Numerical modelling of the 2008 Wenchuan earthquake-triggered Daguangbao landslide using a velocity and displacement dependent friction law

Dynamic friction degradation of the sliding surface in large earthquake-triggered landslides is widely assumed, especially for high-speed and long run-out landslides. But there are few numerical simulation methods that consider the friction degradation of the sliding surface during landslide movement. In this paper, based on the results of the high-velocity rotary-shear experiments (Tsao, 2014) on the dolomite and fault gouge on the sliding surface of the Daguangbao landslide induced by the 2008 Wenchuan earthquake, a corresponding velocity-displacement dependent friction law was assumed. The law quantitatively describes the slip-weakening effect on frictional resistance on the sliding surface, and was incorporated into a discontinuous deformation analysis (DDA) to assist in further understanding the movement behaviors of the landslide. Relative to the original DDA, the simulated results from this enriched DDA suggest that the Daguangbao landslide exhibited a longer run-out and faster travel speed during the earthquake. Moreover, the simulated run-out and deposit pattern from the enriched DDA are in good agreement with the results of actual surveys. In addition, the modeled kinetic process of the Daguangbao landslide considering dynamic friction degradation of the sliding surface, is classified into four stages: further deepening of the pre-existing tensile crown cracks, shear failure along the sliding surfaces, rapid friction degradation of sliding surfaces and high-speed sliding, with some reduction in velocity along the opposite slope surface.