Numerical simulation analysis of resurrection and surge of paleolandslide based on FDE-SPH method

Reservoir-triggered landslides present critical challenges to the sustainable development of hydropower infrastructure in mountainous regions. This study focuses on a representative paleolandslide in the Gushui Hydropower Station reservoir, Upper Lancang River. An advanced fluid-solid coupling model integrating the finite discrete element (FDE) and smoothed particle hydrodynamics (SPH) methods was developed: the FDE method was designed to insert zero-thickness cohesive interface elements between finite elements, enabling simulation of the landslide mass’s deformation, progressive fragmentation, and movement. The SPH method, by contrast, was capable of flexibly handling the evolution of the free surface of water and wave propagation, and accurately simulating the dynamic coupling interaction between the landslide mass and water after the landslide mass enters the water. Simulation results reveal that the landslide fragmentation process consists of three stages: initial disintegration, movement fragmentation, and post-fragmentation. The destabilized landslide mass reaches a peak velocity of 80 m/s, generating impulse waves with a maximum surge velocity of 34 m/s and a maximum run-up of 50 m on the opposing shoreline. Comparative simulations using computational fluid dynamics methods demonstrate that the FDE-SPH framework more accurately captures real-world landslide motion by resolving discrete particle interactions and energy dissipation through fragmentation and collisions.