Research On Design Method And Construction Technology Of Arch-Cover Method With Double Superimposed Support

In recent years,with the rapid development of China's national economy and the continuous progress of urbanization process,the number of urban population and vehicles increased rapidly and urban traffic pressure doubled.In order to effectively alleviate the increasingly prominent urban rail traffic congestion,urban rail transit construction was developed rapidly.The construction of urban rail subway station usually adopts the method of open excavation and cover digging,but because it often causes a lot of problems such as pipeline relocation,greening migration and traffic congestion,the proportion of subsurface excavation method in some underground cities such as Chongqing,Xiamen,Qingdao,Dalian is getting higher and higher.In the engineering practice of super large section mined underground metro station in stratiform rock strata,arch-cover method with double superimposed support is first applied to the Chongqing railway line 5 wind West Road station.The related design theory and construction technology are not mature.Therefore,it is necessary to research the arch cover method for the super large section mined underground metro station.The key construction technologies are used to guide the construction of Chongqing rail transit project,and provide reference for similar projects in China.In this paper,we take the Feng Xi Road Station of line 5 of Chongqing rail transit as the research object,and carry out corresponding theoretical and numerical analysis.1.Considering the bearing mechanism and applicable conditions of double deck overlapped initial support arch cover method,considering the anisotropic characteristics of layered rock mass,the 3DEC discrete element software is used to simulate and analyze the damage characteristics,and the bearing model of the arch foundation is studied theoretically,and the average set calculation formula of the base bearing capacity of the double layered arch cover method is given.2.Equivalent treatment of C and phi values of double layer laminated arch cover method in horizontal layered rock stratum is carried out.At the same time,the lateral pressure coefficient lambda is amended to get the calculation method of double deck overlapped initial support arch cover method,and the structure calculation model and the calculation model of the side wall structure of the double layer superimposed initial support arch cover method are established.A double deck superimposed arch cover method is designed.3.The construction technology of double deck overlapped arch cover method is summarized,its construction process,construction process and key factors are introduced.The micro differential initiation technology is put forward,and the suggested values of blasting parameters are given,and the safety control standards of blasting vibration speed,flying stone control and shock wave are set up.Based on the optimization analysis of double deck superimposed arch cover method,the key steps of double deck superimposed arch cover method are determined.4.The monitoring measurement technology of double deck overlapped arch cover method is put forward,and the monitoring content,monitoring section,monitoring point layout scheme,monitoring cycle and frequency are given,and the corresponding safety control datum is put forward,and the measured data are analyzed on the basis of the project.