Study on Underground Excavation Construction Technology of TBM with Tunnel First Excavated and then Expanded into Platform Based on Double Side Drift Method

In order to further improve the stability of TBM excavation passing through the underground station, this paper takes the Hemu Road station of Chongqing Metro Line 5 as the research background, and uses the numerical simulation software FLAC 3D to study the process optimization of TBM construction technology combined with double side drift method. The results show that: compared with the step by step construction of tunnel first excavated and then expanded into platform combined with double side drift method (working condition 1 ~ 5), the synchronous construction of tunnel before station combined with double side drift method (working condition 6 ~ 8) generally has less impact on surface settlement, final deformation of station, segment deformation and stress. Among them, the clearance convergence, segment deformation left inverted arch floats upward) and stress of working condition 8 are the minimum values, which are 1.87 mm, 0.16 mm and 0.595 MPa respectively. Compared with other methods, the clearance convergence, segment deformation and segment tensile stress of station structure are reduced by 59%, 50% and 40% respectively under working condition 8. It is recommended to apply the inverted edge construction sequence of synchronous construction in TBM excavation combined with double side drift method.