Stability analysis and treatment of a reservoir landslide under impounding conditions: a case study

The Muchanghe landslide is located on the left bank of the Muchang River in Dongping reservoir, Hubei Province, China. During reservoir impoundment, cracking and dislocation deformations occurred at the front and middle parts of the Muchanghe landslide. Once the landslide was triggered, the river could be blocked, which would lead to a serious threat to upstream flood control safety. In this study, the engineering geological properties and deformation characteristics of the Muchanghe landslide during impoundment were analyzed. A 3-D limit equilibrium method was proposed for the stability analysis of this asymmetric landslide. Based on the proposed 3-D method, a visualization program (JSlope3D) was developed and applied to evaluate the stability of the Muchanghe landslide. The results indicated that the stability of the landslide gradually decreases with the rise of impounding water level in the Dongping reservoir. When the impounding water level reaches an elevation of 490 m (normal pool level), the calculated factor of safety predicted that the landslide would be in an unstable state. To prevent the generation of a landslide failure, a reinforcement scheme involving the cutting back of the slope and backfill was proposed to improve the stability of the landslide. Using the proposed 3-D method, the Muchanghe landslide, after stabilization, was stable at different impoundment water levels and can satisfy the requirements of the design specification.