Study On Formation Mechanism And Prevention Measures Of Perilous Rock Of The Dam Area Of Yangfanggou Hydropower Station

As a kind of the worldwide of the universality geological hazard Perilous Rock often occur in a remote mountainous area,These regions have less permanent population but significant of engineering construction is concentrated,it is very obvious in the western region in our country. Frequent geological disasters hindered the major construction project progress,and tend to the state and the people bring huge property losses and casualties. In this paper,Take Perilous Rock of the dam area of Yangfanggou Hydropower Station as an example,on the basis of existing data and the field investigation,study of the formation mechanism of perilous rock.Based on the macro fracture mechanics mechanism of controlling Perilous Rock structure plane,Using different failure mechanism of calculation of the stability of Perilous Rock stability of Perilous Rock quantitative calculation,at the same time stability of Perilous Rock is qualitative analysis make a comprehensive analysis on the stability of Perilous Rock in the study area,As a thorough theoretical support effective prevention and control of Perilous Rock is provided. In this paper,complete contents and innovation points are as follows:(1)Firstly,this paper find out the overall characteristics of the developing of Perilous Rock in the study area through the detailed field data,and make clear the distribution regularities of all the types of Perilous Rock,and prove the relationships among topography and geomorphology,rock mass structure and distribution of Perilous Rock. In addition,Perilous Rock is divided into three types: sliding, dumping, fall on the basis of characteristic of its development,and developmental characteristics of monomer Perilous Rock also get the corresponding exposition in this paper.(2)Main factors that influence the formation of unstable rock are internal cause and external cause,mainly includes topography,litho logy,rock structures,weathering and rainfall,human activities,earthquake and so on.It is analysis that different factors affecting individual or combination to Perilous Rock’s information,development,destruction is different. In the period of geotectonic movement study,crust uplift and valley deeply cut. Both sides of the high and steep slope formation caused by stress redistribution and stress concentration effect leads to slope airport surface form stress concentration belt. Specific perform production and nearly parallel to slope table cracking surface and some of the new table structure surface. These are the controlling factors for the formation of Perilous Rock. Fracture surface and the existence of epigenetic structure leads to rock structure becoming loose. Rock structure in the outside world,gravity,weathering,rainfall,earthquake and artificial activities will be further damaged. Structural plane block through the gradual slope will stay gradually away from the parent rock,and at last it leads to the formation of unstable rock. Different combination relationships of structural planes can form Perilous Rock masses with different mechanisms of fracture. In order to know these mechanisms,this paper establishes generalized simulation models of Perilous Rock mass elements with the way of Mohr-Coulomb constitutive model by using the discrete element software of UDEC. And under the actual boundary condition,this paper finally gets the fracture mechanisms of the three deformations of Perilous Rocks---tenso-shear dumping,press-shear slipping and ripping to fall.(3) The calculation of basic theory of fracture mechanics of rock stability is mainly based on the control structural plane analogy to macroscopic crack. It focuses on the fracture toughness of the instability threshold effect. Through the analysis of the fracture toughness of rock and the corresponding operating mode control structural plane fracture strength factor,in order to achieve an accurate analysis of the stability of the Perilous Rock,and defined as the ratio and the fracture toughness fracture combined with intensity factor for the Perilous Rock stability coefficient. This article is based on the theory of fracture mechanics,and makes a quantitative calculation of the stability of Perilous Rock to the different failure mechanism of typical Perilous Rock. The calculation results show that three types of Perilous Rock in natural conditions in the unstable state. All stability coefficients of Perilous Rock reduce in different degrees under external force disturbance. Calculation results are more objective,sensitive and convenient for engineering. As the basis of the cutting degree of controlling structural plane of rock and the deformational degree,establish different types of stability of to the qualitative evaluation standard(the standard respectively by terrain slope,master combination of structural plane obliquity, master degree of structural plane is complete,the structure of the control surface open degree as the criterion,and the difference between different types of Perilous Rock stability criterion) qualitative analysis was carried out on the stability of Perilous Rock in the study area. In order to fully grasp the Perilous Rock stability in the study area,and the comprehensive stability of the Perilous Rock quantitative calculation and qualitative analysis,low stability of Perilous Rock is in almost stable condition,lower stability and extremely Perilous Rock in unstable state. It has good engineering suitability that the stability of Perilous Rock tallies with the qualitative analysis and quantitative calculation result. And statistical data verifies the close relationship of the stability of Perilous Rock and rock mass structure,slope. It is partly verified the reliability of the qualitative evaluation standard.(4) The study found that prevention and control of Perilous Rock is system engineering and the management of Perilous Rock is restricted and controlled by many factors. This paper establishes control principle of the Perilous Rock of hydropower high slopes under the overall consideration about engineering importance level, scale, construction conditions,the stability of Perilous Rock and combines the practical situation of the Perilous Rock of hydropower high slopes with it which is also based on the reference of existing controlling measures of Perilous Rock. In order to guarantee the practicability of the principle and apply it to the management of Perilous Rock field of Yang Fang gully hydropower station dam site area to reach the optimal control effect of Perilous Rock which is also satisfying the requirement of reasonable technology, safety, economic and applicable,the environmental protection and etc. At the same time it can be used as a reference for future prevention and control of hydropower slope of Perilous Rock. In addition,considering the tumbling characteristics of terrain steep and rock fall in the study area along the slope channel,this paper analyzes Perilous Rock movement characteristics in combination of rock fall and also explores passive fence layout.