Micro-mechanism of contact erosion between soil layers under cyclic loading based on CFD-DEM coupling

Abstract:

To investigate the seepage erosion characteristics commonly found between soil layers under cyclic loading and to reveal the micromechanical mechanisms of contact erosion under water-flow coupling, a three-dimensional computational model for soil contact erosion was developed, based on the coupling of computational fluid dynamics (CFD) and discrete element method (DEM), considering the influence of cyclic loading amplitude. Firstly, the movement patterns and spatial distribution characteristics of the particles were analyzed within different cyclic loading periods. Secondly, the macroscopic deformation characteristics resulting from particle erosion were explored. At the same time, two localized deformation regions were selected to study two typical particle migration modes. Finally, the evolution mechanism of particle contact mechanics during the erosion process was discussed, combined with force chain analysis. The results show that during a single cycle of loading, the compression of coarse particles caused by loading and the stress relaxation induced by unloading are the primary factors responsible for the migration of fine particles. Cyclic loading induces intense particle migration at the soil layer interface, resulting in significant axial deformation of the sample. Simultaneously, the seepage field generates an upward hydraulic gradient that promotes the pump-driven migration of fine particles. A threshold value for the loading amplitude exists, and the soil rapidly compacts when the cyclic loading amplitude exceeds this threshold, leading to a reduction in erosion-induced deformation.