87 Influence of Drawdown of Reservoir Water Level on Wanzhou Middle School Landslide Stability

Wanzhou Middle School landslide is a kind of highly representative landslides in the Three Gorges Reservoir area. The landslide is mainly composed of gravel-silty clay, with the underlying layer of pebble sand. It is of great significance to study on the relationship between its stability and the reservoir water level. The numerical simulation of the seepage field is carried out with Geoslope-general finite-element analysis software during drawdown of reservoir water level. The results show that the more the matric suction is, the more advantageous landslide stability is. Moreover, there is strong permeable layer in the landslide Therefore, the landslide groundwater discharge soon, and the water level of the toe and top of the landslide is almost simultaneous dropped so that hydraulic gradient and seepage force are reduced. This will be conducive to the landslide stability. As the reservoir water level dropped, the landslide stability coefficient is depressed at first, and then elevated. The faster the speed of the reservoir water level is reduced, the lower the landslide stability coefficient is.