Research on the Deformation Mechanism and Influencing Factors of the High-level Landslide behind the Dam of Jinsha Hydropower Station

The high-level slope on the right bank of the Jinsha Hydropower Station in the Jinsha River Basin has undergone deformation many times in recent years, threatening the safety of the hydropower station below. To study the deformation history and causes of the mountain ridge landslide and ensure the safe operation of the hydropower station, this study employed on-site reconnaissance, unmanned aerial vehicle photography, visual optical remote sensing satellite interpretation, and time-series analysis based on 78 ascending track data of Sentinel-1A to conduct an in-depth study of the time-series curves and deformation and failure history of the mountain ridge landslide before and after treatment. The on-site investigation revealed that the main inducing factors of the 2018 landslide were the roof collapse of the underlying goaf and rainfall infiltration. Comprehensive analysis suggests that the tensile stress area caused by the roof caving of the goaf expanded from the slope surface to the top of the slope, leading to tensile cracking and settlement at the rear edge. Under the action of its own gravity, the rock and soil mass tended to move downward and towards the free face. The lower cracks and the rear edge tensile cracks gradually expanded and intersected with each other, forming the sliding surface. The failure mode of the mountain ridge landslide was "collapse - tensile cracking". New cracks were discovered at the front edge of the site in 2024. The InSAR interpretation results indicate that the slope still is affected by the goaf after treatment, showing creep characteristics, and rainfall promotes this process. Through on-site investigation and InSAR time-series analysis, this study reveals the deformation history and influence mechanism of the high-level goaf landslide, providing a certain reference for disaster prevention and reduction.