Stability prediction of the toppling rock slope on the Heihe reservoir bank using discontinuous deformation analysis

The Heihe Water Diversion Project in Zhouzhi County, Shaanxi Province is a “lifeline” engineering project that supplies water as well as electric power to Xi’an City, China. This canyon-type reservoir is located at the mouth of the Heihe River on the northern flank of the Qinling Mountain. Slope stability of the reservoir bank is one of the critical geological engineering problems, among which the toppling rock slope of Shuimengou is a major threat to the dam and downstream residents. The toppling rock mass was formed by downcutting of the river, and the hard thin-layer metamorphic schist gradually bent under the action of gravity. Monitoring data in recent decade showed that the process of toppling continued slowly. Under the erosion of the reservoir water the stability of the toppling slope may deteriorate in the coming time. Hence, it is essential to predict the stability of the slope and to give a proposal for mitigation. For this purpose, this paper simulates and analyzes the deforming process of the toppling slope in geological history using the discontinuous deformation analysis (DDA) method. Furthermore, in consideration of the reservoir erosion at the foot of the slope the future deformation-failure of the slope is also simulated. Based on the result, a reasonable counter measure is proposed for stabilizing the slope.