Shield Beneath The Zhengzhou Railway Station, Beijing-Guangzhou Line, Surface Subsidence Expected And Control Technology

Build shield law is a method of subway tunnels, compared with covering method and under-cutting method, the advantages of shield tunneling is construction speed and the ground effect is small. Shield law applied to build subway tunnel, how to forecast and control the surface subsidence is an important problem. Therefore, combining with zhengzhou subway shield through zhengzhou railway station project. The excavation of shield tunnel is simulated by using finite element analysis software ANSYS, using random medium theory calculation surface subsidence value and summary analysis field measurement data. The strata longitudinal and transverse settlement and settlement of horizontal displacement rule is verified. The major work and results of the paper are as following:1.Becourse of the special conditions of the Zhengzhou metro shield in the railway station, the monitoring measurement, method and the subsidence monitoring standards and alert value is determined.2.Using numerical simulation, random medium theory analysis, the shield through the railway station has caused the surface subsidence value is expected, and better agreement with the measured data, and effective guidance to the construction and ensure the shield of shield construction safety.3. How to control the method of shield in zhengzhou railway station was put forward, including the selection of shield construction machine, cutter, direction control of the machine, waste of the improvement and synchronous grouting process, control method of the shield's initial and arrived,the head of the shield's reinforcement.these controls of the ground surface settlement or apophysis caused by shield are effective controls.