Distinct Element Modelling of a Landslide Triggered by the 5.12 Wenchuan Earthquake: A Case Study

Abstract

The Donghekou landslide, which was triggered by the 2008 Wenchuan earthquake, was estimated to have a volume of 24 million cubic meters and resulted in numerous properties and lives lost. The landslide is considered a typical rapid long run-out earthquake-induced event, but the kinematic processes are not well understood. The main objectives of this study were to numerically model the landslide progression and to reproduce the post-failure configuration. We first built a physical model of the slope based on the topography and geology of the source area from field investigations. The corrected baseline and filtered actual ground motions were then used as the volume force acting on the base block, and the kinematic process and mechanics of the throwing phenomenon were modelled using a 2-D discrete element code. We used the non-linear Barton–Bandis criterion to accurately simulate the behaviour of joints. The size effect of the enormous landslide was also considered. The results of the simulations agreed well with those obtained from post-earthquake field investigations. A sensitivity analysis of several related parameters that may control the dynamic movements of the Donghekou landslide was discussed in detail. The results show that: the seismic force and the residual friction angle were main factors that affect the run-out of landslides.