An improved CFD-DEM coupling method for simulating the steady seepage-induced behaviors of soil-rock mixture slopes

Abstract

Modeling the seepage-induced progressive failure of soil-rock mixture (SRM) slopes is challenging because of the large deformation and the complexity of stress-seepage coupling. To address these challenges, this study presents a numerical approach for modeling the seepage-induced progressive failure of SRM slopes, where rock blocks within slopes and the effect of cracks on seepage behavior during slope failure are explicitly considered and modeled. Within the proposed method, the traditional unresolved computational fluid dynamics-discrete element method (CFD-DEM) coupling method is first improved by introducing the unstructured mesh and hydraulic boundary condition to model the seepage-induced progressive failure of SRM slopes. The seepage behavior within SRM slopes is modeled with a CFD solver based on finite volume methods, while the particle motion under these interaction forces is simulated with a DEM solver. Note that fluid-particle interaction forces are calculated with empirical equations in the improved CFD-DEM coupling method. CFD-DEM coupling is achieved by exchanging data between the two solvers at each timestep. The proposed numerical method’s effectiveness is illustrated through two seepage problems (within an SRM sample and an SRM slope) and three model tests with different rock contents (in terms of 10%, 20%, and 30%).