Study on Formation Mechanism of Liujiawan Landslide Triggered by Wenchuan Earthquake

Since May 12^th, 2008, it has been already determined that tens of thousands of landslides were triggered by Wenchuan earthquake. However, full understanding of the mechanism of seismic landslides is still unclear due to the complex geological condition and dynamic action of seismic wave. This paper presents the Liujiawan landslide accumulation characteristic and intends to analyze the formation mechanism under the Wenchuan earthquake. Based on field investigation, a unique geological condition of Liujiawan landslide appears two stage platform accumulations with different lithology, which have an obvious landslide boundary in lithological interface and unloading weathering zone. These characteristics are hardly found in other types of landslide. In the meanwhile, a numerical model displays tension stress concentration on the lithology boundary surface. From the results, it can be concluded that the seismic waves propagate through the different physical properties of interface and structure plane, which mutated strong dynamic stress and induced slope failure. The dynamic stress mutations should be considered as the triggering factor of Liujiawan slope failure.