Response of a landslide to reservoir impoundment in model tests

Landslides are often induced or activated by reservoir impoundment within the reservoir area. In this paper, a physical model test was conducted and compared with another published test to investigate the deformation characteristics and failure behavior of a colluvial landslide for conditions with and without reservoir impoundment. The laboratory landslide model represented the lower part of a landslide in the Three Gorges Reservoir area. A thrust load was applied to represent the upper part of the landslide. The thrust load, surface deformation, pore water pressure, and soil pressure were recorded during the experiments. The results show that the effect of the reservoir impoundment reduces the time to failure of the landslide and the load causing the failure. As expected, when water submerged the lower part of the landslide, the shearing resistance was reduced. The slip surfaces and failure behavior of the landslide under the two conditions are different. The entire landslide mass slid along the contact between the colluvium and the bedrock under reservoir impoundment. However, without a reservoir, the landslide slides partially along this contact, and multiple slip surfaces through the colluvium.