ROCKFALL HAZARD ASSESSMENT IN CANYON AREAS INCORPORATING REGIONAL-SCALE IDENTIFICATION OF POTENTIAL ROCKFALL SOURCE AREAS

The Taihang Grand Canyon Scenic Area in Huguan County, Shanxi Province is one of the ten most beautiful canyons in China, but frequent rockfall events seriously threaten the safe operation of the scenic spot. By incorporating high-precision topographic information and geotechnical properties, the slope angle distribution method was used for identification of potential rockfall sources at regional scale. Moreover, the failure sensitivity index of rock masses was introduced to quantitatively describe the instability probability of potential rockfall source areas. Then, the empirical model Flow-R was used to simulate the diffusion range of rockfall movements to obtain the propagation probability and energy distribution of rockfalls. Finally, a two-factor evaluation model was constructed to realize the quantitative evaluation of rockfall hazards in the study area. The main conclusions are as follows: (1)The area of potential rockfall sources in the study area is 25.7 km²(35.7%) and is mainly distributed in strips on the steep walls of the canyon. Among them, the area of high sensitivity to rock mass failure is 3.3 km². (2)The high-hazard area of rockfalls in the study area is 3.22 km², which mainly threatens the tourist distribution area and traffic routes in the scenic area, especially the provincial highway S327 near the entrance of Hongdou Gorge. (3)The field survey validation results show that the application of the slope angle distribution method is efficient and accurate in identifying rockfall source areas, and the proposed two-factor evaluation model can provide a rapid solution for rockfall hazard assessment in canyon areas. The complete technical solutions of "regional potential rockfall sources identification-instability probability analysis-rockfall hazard assessment" proposed in this study can provide technical reference for the early identification and risk assessment of rockfall events in similar alpine valley areas.