A double-phase double-layer nonlocal general particle dynamics for modeling submarine landslides

The existing nonlocal methods rely on a single-layer theory, which limits the capability to capture the variation of free surface and to simulate dynamic coupling problems between fluid and soil in submarine landslides. To overcome the above limitations, a double-phase double-layer nonlocal general particle dynamics (NGPD) method is proposed in this paper. Within the developed framework, the entire problem domain is divided into two computational layers that are allowed to overlap, the fluid layer and the soil layer. Each phase satisfies its own laws of motion within its respective computational layer. The numerical stability of the novel NGPD method is enhanced by several key stabilization techniques, such as artificial terms and efficient particle shifting technique (PST). The boundary conditions of the fluid phase and soil skeleton in the proposed method are introduced in detail. Among them, a novel stress boundary for soils is proposed to avoid the particle penetration phenomenon. The Graphics Processing Unit (GPU) acceleration based on the Taichi kernel is leveraged in this work to achieve a parallel solution. To validate the performance of the proposed method in simulating submarine landslide problems, four benchmark examples, including a classical underwater soil column problem with analytical solution and three experimental submerged landslide examples, are studied by the proposed method. The numerical results demonstrate that the proposed method possesses the excellent ability to address water-soil interaction in hydromechanical geotechnical problems. Finally, the proposed method is further applied to model a practical submarine landslide and a submarine retrogressive landslide induced by earthquake.