Back-analysis by UDEC of the Failure Process of Wangjiayan Co-seismic Landslide during 2008.5.12 Wenchuan Earthquake.

Strong earthquakes such as the 2008 Wenchuan earthquake often induced numerous landslides, which resulted in a large number of casualties and property losses. Under a strong earthquake, a rock slope often produced a dynamic progressive failure. Understanding the process of the dynamic progressive failure of the rock slope is of great significance for the prediction and prevention of the co-seismic landslide. Generally, the numerical method is a feasible and economic alternative to solve this problem. However, previous studies presumed the failure surface and area in the numerical model, which cannot reproduce the dynamic progressive failure of the rock slope. In this paper, we applied the Universal Discrete Element method (UDEC) was adopted to quantitatively characterize the dynamic progressive failure process of the Wangjiayan co-seismic landslide triggered by 2008 Wenchan earthquake. Different from previous studies, there exists no presumed failure surface and area was was presumed in the UDEC model. The initiation, coalescence of the local fractures and the formation of the final failure surface were well simulated in a real-time way. Some key factors influencing the dynamic progressive failure of the rock slope were systematically explored. This study provided a new insight to understand the disaster-pregnant mechanism, evolution, and formation of the co-seismic landslide.