Numerical Analysis of Sand Behavior based on Semi-Micro Bounding Surface Model

This contribution presents a numerical model for estimating the load in a sand box containing a buried steel pipe under cyclic loading. The reliability test is based on two physically and statistically independent sets of experiments: the first set concerns elastoplastic material modeling, and the second set concerns structural model verification. Accordingly, an induced anisotropic plasticity model predicting the dynamic behaviour of sand is presented. The model incorporates the critical/steady-state concept, which postulates the existence of a state in which sand continuously deforms at a constant effective stress, depending on two main parameters: the initial bulk parameters (i.e., void ratio or relative density) and the stress level (i.e., mean stress). The local instability of saturated sand in post-liquefaction conditions is highly dependent on residual inherent/induced anisotropy, bedding-plane effects, and stress/strain path. The constitutive equations of the model are derived within the context of non-linear elastic behaviour of the entire medium and plastic sliding at predefined multilaminar interfaces. The proposed multi-laminate-based model can predict soil behaviour based on plastic sliding mechanisms, the elastic behaviour of particles, and the ability to account for microfabric effects, including natural and induced anisotropy in plasticity