A study of key construction technology on metro station constructed by enlarging large diameter shield tunnel

A construction method that a running tunnel of two tracks is constructed by large diameter shield machine and moreover a station is built by shallow mining method to enlarge large diameter shield tunnel can be regarded as a new approach to solve the construction problems of metro engineering under complex environmental conditions. Taking Beijing metro line 14 project as the engineering background, the metro station is constructed by shallow mining method to enlarge large diameter shield tunnel. The construction scheme and technology measures that the large diameter shield machine pass through metro station are discussed in detail. A new method of shield machine passing through the metro station duct is put forward for the first time and broke the constraints of conventional model, which the metro station duct is constructed after the shield machine pass through metro station. The construction coordination contradiction between metro station and metro tunnel has been solved successfully. A new enlarging excavation method is put forward, which the station structure can be constructed by using the large diameter shield tunnel as the construction work platform and construction channel. The enlarged excavation method has been applied in the construction process of Gaojiayuan metro station and it will provide a solution method to the construction of metro station when the ground of station site cannot be taken up. By analyzing the key construction stages, the designing schemes such as the enlarged excavation method, K segment dismantled method and the steel support system in the shield tunnel etc, are optimized to ensure the safety of enlarged excavation and the metro station structure. The engineering practice shows that the construction risk for the metro station structure and the surrounding environment are controlled effectively. ©, 2015, Editorial Office of China Civil Engineering Journal. All right reserved.