The Impact Analysis Of Stability On The Condition Of Rainfall And Drawdown Of Shaiyanba Landslide Of The Three Gorges Reservior

After the Three Gorges Reservoir built,the water in front of the dam 145m ~ 175m ~145m between fluctuation range, 30 for reservoir. Landslide under the action of water environmental factors such as storm will suffer long-term going under water and periodically by water erosion,which generate a penetration,will lose buoyancy's weight,soak softening and the effect and influence of fluctuating load produced by dynamic variation of high and low water level, which will reduce the reservoir bank physicomechanical shear strength, will cause the old landslide and new sliding landslide, this will inevitably affect people's life in the Three Gorges Reservoir area and the normal operation of the Three Gorges waterway transportation. So it is a new important subject of Three Gorges Reservoir operation be faced with which influence on the landslide stability of seepage effects producted by drawdown and rainfall. Landslide seepage and stability evaluation is a complexed and a major theory of engineering application subjects.This article selects YunYangXian chongqing Shaiyanba landslide for research object,in order to analyze the condition of rainfall and drawdown on the question of slopes' stability, on the basis of the saturated-unsaturated seepage theory, the extending method of traditional limit equilibrium method, the thesis have been studied in details about the stability analysis, condition forecast of the landslide and obtain the significative conclusion of Shaiyanba landslide in the condition of the rainfall and drawdown..(1) The geologic background of Shaiyanba is analyzed,such as physical geography,topography and geomorphology, formation lithology, meteorology, hydrogeology and so on. The engineering geological environment of Shaiyanba landslide has been illustrated.(2) Illustrating the essential characteristics, the deformation and failure characteristics and the influence factors, from the internal and external factors affecting the landslide research the damage mechanism of landslide.(3) Explaining the fundamental concept and the definite condition of the unsaturated steady-unsteady seepage. On the base of basic seepage physics equation, regarding pressure hydraulic head as a basic unknown quantity to deduce saturated-unsaturated seepage differential equation, the FEM format of differential equation is deduced based on Galexkin method of weighted residual. Using seepage software given drawdown and rainfall condition on the stability calculation, get the change of phreatic surface and contour graph of total head , pore water pressure in different operations and analysis evaluation, explore the effect of the seepage field by drawdown speed, rainfall intensity, rainfall duration, gradient and so on.(4) From the analysis the mechanism of drawdown and rainfall, which will become the important factors at the stability analysis of Shaiyanba landslide. The paper will put the pore water pressure from seepage field into the stability calculation which based on the unsaturated soil shear strength theory, Fredlund adopts the limit equilibrium method for stability calculation, acquire the evolution of stability coefficient in different operations under the influence of different drawdown speed and rainfall factors. Approach the variation of relevant parameters bear on the slope stability coefficient, then appraise the influence of slope stability coefficient,which is the reliable theory basis for management action presenting.