Construction of three-dimensional model and stability analysis of dangerous rock mass based on nap-of-the-object photogrammetry and LiDAR technology

The collapse of high-steep dangerous rock is a common geological disaster in the mountainous areas of China. However, due to the limitation of objective factors such as traffic difficulties, the efficiency of artificial geological exploration is low and the safety risk is high, and the investigation in some places is unreachable. Based on the Laoshucuo 3# high-steep dangerous rock mass in the Three Gorges Reservoir area, this study established an analysis method system of high-steep dangerous rock mass by integrating UAV nap-of-the-object photogrammetry and airborne LiDAR technology. The three-dimensional geological model of Laoshucuo 3# dangerous rock mass was constructed systematically, and the engineering geological characteristics of the dangerous rock mass were characterized. The results show that there are five structural planes in the dangerous rock mass of Laoshucuo 3#, with the widest weak layer of 27.30 m and the deepest cavity of 2.19 m. The collapse type is toppling collapse. The stability coefficient of the dangerous rock mass is 1.375 under the natural condition, which is in a stable state, and 1.01 under the rainstorm condition, which is in an unstable state and needs to be treated. The technical method in this study has good complementarity to the investigation of high-steep dangerous rock mass, providing a new investigation method for non-contact measurement, geological information acquisition, and stability analysis of high-steep dangerous rock mass, and technical support for disaster prevention and mitigation in the reservoir area.