Zipingpu Hydropower Spillway Slope Run Of Long-term Stability Evaluation

The dam for Zipingpu hydroelectric power station is loacated in the upriver of Minjiang River. The ability of the station to discharge flood is beared mostly on the draining runnels and the spillway which is closed to the right shoulder of dam, and was built along the bar-ridge. During the period of construction, the inside mountain of spillway was excavated largely and deeply, forming a high-cliffy slope called the inside slope of spillway, with the length near 500m, height near 200m, and angle of slope between 30° -60° . The exposed rock in study area is a suite of sandstone and shale, which belong to the Xujiahe group of Trias. The structure of the slope's rock mass is comparative cracked, controlled distinctly by the lithology of the slope, slidding along bedding plane obvioursly. Because of such complex geology environment and construction condition, during the period of impounder, the long-term stability of the inboard slope will be a key problem for the safety of whole station in the period. So it's a very important and essential to study the inboard slope' secular stability of the spillway.In this paper, the author has investigated the geology environment and construction conditions, and has finished the rheology test for the weak rock mass, and has analyzed the characters of slope's lithology, structure, and characters of failure during period of construction. On those base, the author has worked out the key factors which control the stability of the slope, namely groundwater and creeping of weak rock mass. After so on, the mechanism how the groundwater effects the failure of rock mass was studied comparatively deeply, and the author has simulated the character of seepage field and the level of groundwater of the slope in the process of reservoir's water level ascending and dropping with the method of finite element , and has simulated the trend of the slope's deformation since the reservior will have stored water with FLAC^3D. In the end, on the base of above studying, the author brings forward the method for evaluating the long-term stability of slope, and works out the comparative scientific and credible result for the inside slope's stability. As a whole, in this paper, the author has acquired the following outcome.1. Analyzed the rock mass's failure modes and mechanism of the slope during the period of construction.2. Pilot studied the creeping characteristic of weak rock mass and the mechanism that affecting the slope's stability.3. Studied deeply the dynamic characteristic of seepage field and the mechanism that affecting the slope's stability. during the period of product.4. Studied ulteriorly the trend and characteristic of the slope's deformation during the period of product4. Analyzed every section's long-term stability status of the slope.