Deformation history and genesis analysis of high-elevation landslide behind dam of Jinsha Hydropower Station

In recent years, repeated deformations have occurred on the high-elevation slope on the right bank of the Jinsha Hydropower Station in the Jinsha River, threatening the safety of the downstream dam. Focusing on the Shanliangzi Landslide, a high-elevation failure associated with a behind-dam abandoned mining area at the Jinsha Hydropower Station, this study systematically investigated the time-series deformation curves and historical failure processes before and after landslide mitigation. Multiple technical approaches were integrated, including field reconnaissance, unmanned aerial vehicle (UAV) photogrammetry, visual interpretation of optical remote sensing satellite imagery, and time-series InSAR analysis based on Sentinel-1A ascending orbit data. The key findings were as follows: ① Field investigations revealed that the 2018 landslide was primarily triggered by two factors: roof collapse of the underlying abandoned mining area and rainfall infiltration. ② Comprehensive analysis indicated that the tensile stress zone induced by mining-induced roof caving propagated from the slope surface upward to the crest, resulting in tensile cracking and subsidence at the landslide′s rear edge. Primarily influenced by self-weight, the rock-soil mass exhibited a tendency to move downward toward the free face. Gradual expansion and interconnection of the lower cracks and rear-edge tensile cracked eventually formed a continuous sliding surface. The failure mode of the Shanliangzi Landslide was classified as a "collapse-tensile cracking" retrogressive type. ③ Field surveys in 2024 identified newly developed cracks at the landslide′s front edge. InSAR interpretation results further confirmed that the slope, despite mitigation measures, remained influenced by the abandoned mining area and exhibited ongoing creep deformation characteristics. This study provides references for ensuring the long-term safe operation of the Jinsha Hydropower Station.