The Slope Stability Analysis And Bank Rebuilding Forecast About Jiatanchang Riverside In The Three Gorges Reservoir Area

With the development of human social economy, the development and utilizationof Water Resources and Hydropower have entered an unprecedented stage. Waterconservancy and hydropower projects have great benefit for future generations, butalso have damage to geological environment of the reservoir area. After reservoirimpoundment, there will be a significant change in geological conditions of coastalareas, causing soil erosion and deposition, or dam failure, which will cause significanteconomic losses and casualties.In this paper, Jiatanchangzhen reservoir has been taken for example, with fullcollection and using of the existing data, the deformation and failure mode has beeninitially determined and reservoir bank has been segmented. Then Limit EquilibriumTheory was selected to analyze and evaluate the slope stability. Under the premise ofengineering geology and stability analysis, Kachugin Method was applied to forecastbank collapse; combining with urban planning and ecological protection, thecorresponding protective proposal has been put forward. The obtained results are asfollows:1. According to the basic principles of bank section, the reservoir bank wasdivided into760segments and761segments.760segments: The bank spreads along YuDong Road as long as200meters. Theelevation of trailing edge is200meters and the leading edge is188meters, with12meters relative height. The slope is steep outside YuDong Road and the overall slopegradient is30o～35o.761segments: The bank spreads along JiangNan School Road as long as300meters. The elevation of trailing edge is194meters and the leading edge is188meters, with6meters relative height. The slope is steep outside JiangNan SchoolRoad and the overall slope gradient is25o～35o.2. The main deformation characteristics of the reservoir bank is small-scale collapse at leading edge and steep slope areas, leading to the housing cracking attrailing edge and the top of the hill, tensile fractures on road surface and saber-shapedtrees on bank slope.3. Typical profiles were selected respectively on both760and761segments, andthen the geological and mechanical model were established. Limit equilibrium theory(Sarma、Bishop、Janbu、Unbalanced Thrust Method) were used to calculate thestability of bank slope in six different conditions. The results showed that the stabilitycoefficient along the contact interfaces between fill and Quaternary silty clay,Quaternary soil and gravel layer, was large, therefore damage would not happen; thestability coefficient of internal Quaternary arc-shaped sliding on760section was large,so the bank slope was stable; the stability coefficient of internal Quaternaryarc-shaped sliding in last three conditions on761section was small, so the bank slopewas instable.4. Under the premise of engineering geology and stability analysis, KachuginMethod was applied to forecast bank collapse. The forecasting widths of760and761sections are both larger than20m, so the intensity of bank reformation is strong.5. According to the stability of reservoir bank, bank collapse predictions andcombat–effectiveness analysis, prevention and control measures, such as ecologicalmanagement and project governance can be taken. The reservoir bank is the type oferosion, the affecting objects of760section are three residents, comparing toengineering treatment measures, relocation of avoidance is suggested, and theaffecting objects of761section is JiangNan school road, the slope protectionmeasures are suggested.