Study On The Effect Of Construction Of Undercrossing Shield Tunnel On The Existing High-speed Railway Tunnel And Its Control Technology

The design and construction of the subway is faced with the new challenge that there is no case of undercrossing shield tunneling construction on the existing high-speed railway tunnel at present. Therefore, there is a positive significance to research on the influence and control standards of undercrossing shield tunneling construction on the existing high-speed railway tunnel. Based on the project of Changsha Metro Line3undercrossing Liuyang River Tunnel on Wuhan-Guangzhou High-Speed Railway, the control standards of operation safety of existing high-speed railway and its tunnel structure are discussed by reference to the relevant standards and experience in similar projects; By the means of theoretical analysis and3D numerical analysis, the response laws, influencing factors, construction parameter and construction measures of existing high-speed railway tunnel are also analyzed. The main content and conclusions of this research are as followings:(1) The undercrossing shield tunnel construction causes the change of both strata displacement field and stress field and leads to the deformation and internal forces moreover. The covering soil thickness, clear spacing, surrounding rock conditions, and construction parameters are proved to be the main influence factors of undercrossing shield tunnel construction. For a given project, the impact of the construction parameters should be the mainly focused.(2) Based on analyzing and summarizing relevant standards and experience in similar projects at home and abroad, the control standards of track irregularities of high-speed railway, deformation and stress increment of existing tunnel are given to ensure the safety of existing high-speed railway and its tunnel structure.(3) By the means of three-dimensional finite difference (FLAC3D), the process of undercrossing shield tunnel construction is simulated, and the changing laws of soil displacement, deformation and internal forces of the existing high-speed railway tunnel are analyzed. At the same time, the influences of covering soil thickness, clear spacing, surrounding rock conditions and construction parameters are also discussed and analyzed.(4) The influence of shield tunnel construction on the existing high-speed railway tunnel is analyzed on the base of ratio of ground loss.(5) An optimization design for the construction parameters and reinforcement measures are carried out, and the law of their influence and a reasonable range of those values are given. Finally, some pertinence measures are proposed according to the results obtained in this paper and the construction experience.There are60pictures,39tables and84references in this article.