Formation mechanism, deformation characteristics and stability analysis of Wujiang landslide near Centianhe reservoir dam

• Formation conditions and evolution of Wujiang Landslide process are investigated.
• Deformation characteristics of Wujiang Landslide are described.
• A new stability analysis method is proposed.
• Its stability are analyzed and its dominant sliding direction is identified during impoundment of reservoir.

Wujiang landslide, which is an ancient landslide, has a total volume of approximately 1.327 × 107 m3. Its downstream boundary is approximately 300 and 590 m away from the new dam and axis of the dam, respectively, while the upstream boundary is approximately 1000 m away from the dam. The relative relief of the landslide ranges from 380 to 480 m with moderately steep terrain and well-developed gullies. In this study, we have investigated the geotechnical characteristics of the landslide and analyzed its formation conditions and evolution process. We conclude that the landslide can be classified into the bedrock crack-bedding slip mode and is an ancient landslide where creep deformation still exists although it has undergone repeated sliding evolution. We have further analyzed its deformation characteristics: the landslide is currently in a slow creep deformation state, with the deformation larger at the leading edge and smaller at the trailing edge. Hence, the disintegration of the superficial part or the slip of the shallow-upper part of the landslide is likely to occur. Conversely, the possibility of the whole slope sliding down is relatively low. Finally, based on Morgenstern-Price assumptions, we have developed a rigorous three-dimensional analysis method that can analyze the stability and identify the dominant sliding direction of the landslide during the impoundment of the reservoir.