Effect of the acceleration component normal to the sliding surface on earthquake-induced landslide triggering

Abstract

In 2008, the Wenchuan Mw 7.9 earthquake triggered a large number of landslides in the Longmenshan area. Among them, the Donghekou landslide is a gigantic one, which buried four villages and one elementary school. During the Wenchuan earthquake, large accelerations, especially vertical, were produced, which should to be taken into account in the dynamic analysis of slope stability. However, the vertical acceleration, which can largely influence the acceleration component normal to the sliding surface, is often overlooked in dynamic analysis of slope stability. In this work, the initiation of the Donghekou landslide is analyzed by using Newmark’s sliding block model. Comparative analyses of conditions both with and without an acceleration component normal to the sliding surface, which is contributed mainly by the vertical acceleration, are then conducted to investigate its role in triggering the Donghekou landslide. Research results show that the initiating time of the Donghekou landslide would be earlier considering the acceleration component normal to the slide surface than without it due to larger estimated Newmark displacement. This conclusion is then verified by simulated results on the basis of DEM. It means that initiation of landslides can be influenced significantly by seismic acceleration component normal to sliding surface, especially in the area with large vertical acceleration.