Hexi Corridor Of Nanjing Yangtze River Floodplain Complex Stratum ShieldStudy On Comprehensive Technology Of End Reinforcement Construction

This research takes Nanjing metro line two TA07 site shield construction as engineering background, aiming at the West Yangtze River floodplain in the complicated stratum of shield driving tunnel construction. The paper focuses on the selection of reinforcement technology of soft soil in the end, construction, shield tunneling in frozen body and so on, on the basis of construction requirements, ensuring shield tunneling safely and smoothly.Combined with the project, according to shield originating in confined water sands, risk level and different geological, depth and confined water conditions, three shaft mixing method, high pressure jet grouting method, grouting method, precipitation method and freezing method were taken to end reinforcement, ensuring construction safety shield launching and receiving.Through the finite element analysis and the application of ANSYS software in simulation and analysis of freezing reinforcement, combined with the construction experience, the strength, rigidity and stability of freezing consolidation receiving end were analyzed, generating freezing hole arrangement, image rendering the frozen body reinforcement effect chart. Finally, frozen reinforcement and reinforcement effect were determined to ensure the safety of shield received, after receiving the shield and according to the actual monitoring, frozen body adopts natural thawing and timely thaw the frozen segment tracking grouting so that we could get the good control reinforcement section of ground settlement.It is the first time to research the construction of metro shield receiving with super freezing body reinforcement of shield end, the risks and the potential safety hazard were to be forecasted and analyzed reasonably. According to the relative position between shield and frozen body during tunneling process, different measures were taken, such as using the radial holes of shield machine to inject polyurethane, po uring water steam by screw conveyor in the front of the cutter head and in the soil chamber and shield tail heating, thus strictly control the risks in construction of shield received. Finally an example was verified for the prediction and the analysis, providing a reference for colleagues on shield in the frozen body.