sand. The results demonstrated that the proposed model can predict not only liquefaction-induced large deformation but also the liquefaction resistance of sand with different relative densities.