Material point method-based simulation and dynamic characteristic analysis of instability-induced landslide movement: A case study of the Yanguan landslide in the Three Gorges Reservoir area

The dynamic process and influence range of instability-induced landslide movement have important effects on the risk area division and prevention of landslide hazards. To accurately and systematically analyze the changes in the dynamic characteristics of landsides during their instability-induced movement, this study thoroughly investigated and analyzed the instability-induced movement process of the Yanguan landslide in the Three Gorges Reservoir area, Zigui County, Hubei Province. Through laboratory ring shear tests, this study determined the changing pattern of residual strength and the motion parameters of sliding zone soil under different shear rates. Accordingly, using the material point method (MPM), which is suitable for the simulation calculation of large deformations, this study reproduced two movement and accumulation processes of the Yanguan landslide. Furthermore, it analyzed the dynamic changes and staged characteristics (e.g., velocity, energy, and impact force) of the dynamic characteristics in the process of landslide movement. The results show that (1) The simulation results of the Yanguan landslide obtained using the MPM are consistent with the movement distances and deposit morphologies determined through field investigation. (2) Each movement process of the landslide can be divided into four stages: instability initiation, accelerated sliding, decelerated accumulation, and steady stop. (3) During the first and second sliding events, the peak velocities reached 1.9 m/s at 10 s and 3.2 m/s at 31 s, respectively, the total kinetic energy was 1.57×10⁷ J and 1.60×10⁸ J, respectively, and the peak impact forces were 7.82×10³ kN and 3.87×10⁴ kN, respectively. (4) The average velocity, total kinetic energy, and maximum impact force of the landslide increased first and then decreased with an increase in the sliding distance. The results indicated that the MPM yielded encouraging results in the dynamic analysis of the landslide. Furthermore, the laboratory ring shear tests determined the sliding zone soil’s residual friction coefficient, which controls the landslide movement, providing reliable data for the MPM-based simulation calculation. The dynamic characteristics of the instability-induced landslide movement are of great significance for the scope and degree prediction and risk assessment of landslide hazards.