The Research On The Stability Of The Reservoir Bank In Fengjie Section Of The Three Gorge Reservoir, The Yangtze River

The key problem of "Reservoir Slope Stability" is the interaction between slopes and impounded water. By studying the international extent of reservoir slop, ICOLD think that the development of a conceptual hydrogeological model for a slope and knowledge of groundwater pressures acting within slopes of reservoir bank are essential. The results should be used in stability analysis.After the Three Gorge reservoir, the Yangtze River storing water to 175m梚ts normal water level ,almost the whole Fengjie city would be submerged . It must be moved entirely .Now the job of constructing the new city has been carrying on .The stability of the reservoir bank in Fengjie section will directly influence the process of the city's constructing and the normally operation of the whole Three Gorge hydraulic project.On the basis of the investigation in situ and the analyzing of the datum collecting, this paper studies the dynamic character of the groundwater seepage field and thoroughly demonstrated the change character of the stability of he reservoir bank in Fengjie section during the process of water storing and normal operation of the Three Gorge reservoir. The result provides scientific basis for the city's constructing.By studying the principal types and character of the rocks and soils in Fengjie section, the structure of reservoir bank and its combination types and the developing and distributing status of the reservoir bank's deformation and breakage. Reservoir bank in Fengjie section, which is 10.352 kilometres long from Lijia big valley to Laolongdong valley, is systemic classified as 12 engineering and geology subsections. The Reservoir bank being composed of rock slope is 2142 kilometres, 20.7 percent of the whole Reservoir bank. The Reservoir bank being composed of rock slope is 8210 kilometres, 79.3 percent of the whole reservoir bank.By analyzing and studying the hydrogeology condition of The reservoir bank, typical zone is selected to build the realistic hydrogeology and mathematic model. The dynamic character of the groundwater seepage field of slopes in Fengjie section during the present time, the initial process of storing water and operation of the reservoir, the late process of storing water and operation of the reservoir is imitated with 3D-Modflow. During the process of modeling, three conditions of reservoir water level's ascending, slowly descending and sharply descending are considered.Then the stability of typical slopes in different conditions such as servoir water level's ascending, slowly descending and sharply descending are evaluated and forecasted by means of the limiting balance method and the numerical simulating method(FLAC). The result show thatLaofangzi slope has high possibility to destroy during the process of storing water of the reservoir and will destroy when reservoir water level sharply descend . Sichouchang slope is also probably to destroy though its stability is better than that of Laofangzi slope. Other slopes of the whole reservoir bank that will not wholly destroy will partly destroyed with the means of peeling off by reservoir water.On basis of the concrete character of the whole reservoir bank, the reconstruction of reservoir bank is valuated and forecasted by means of analogy method, which means to acquire the ultimately stable slope angel of zone being affected by reservoir water after reservoir storing water by analogy to the slopes' configuration parameters of the Yangtze River before the reservoir storing water. The result show the reservoir bank being strongly reconstruction is 4.05 kilometres long,39.1 percent of the whole reservoir bank.