Kinetic Friction Coefficient and Mass Movement Process of Large Rock Avalanches Triggered by the Wenchuan Earthquake

Kinetic friction coefficient and mass movement process of large rock avalanches are very important to understand the dynamic mechanical characteristics during the sliding process. This paper presents a simple slab model based on energy conservation to determining the kinetic friction coefficient and sliding velocity during the mass movement process. The rock avalanche is assumed as a rigid, non-deformable object moving down slope and subject to the sole Coulomb friction for the presented slab model, and the kinetic friction coefficient is assumed as a certain value during the mass movement process. Five large rock avalanches triggered by the Wenchuan earthquake are selected as the case study examples, and simplified to two stages for these rock avalanches: acceleration stage and accumulation stage, the kinetic friction coefficient and sliding velocity are back analysed by the presented simple slab model. Computed results show that, the kinetic friction coefficient for Donghekou, Woqian, Wenjiagou, Niumiangou and Xiejiadianzi rock avalanches are 0.235, 0.229, 0,306, 0,243 and 0.279, respectively; and the maximum sliding velocity are about 63 m/s, 59 m/s, 64 m/s, 67 m/s and 60 m/s, respectively.