Three-Dimensional SPH Simulation of the Dynamic Evolution and Deposition of the 2025 Junlian Rock Avalanche

On 8 February 2025, a high-elevation landslide occurred in Jinping Village, Junlian County, Sichuan Province, China. The landslide travelled a long distance through a complex valley and underwent two major changes in direction. A three-dimensional smoothed particle hydrodynamics (SPH) model was developed in ABAQUS/Explicit using the actual terrain. A strain-softening Drucker–Prager model was adopted to describe the strength degradation of the sliding mass, and the simulation was validated against a post-event unmanned aerial vehicle orthophoto, a digital elevation model, and the mapped deposit boundary. The landslide evolved through four stages: initial acceleration, high-speed transport, topography-controlled deflection, spreading, and deposition. The local maximum velocity was approximately 40 m/s, and movement had largely ceased between 45 and 60 s. The simulated deposit thickness ranged from 0 to 9 m, with a thicker main depositional zone and thinner material along the transport corridor and margins. This pattern was consistent with the overall depositional configuration inferred from the measured elevation difference. The model reproduced the two major deflections, runout extent, and deposit geometry, and the simulated boundary and thickness distribution were generally consistent with the observations. These results demonstrate that SPH can effectively simulate the movement and deposition of high-elevation landslides over complex terrain.