Research On Key Technologies For Prevention And Control Of Dangerous Rock And Rockfall At The Entrance Of Tunnels In Complex And Dangerous Mountainous Areas

There are many plateaus,basins,mountains and rivers in western my country,and the geological conditions are harsh.Under such conditions,tunnel construction will inevitably encounter disasters such as dangerous rocks,rockfalls,and collapses,which will cause serious harm to tunnel entrances and railway lines.The special topography and geological structure of the complex and difficult mountainous areas make the rock mass abnormally broken.Due to its high altitude,thin atmosphere,strong sunshine,large temperature difference,low temperature,freeze-thaw environment,heavy rainfall,glaciers,frost heave and other factors aggravate dangerous rocks.Spalling,the geological characteristics of the complex and difficult mountainous areas include almost all the factors for the formation of dangerous rockfalls,and it is the most severely damaged area of dangerous rockfalls in the world.Therefore,based on the investigation of the slopes and rockfalls at the entrance of railway tunnels in complex and difficult mountainous areas,it is urgent to carry out research on the protection forms and control measures for dangerous rockfalls at the entrances of tunnels in complex and difficult mountainous areas to ensure the safe construction and operation of the line.Relying on the tunnels along the railway in the complex and dangerous mountainous areas,this paper uses the method of data research,theoretical analysis and numerical simulation to explore the protection forms and control measures for dangerous rockfalls at the entrance of the tunnels in the complex and dangerous mountainous areas.The main research results are as follows:(1)Through a large number of indoor analysis and statistics,it is obtained that the relationship between dangerous rockfall,landslide and fault structure in complex and difficult mountainous areas is not obvious.The distribution of dangerous rockfall and landslide is closely related to slope elevation and lithology,revealing that the complex The particularity of rockfall disasters in difficult and dangerous mountainous areas.Based on the analysis of the engineering environment and geological conditions of the supporting project,the stability control factors of the slope and dangerous rock have been identified.(2)A comprehensive evaluation method for the stability of slopes and dangerous rocks is proposed,and the stability evaluation results of slopes and dangerous rocks at the entrance of tunnels relying on the project are obtained.(3)Based on the conclusions of the analysis of the stability of dangerous rocks,the main research is on the protection forms and treatment measures for dangerous rocks at the entrance of tunnels in complex and difficult mountainous areas,and the principles for setting up tunnel entrances are put forward."Intercept,passive support" principle of comprehensive prevention and control key technologies.Based on the analysis of the stability of the tunnel entrance based on the project,the protection forms and dangerous rock control measures for the tunnel entrance of key slopes and dangerous rock sections are proposed.