ABSTRACT
Toppling deformation mainly develops in the slopes of platy rock mass formed by steepdip-angle cracks and fissures, and the angle between structure plane strike and slope surface one is less than 30 degrees. Toppling failure is one of deformation and failure types of bedded rock mass with high dip angle. It usually develops near the ground surface. Xiaowan Hydropower Station is located in the southwestern part of Yunnan Province, the position between Fengqing County and Nanjian County. It lies at the south of famous Sanjiang Structure Belt in southwest region with complex geological structure. Formation of the large-size toppling deformation failure at last has two basic conditions. One is the slope structure, i.e., stratoid structure and the structure growth with gentle dip angle, the other is the favorable landform condition in the failure region, i.e., gently platform developed at the after-edge of the toppling deformable rock mass.
