DAMAGE CAUSES AND STABILITY EVALUATION OF EXTREMELY HIGH REMOTE DANGEROUS ROCK GROUP: A case study of Wufeng Mountain area in northeast Yunnan

Extremely high remote dangerous rock collapse is characterized by suddenness, fast speed, great potential energy, severe destruction force, strong impact and wide influence range. Five dangerous rock blocks are located on the southern slope of Wufeng Mountain in Zhenxiong County, northeast Yunnan. The strata are near horizontal and the topographic slope of collapse area is above 70°. The bare area of bedrock is 0.07 km² in collapse and dangerous rock area, with the height difference of 222 m from slope toe to top, the average height difference of 159 m for dangerous rock mass, and the maximum horizontal displacement of rockfall of 216 m, belonging to typical extremely high remote dangerous rock group. The qualitative and quantitative methods are used to comprehensively analyze 10 basic influencing factors of dangerous rocks and evaluate the stability combined with internal and external conditions. The results show that the five dangerous rocks have poor stability with the toppling-type damage mode. The high-speed remote dynamic collapse easily generates debris flows, which impact and flow in high speed as scattered fans. The large bare area and fragile eco-environment are in urgent need of treatment.