Failure evolution of anti-dip rock slope in the Three Gorges reservoir area

Many landslide and collapse events are found since the filling of the Three Gorges Reservoir. It is studied that the instability of the side slope in reservoir is strictly related with the reservoir water fluctuation. In this paper, taking the Gongjiafang landslide as an example, the discrete element model was established based on the detailed engineering geological survey of the landslide. The water-rock interaction within the fading zone caused by reservoir water fluctuations was considered to explore the erosion and failure process, and the seepage mechanism of rock mass in the anti-dip slope. The numerical simulation shows that the evolution process of Gongjiafang landslide can be divided into three stages: (1) erosion and softening of slope foot. (2) Failure of slope foot rock. (3) Failure of middle and upper rock. The thick rock beam in the middle of slope is the key factor of the entire slope failure. It finally bends and breaks due to the lack of support at the lower part and the squeezing of upper rock mass, which is the sign of the entire slope instability. Although the occurrence of rock layers in different parts of the slope is similar, the failure modes are not identical. Bending and toppling deformation are found in the thin layered rock mass at the lower part of the slope, while the bending damage occurs at the middle rock beam, and the composite mode of slip-dumping failure is applicable for the upper rock mass. © 2020, Science Press. All right reserved.