Analysis of deformation and failure mechanism of Shuping landslide in Three Gorges reservoir area

Continuous deformation happened in Shuping landslide, since the impoundment of the Three Gorges reservoir from 2003. It is necessary to study the deformation and failure mechanism of Shuping landslide, in order to evaluate and predict the stability of landslide. The field geological survey and exploration are used to determine the form and property. The deformation characteristics of the landslide are analyzed in detail to make full use of monitoring data. The deformation mechanism and influence factors of landslide are studied based on investigation and monitoring; and the stability of landslide is calculated and predicted. Survey and analysis results show that, the geological factors, included topography, lithology and geological structure, control the deformation. The reservoir water fluctuation and rainfall trigger the deformation of Shuping landslide. Indeed, the relationship between slope groundwater fluctuation and reservoir water fluctuation primarily affected the deformation, especially during the decline process of slope groundwater with the drawdown of reservoir water. Because decline speed of groundwater is much slower than that of reservoir water, it increases the hydraulic gradient and seepage force in the landslide body apparently, and then reduces the slope stability, increases the landslide deformation rate especially when the sharp decline of reservoir water level. In addition, if the long-term or intensive rainfall occurs during the drawdown of reservoir water, more obvious deformation will happen and landslide might be failed. So the engineering control measures should be carried out.