Study On Risk Assessment And Prevention Countermeasures Of Dangerous Rock Mass

The dangerous rock mass has been thought of as a hot and difficult issue in the field of geological studies since 1980s. As the rapid development of the economy, human living space has been extended to the mountain area. Especially, with the building of highway, railroad and large-scale hydropower station in mountain area, the disaster of dangerous rock mass occurred more and more frequently during the past few years. Recognition of dangerous rock mass disaster has been focused on. In recent 20 years, many researchers did plenty of researching and got some achievements. Based on these researched results, this paper takes sample for the dangerous rock mass of Jinping I hydropower station, and studies the geological nature of the dangerous rock systematically. The main conclusions were represented as follows:(1) The dangerous rock mass definition and its implication was studied. Meanwhile, the formation condition, influencing factors, and builds classification system about the dangerous rock were analyzed.(2) Based on the investigation of the geological condition and the features of dangerous rock, distribution characteristics and relationship between geological conditions and dangerous rocks had been studied.(3) Based on the study and analysis of three-stage development process of the dangerous rock, five types of failure model of the dangerous rock were illustrated. Meanwhile, by studying the movement of the dangerous rock rolling stone experiment, this paper illustrated the dangerous rock's movement rules and influencing factors were studied.(4) The standard methods of stability evaluation and forecasting of dangerous rock mass were illustrated, which laid the foundation for stability analysis and evaluation. And based on the stability conditions, the dangerous rock masses were classified, into three categories: instable, basically stable and stable, and created relevant quantitative and qualitative evaluation criteria. By quantitative calculation and analysis of typical dangerous rock mass in the research area, the dangerous rock mass stability static analysis, UDEC, 3DEC and DDA numerical simulation were further explained for their usage of evaluation.(5) The dangerous rock's hazard evaluation methods were studied. Based on the analysis and illustration of the basic theories and concepts on dangerous rock mass evaluation, considering the influence factors, two index systems, about hazard evaluation were advanced: fuzzy integrated judgment, and 3-factors method. The later could evaluate dangerous rock mass only by analyzing the scale, stability condition and the movement path after destabilization of the dangerous rock mass. It was clear-guided, simple and practical, which would also shed light on the other types of geological hazards evaluation.(6) According to the development stages and risk grades, the risk of dangerous rock mass was divided into three degrees:â… ,â…¡,â…¢. The grading scheme was related to the choice of prevention countermeasures.(7) The ultimate purpose of studying the dangerous rock was to carry out prevention countermeasures. Firstly, this part expounded the principles of prevention systematically, which was important to the guidance of work. The project prevention measures of the dangerous rock were divided into active prevention and passive prevention, and detailed explanation was put forward. To prevent from dangerous rock mass, measurements could be taken either separately or combined together. Finally, based on the studies mentioned above, the prevention-and-cure method, prevention measures, and forecasting and evaluation to the prevention effectiveness were studied.