Investigation of the mass movement and thermal pressurization effect of rapid and long-runout landslides in Shuicheng, Guizhou, China

Abstract

The speed, distance and energy evolution of rapid and long-runout landslides are crucial indicators for evaluating the characteristics of these catastrophic landslides. The Shuicheng rapid and long-runout landslide was chosen as an example for further study, and the evolutionary process of landslide motion was simulated by PFC. The kinematic characteristics and dynamic mechanism were experimentally studied with the above three indicators, and the results indicated that the landslide lasted approximately 60 s and could be divided into four stages: uniform deformation, erosion-disintegration, block-spilt and convergence-accumulation. The speed of the landslide peaked at 36.1 m/s at 28 s. Controlled by the terrain, particles collided violently, and there was strong momentum transfer, which greatly promoted the long-runout movement of the landslide, with a maximum movement distance of 1303 m. During movement, gravitational potential energy was mainly converted into dissipated energy of friction and collision, accounting for 51.0 % and 39.6 %, respectively, of the total gravitational potential energy released during the landslide. After the landslide initiated, the apparent frictional coefficient reached a peak of 0.49 in 6 s. Then, the apparent frictional coefficient gradually decreased and stabilized at approximately 0.32. The factor leading to the decrease in the apparent frictional coefficient was the rapid increase in the dissipated energy of friction. In addition, it was found through quantitative calculation that the dissipated energy of friction generated in the propagation can cause the basal facies to rise by 65.08 °C. The results from the numerical simulations are in agreement with the findings from the field investigation, affirming the thermal pressurization impact associated with rapid and long-runout landslides. These simulations yield insights that are scientific merit for understanding the kinematics and dynamics underlying these types of landslides.