Abstract:A simulation was carried out on initial collapsing-sliding and a subsequent running out process of Wangjiayan Landslide in Beichuan County during the Wenchuan Earthquake triggered by single and combined action with time difference, regionality and spatial heterogeneity of primary and secondary seismic waves based on discrete element method by taking into the consideration the fact that vertical ground motion was still evident in post-earthquake field geological investigation, and formation mechanism and key controlling factors of slope collapsing and sliding under seismic load were determined,which was different with the traditional dynamic response analysis based on a consideration of horizontal seismic load. The result shows that initial collapsing and sliding of the slope are triggered by combined action of vertical and horizontal tension, which plays a dominant role,of primary seismic wave, whereas a subsequent collision and debris flow of slope mass fractured are triggered by combined action of primary and secondary seismic wave. On the other hand, single action of primary seismic wave is the key controlling factor inducing the slope initial collapsing and sliding, and the topography near the slope is the key controlling factor leading to collision and debris flow of the slope mass fractured in later process.
