Engineering geological characteristics and risk assessment of the Duochuka large bedding rock ancient landslide in Nagqu, Tibet

Abstract

The geological environment in the transition zone between the northern Tibetan Plateau and the high mountain gorges of eastern Tibet is complex, and the prevention and control of landslide hazards are central issues for regional engineering construction and disaster prevention and mitigation. This study focuses on several large, stratigraphically parallel rock-mass ancient landslides at Duochuka in Suo County, Nagqu City, Tibet. Through field geological surveys, drilling, and InSAR time-series monitoring, the spatial morphology, material composition, structural characteristics, and deformation and failure patterns of the landslides were systematically investigated. A three-level fuzzy comprehensive evaluation model, comprising the two core dimensions of hazard and vulnerability, was constructed to perform a quantitative assessment of landslide risk. The results indicate that the Duochuka landslide is currently in a generally stable state, with only localised deformation and failure occurring in the shallow surface layer of the foreland; the comprehensive risk level of the landslide is Grade II (moderate risk). These findings provide a scientific basis for the monitoring, early warning, and disaster prevention and mitigation of this landslide, and may also serve as a reference for the risk assessment of similar stratigraphic rock landslides in the canyon regions of the Qinghai-Tibet Plateau.