The mechanism of high-speed motion and damming of the Tangjiashan landslide

Understanding the mechanisms of landslide failure and resulting damming processes is crucial for constraining the hazard chain associated with landslide damming events. On May 12, 2008, the Wenchuan earthquake caused a large number of secondary hazardous events such as landslides and collapses, most of which occurred in high mountain gorges. In these areas, the sliding distance of landsides is often very short, and the landslides are often characterized by high speed, short distance, and damming. Using the Tangjiashan landslide damming events induced by the Wenchuan Earthquake as a model, this paper reconstructs the three dimensional failure and associated damming caused by the landslide based on a detailed geological investigation of the landslide area and using the dynamic finite element technique. The study proposes a four-stage model for the failure and damming process of the Tangjiashan landslide: earthquake induction and progressive destruction of the slide body, destruction and high-speed sliding of the slide body, slide body impact, disintegration, and river blockage for the formation of a damming body, and vibration compression. The average speed of the Tangjiashan landslide reached a maximum value of 22 m/s about 30 s after the earthquake, and the landslide reached stability about 60 s later.