The Impact Of Reservoir Water Fluctuation On Sidaoqiao Landslide Stability In Three Gorges Reservoir Area

Since the Three Gorges Reservoir was put into operation, the reservoir water level was fluctuated between 145 m and 175 m frequently, which formed a slide zone of about 30 meters. The balance of the original geological environment was influenced by the water level fluctuation greatly, combined with the complex geological environment and rainfall, geological disasters such as landslide is easily happened in this area. The landslide under the action of the reservoir regulation caused great damage and threat to the reservoir operation, public facilities and people’s life and property, the deformation mechanism and stability trend draw a wide attention of scholars both at home and abroad, the study on the groundwater dynamic response, reservoir bank landslide formation mechanism, landslide stability prediction has important scientific value and practical significance on the prevention and control of landslide.This paper makes the Sidaoqiao landslide in Wushan mountain area Three Gorges Reservoir District to be the research object, analyzes the geological environment of Sidaoqiao area such as Meteorological, landform, stratum lithology, geological structure and hydrogeological condition, relaying on the groundwater dynamic and deep displacement data collected by the real time monitoring system, combined with landslide geological environment background, makes the study of the landslide body groundwater dynamic change process during the process of rainfall and reservoir water fluctuation. Based on the survey data, test data and the real-time monitoring data, builds model by use of the SEEP/W and SLOPE/W of Geoscience software, simulate and analyze the impact of reservoir water level fluctuation rates on the landslide stability of typical gravel soil accumulation.The results show that the impact of reservoir water rising or falling rates on reservoir landslide stability is controlled by a variety of factors, including the hydrostatic pressure, hydrodynamic pressure, uplift force, physical and mechanical properties change of the rock-soil mass(change of c and φ value). The controlling factor is hydrostatic pressure when the water rising or falling rate is a larger value before the stability to be maximum; and after that, with the infiltration or drainage of the reservoir water, the stability trend depends on physical and mechanical properties change of the rock-soil mass and uplift force; and when the water rising or falling rate is a smaller value the impact of reservoir water rising or falling rates on reservoir landslide stability is controlled by comprehensive affecting factors such as the landslide porewater pressure, reservoir water uplift force, physical and mechanical properties change of the rock-soil mass and so on.