Analysis of the ground settlement control of a large span metro station in Dalian city using the Centre Drift Method

Tunnel design and construction require efficient technologies during all stages of a tunnel project. A group of appropriately selected parameters which may influence the environmental effects induced by construction is a pivotal factor for successful construction of the whole project, especially tunnelling in city. In this paper, an effective and extensive construction method for ground surface settlement control (i.e. the Centre Drift Method) is investigated by finite element analysis for use in Heishijiao Station, line 1 of the Dalian Metro in China. A parametric analysis was performed to investigate factors that may influence the Centre Drift Method, including the centre column spacing, the curvature radius of the vertical temporary support, the stiffness of the temporary support and the longitudinal distance for demolishing the temporary support. Synthetically considering the above analysis results together with the cost, time and machine for tunnel construction, optimal parameters were determined to reveal the effect of the Centre Drift Method tunnel construction on adjacent structures numerically. Later with the comparison of numerical simulation and in situ data, the accuracy of simulation was verified. It can be concluded that for an urban area above a large span underground space with a shallow depth similar to the Dalian area, the Centre Drift Method is effective and reliable for controlling ground surface settlement and reducing unfavourable impact on the environment.