Study on Reactivation and Deformation Process of XierGuazi Ancient-Landslide in Heishui Reservoir of Southwestern China

With the development of hydropower project in southwestern China, water impoundment induced landslides have become the most hazardous geological problems in the valleys incised reservoir. XierGuazi ancient-landslide in Heishui reservoir, with total volume of 1.35 × 107 m3, is a typical case for reactivated landslide. The landslide was an ancient landslide, its frontal part runout during the impoundment, worse still, a town and a tunnel those are adjacent to the landslide, are now at great risk. Based on detailed survey of the landslide, the reactivation behavior of landslide was studied. Through geological analysis, the failure mechanism was examined, and we concluded that the activation of landslide was controlled by water level fluctuation. A numerical simulation was used to simulate the special deformation process of landslide’s activation. We also performed that the reactivated body will keep moving under water level fluctuant condition, but the sliding materials will be disintegrated in part and the movement will be slow.