Key Technologies of Large Diameter Shield Tunnel Undercrossing High Speed Railway Bridge
Based on the large diameter shield of Suzhou Tongjing Road North Extension project undercrossing the bridge pile foundation of Shanghai-Nanjing high speed railway,the numerical simulation was carried out on the integrated stratum reinforcement treatment of isolation pile combined with MJS(Metro Jet System)grouting before shield undercrossing.The shield active construction control measures of the undercrossing process were also verified in practice.The results show that,the displacement of the bridge pier can be effectively controlled by the isolation pile combined with MJS grouting reinforcement,and can be reduced to 6%~10%of that without taking measures,which meets the control requirement of 2 mm.Combined with the shield active construction control measures,such as excavation parameter control and injection of clay shock synchronously,the displacement of bridge pier is stable during the shield undercrossing,and the measured maximum displacement in each direction does not exceed 0.5 mm.These prove that the measures in this paper are valid and can provide reference for similar projects.