Feature acquisition and stability evaluation of high dangerous rock mass based on oblique photography: A case study at Guanyinshan in Wanzhou , Chongqing Province

The Guanyin mountain dangerous rock belt poses a security threat to the Miaoya tunnel of the proposed Wankai section of the Enguang Expressway, as well as Zhuxihe Bridge and the neighboring residents. It is urgent to be investigated and controled. Traditional investigation and evaluation methods are difficult to implement on the high dabgerous rock mass. Basic geological information is obtained through geological survey, drilling sampling and experiments, identification, geometric feature acquisition and boundary condition analysis of the dangerous rock mass are carried out by oblique photography, stability analysis of the dangerous rock belts and the dangerous rock masses are carried out by stereographic projection method and rigid body limit balance method, respectively. Simulation is carried out by Rocfall software for unstable dangerous rock. The results show that the cliffs develop six main dangerous rock zones with a volume of 400−5000 m³, and the rock mass is controlled by two groups of joint surfaces and structural surfaces combination, the overall stability is poor, prone to fall and tipping; among them, the W3 and W6 dangerous rock masses are in an unstable state under heavy rain conditions, forming a rolling impact on the proposed project, and the kinetic energy is 5−12 kJ. The research results can provide design parameters for the selection of the control measures of the dangerous rocks in Guanyin Mountain, and provide reference for the investigation and prevention of high dangerous rock mass, it puts forward new idea on the use of aerial survey methods to improve the efficiency and accuracy of traditional geological surveys.