Research On The Risk Control Technology Of Large Section Station With Horizontal Proof And Straight Wall Closely Crossing Underneath The Existing Tunnel

In recent years,more and more cities work out their short-term even long-term subway line network planning.During this period,it will encounter the problem of new subway station under through existing tunnel.As the most dangerous projects in the crossing existing tunnel,the closely crossing underneath project is a difficult problem and key research object in the subway construction.This paper based on the background of Changchun metro satellite square station and through theoretical analysis,case analysis,numerical simulation and field test studies the construction methods and risk control measures that large section station with horizontal proof and straight wall closes beneath the existing tunnel and settlement rules and risk control standards of the existing tunnel.the main work and research the results are as follows:(1)This paper analyzes the mechanism of stratum deformation and settlement mechanism of the existing tunnel in crossing underneath construction.It reveals the stress characteristics of the under construction,deformation transfer way and the defects of the existing tunnel and railway track caused by under through construction.(2)This paper get most suitable excavation method and station structure by studying the construction methods of large section subway station and different structures of subway station in closely passing existing tunnel.(3)Rely ling on the engineering background,this paper studies the settlement law of the existing tunnel that three crossing beneach construction schemes such as 4 hole cavern-pile method,6 hole cavern-pile method,8 hole cavern-pile method by numerical calculation.Then this paper uses analytical hierarchy process to select the most suitable scheme of the project.(4)Through the initial grouting reinforcement test,this paper optimizes construction process by advanced deep holes grouting reinforcement,initial supporting system,and applies numerical method to verify results,and gives the settlement control values of the existing tunnel.(5)This paper analyses measurement data of construction site and summarizes deformation regularity of the existing structure and railway track.Compared with numerical calculation,it could be feasible to numerical results to guild practical construction.And this paper gets a set of key technologies about large section subway station closely under through the existing tunnel,and provides reference for under-passing existing construction program.