Failure analysis of soil-rock mixture slopes using coupled MPM-DEM method

A 3-D concurrent MPM-DEM (material point method - discrete element method) scheme is proposed and developed in this paper to simulate soil-rock mixture slopes. The MPM and DEM are treated as two individual parts linked by the coupled contact force. Compared with MPM, the proposed MPM-DEM scheme provides a more realistic contact detection. Compared with DEM, the scheme can model such cases more efficiently and conveniently. Based on the characteristics of the soil-rock mixture, a CPU-GPU concurrent solving scheme is introduced, which can improve the efficiency and make full use of the computational resources of both GPU and CPU. The accuracy of the MPM-DEM scheme is validated by three benchmark examples, i.e., a block sliding on an inclined plane, granular flow impacting blocks, and collapse of hybrid granular columns. The failure mode and sliding distance of soil-rock mixture slopes are analyzed using the proposed MPM-DEM scheme and compared to a pure MPM. Influencing factors such as soil-rock friction and cohesion, rock content, and rock size are studied. The results indicate that this scheme can well capture the soil-rock interface and deal with complex interactions between soil and rock.