The Study Of Design Supporting Parameters And Stability About Carbonaceous Shale Tunnels In Cold Regions

Jiangluling tunnel was built at the Qinghai-Tibet Plateau with an altitude of over 4300 m.The geographical environment is very bad.During construction,it is found the rock characteristic of the tunnel is the cold zone carbonaceous shale that lower level and easier weathered after the rock shale exposed.The tunnel rock appears very large deformation and even landslide after the tunnel excavated.The ultimately result is seriously delayed of the progress and cost increased.Large deformation of the tunnel is a difficult problem to solve in the process.There have not yet any good solutions now.Although there have been some studies on large deformation,the content of the study is still relatively lack.And the study of large deformation are aimed at tunnels in the general areas,but it is researched less in high altitude cold regions.So the design and the construction are only based on experience,engineering analogy and the measured data analyze to control the deformation by changing the construction method or supporting parameters.But in the early stage of the project,if the construction method used is not reasonable or the support parameters are too small,there will be serious risk in the construction.In order to solve the problem of landslideby large deformation of the carbonaceous shale tunnels,and collect more information on design and construction for the future tunnel projects which have the same rock characteristic,the research about carbonaceous shale tunnels in cold regions should be carried out,based on Jiangluling tunnel.First,the rock pressure's Calculating formula of carbonaceous shale tunnels in cold regions should be discussed by summarizing the calculation method of rock pressure,choosing out some methods suitable for deep buried tunnelsand usingthese methodsto calculatethe rock pressure of Carbonaceous shale in cold region.Then the pressure range through the measured data and simulation should be compared with the calculating resultwhichis the closest to the pressure range based on calculating formulacorrect the parameters in the formula.Second,to analyze the supporting parametersbased on experience and related professional skills to elect the range of suitable carbonaceous shale rock's supporting parameters,optimize the range combining with the measured data,contrast the supporting effect on original parameter and optimized parameter by simulating.Then consider the question of the secondary lining's safety reserve,assuming all of the load loading on the secondary lining,calculating the internal force of secondary lining by load structure method and stratum structure method,check the strength based on the more disadvantageous force state.The last,the stability's analysis of rock.According to the measured data of rock's deformation and convergence,obtain the maximum and daily variation of the deformation and convergence when the rock is destroyed,get the judgment if the rock could stable.In addition,the factors affecting the stability of surrounding rock are analyzed and suggestions are proposed,to provide reference resources for future tunnel engineering practice.