Stability of dangerous rockmasses and prediction of rockfall trajectory: A case study at Wansui Mountain in Ganzi County of Sichuan Province

The hazardous rock zone on the Wansui Mountain slope in Ganzi Town, Ganzi County, has experienced frequent rockfalls over the years, posing a serious threat to the lives and property of residents below. Therefore, it is crucial to conduct stability analysis of the hazardous rock zone and rockfall trajectory prediction for the Wansui Mountain slope. Focusing on the dangerous rock zone of Wansui Mountain's slope, the geometric dimensions and 3D morphology of the zone were obtained using drone oblique photography combined with field surveys. The development characteristics of the dangerous rock zone and the distribution characteristics of the dangerous rock bodies were analyzed, and the stability of the dangerous rocks was assessed. Based on RAMMS-ROCKFALL, considering the geometric shapes of the dangerous rocks and the 3D terrain, potential rockfall trajectories after the collapse of the dangerous rocks were simulated.The results show that:The slope is generally intact, with the main instability modes being falling and toppling due to weathering. A total of seven dangerous rock zones have developed, which are in an unstable state under seismic conditions; the simulation provided the relationships between rolling and bouncing heights, speeds, kinetic energy, trajectories, and positions. By predicting the rockfall trajectories, the threat range and targets of the dangerous rock zone were determined. The prediction results indicate a significant threat to the houses and pedestrians on the streets below the slope of Wansui Mountain, and remedial measures should be taken as soon as possible.The research results indicate that the use of drone oblique photography is beneficial for the stability analysis of dangerous rock bodies on slopes, compensating for the blind spots of traditional surveys, and improving the efficiency and quality of the investigation. This provides a new approach for the investigation of dangerous rock bodies and rockfall trajectory analysis, which has positive significance for disaster mitigation technology research and the management of dangerous rock bodies.