Research On Unstable Failure, Movement Characteristics And Countermeasures Of Dangerous Rock Mass

The caving of dangerous rock mass was a kind of harmful physicogeological phenomenon occurred commonly in mountainous areas. In recent decades, studied on failure mechanism and engineering countermeasure of dangerous rock mass has been the focus and difficult problem of engineering geology in china.Taking the slope in front of Kangding Nationality Teachers College as an typical example, in this thesis, the author relatively sysmatically studied deformation characteristics, stability numerical methods of dangerous rock mass, movement characteristics of rolling rock in the different stages, numerical simulation analysis of rock movement state and track, contermeasures of dangerous rock mass based on the detailed analysis of the regional geological environment.Followings were the dissertation's main research work and conclusions:(1) The development of dangerous rock mass was a progressive process step by step. In this paper,the various influencing factors of dangerou rock mass development were analyzed in detail, which included not only topography, geomorphology,lithology and rock combination,but also weathering, erosion, cutting valley. Those were inducted into internal factors and external factors. The internal factors included the geological structure motion and the nature of rock itself;the external factors were mainly rainfall, earthquake, gravity, weathering and human activities;(2) By analyzing the historical background , the size and characteristics of the typical disasters, the thesis determined the main influencing factors of the dangerous rock mass deformation. Based on this, it took the main influencing factors as the coupling parameters to carry on coupling analysis and establish stability analyses model for the corresponding stability calculation of the danger rock mass in different failure ways.(3) Used the discrete element analysis software(UDEC), this thesis select a typical dangerous rock mass to analyze the stability influence of dangerous rock in the process of water pressure in fissures. On the one hand, continuous flow in the fissures would reduce the mechanical strength of the structural plane and cause the fissures developing in norm direction. The continuous expansion of fissures would eventually cause dangerous rock mass to failure.It was better to explain why avalanche disasters were more frequent during the continuous rain or rainstorms;On the other hand, with analyzing the entire action process of the water in fissures, we could see that the destruction of rock mass was a gradual accumulation process. In shorttime strong rainfall or continuing lower rainfall duration, the water leakage in fissures could be quickly. Therefore, it would not induce the ultimate destruction of dangerous rock mass;(4) Application of the moment friction theory, the energy conversion theory , kinematics and dynamics, this thesis elaborated the analysis and calculation method of rockfall in four stages including the initial displacement stage, the collision movement stage, the sliding movement stage and the rolling movement stage. The numerical simulation of rockfall movement had been completed by combining with the actual situation in study area.(5) After comparing the prevention and treatment benefits of SNS defence system with of the traditional defence engineering, we selected the passive SNS defence system as the main prevention and treatment measures.