Unified modeling for sand under generalized stress paths.

摘要

Experimental observations have shown that sand behavior depends not only on the initial densities and confining stresses, but also on inherent anisotropy and stress paths. The unified sand model developed at Columbia University which was based on the generalized plasticity theory simulated well the sand response under different initial densities and confining stresses with one set of material parameters. Nevertheless, the development and validation of this model was focused on triaxial stress conditions.;Furthermore, as part of practical applications, the proposed model was employed to analyze the four full-scale shake table tests conducted on the modular block geosynthetic-reinforced soil retaining walls under earthquake loadings. The foundation and backfill soil were simulated by the proposed model, while the geosynthetic behavior was simulated by a one-dimensional bounding surface plasticity model. The surface-based contact interaction was used to simulate the interactions between different materials in the numerical analyses. The results of simulation compared favorably well with the experimental results and previous numerical simulations.;In this study, a sand model was proposed based on the generalized stress version of the unified sand model and the extended critical state framework of Li and Dafalias (2002) in capturing inherent anisotropic behavior of sand under different initial densities, confining stresses, and stress paths. Incorporated into ABAQUS, the proposed model was validated against various types of sand under triaxial compression and extension tests, true triaxial tests and simple torsional shear tests. The simulation of cyclic triaxial tests and cyclic true triaxial tests were also conducted. The proposed model was able to capture the sand behavior under complicated stress paths and loading conditions.