Post-failure simulations of a large slope failure using 3DEC: The Hsien-du-shan slope

The goal of this paper is to evaluate the post-failure behavior of the Hsien-du-shan rock avalanche, which was triggered by Typhoon Morakot in 2009, using a three-dimensional (3D) discrete element program, namely, 3DEC. The 3D slope topography and local joint sets are explicitly considered in the calculations, and the joint sets cut the sliding rock mass into blocks with arbitrary shapes. The modeled blocks exhibit the elastic behavior of the local rocks. The analysis successfully simulates the wedge failure at the initiation of the landslide. Additionally, the 3DEC results clarify the local rock sliding phenomena at the boundaries of the source area. The simulated depositional area correlates well with the actual area affected by the Hsien-du-shan rock avalanche. In addition, the erosion of a ridge by the sliding rock near the southwestern margin of the area at an elevation of 590 m has a significant influence on the shape and size of the impacted area. The interlocking effect between blocks is also considered.