Analysis of the deformation mechanism and reinforcement treatment for the right abutment high slope of Yebatan Hydropower Station

Yebatan Hydropower Station is located in the complex geological zone at the edge of the Tibetan Plateau in the upper reaches of the Jinsha River. The slope in the junction area has large excavation height, strong unloading and complex geological conditions. After the excavation of the right abutment slope, more than 300 cracks appeared in the slope surface and adits along f29, fr18, f85 and other faults. The deformation and cracking mechanism of the slope, the current stability of the slope after cracking, and whether to take emergency reinforcement are the key technical problems that need to be answered in the construction stage of Yebatan Hydropower Station. In this paper, the boundary conditions and failure modes of the right abutment slope are investigated by a comprehensive method integrating engineering geological condition analysis, monitoring data analysis, three-dimensional limit equilibrium analysis and numerical simulation. Under the influence of the combined factors of slope excavation and unloading, lagging support and softening of construction water seepage, the stability of the wedge-shaped blocks formed by the faults f29 and f85 decreases, resulting in the creeping deformation directed to the riverbed. The upstream and downstream boundaries controlling the overall stability of the slope are the faults f85 and f29 respectively, and the failure mode is wedge sliding. According to the normal and shear stress distribution on the sliding surfaces of the wedge block, the emergency reinforcement measures of anti-shear tunnels arranged along the faults of f29 and f85 are proposed, supplemented by engineering measures of anchor cables and drainage. The stability analysis results indicate that the emergency reinforcement measures can significantly increase the stability of the block, and the reinforced slope can meet the stability requirements. The research can be used as reference for the mechanism analysis and emergency reinforcement treatment of high rock slopes with similar deformation and cracking failure.