Numerical simulation analysis of the solid-liquid coupling process in a hybrid landslide: A case study of the Wushanping landslide

Abstract

The solid-liquid coupling process is crucial in transforming debris flow to mudflow to form a hybrid landslide, which extends the disaster-affected area. It is a hot topic and a tricky problem to be solved in disaster prevention and mitigation research. We used the self-developed post-landslide damage numerical simulation platform (LPF3D) to explore the dynamic process of the Wushanping landslide induced by heavy rainfall in Chongqing under hydrodynamic action and revealed the solid-liquid coupling mechanism. The results show that hydrodynamic effects in the landslide movement are mainly manifested as liquefaction and dragging. The incremental effects of the two hydrodynamic actions are apparent, which often transform debris flow into mudflow, causing long-runout disasters. A two-phase coupled computational model based on the SPH method is proposed. It restores the two-phase movement of the Wushanping landslide under heavy rainfall conditions considering the combined effects of the fluid state equation, the solid viscoplastic constitutive equation, and the inter-phase forces. The numerical calculation results show that the maximum velocity of the Wushanping landslide is 34 m/s, the maximum accumulation thickness is 21.5 m, the accumulation area is 0.12 km2, and the farthest movement distance is 1300 m. The simulation results are consistent with the actual landslide's accumulation pattern. In conclusion, in the high remote landslide risk investigation and prediction process, the pore water pressure and solid-liquid phase interaction under heavy rainfall conditions need to be fully considered, and the numerical simulation based on the LPF3D method provides a basis for the quantitative risk assessment of high-elevation and long-runout landslides.

Keywords

• solid-liquid coupling effect
• hybrid landslide
• post-failure movement
• evaluation methods
• numerical simulation