Development Characteristics Of Dangerous Rock Collapse And Its Prevention Measures Where In The Mountain Of No1 Behind Cunda Dam At Kongyu Township In Kangding Country

The dangerous rock belt of Cunda river is located in the mountainous area of Kongyu Township,Kangding County,whose fissure is developed and integrity is poor.In the past two years,due to the effects of 4.20 Lushan earthquakes in 2013 and heavy rainfall,the deformation of the dangerous rock mass in the collapse area is intensified,and the collapse of the rock mass from the parent rock occurred,which endangers the people's life and property safety and the passing vehicles.Based on the geological conditions such as groundwater,weathering unloading,stratigraphic lithology,topography and geomorphology,this paper first comprehensively identified the spatial distribution and possible instability patterns and classification of dangerous rock bodies,and then carried out different Stability analysis and the potential characteristics of each stage after the collapse of dangerous rock,and finally put forward the targeted engineering control measures.The main achievements of this paper are as follows:(1)The lithology of the study area is dolomite,the joint is more developed,and the slope is steep,which is conducive to the development of falling rock.Based on the analysis of the factors influencing the collapse and development of dangerous rock,the main factors that have occurred in the study area are as follows.The inner factors include:the terrain and the lithology and structure of the rock mass in the study area.The external factors mainly include rainfall and groundwater action,earthquake action,weathering,gravity,human activity and plant root splitting.(2)According to the large number of on-site survey data,combined with the domestic and international classification of dangerous rock failure model,dangerous rock instability of the study area is divided into three modes:slip,dump and fall.The stability of the dangerous rock mass in three kinds of failure modes is analyzed qualitatively by using the flat projection,and then the model is established and the stability analysis is carried out by quantitative calculation.(3)The discrete element analysis software UDEC is used to simulate the stability of dangerous rock under different fissure water pressure.Through the control simulation of different height fissure water,it can be known that the fissure water is fractured and destroyed in the dangerous rock mass,which makes the fracture of the dangerous rock continue to expand.Under the strong rainfall or heavy rain,the fissure water pressure increases.As the fissure normal pressure increases,the dangerous rock structural surface continues to expand,and finally lead to collapse rockfall.(4)cite the predecessors of the collapse of rock and roll movement of the study and analysis,to determine the study area after the collapse of dangerous rock characteristics of the various stages of movement.Based on some traces of rock and stone trajectories and combined with the research data,the trajectories and motions of the collapsed rock fall in the study area were deduced.Then,the rock trajectories and characteristics of the rockfall were simulated by Rockfall software.The calculated results Can be targeted for the subsequent control measures to provide basic mechanical parameters.(5)Based on the summary of the various types of prevention and control measures and the applicability of the existing dangerous rock collapse,the spatial distribution of the dangerous rock mass in the study area,the topographic features of the possible caving path,combined with the characteristics of the falling rock movement and the position of the protection object,For the dangerous rock with I W1 seriousness and harm to the larger recommended active control measures,other dangerous rock body for passive protection.