Objective In coastal developed regions, the construction of rail transit projects in reclaimed land areas is becoming increasingly common. If the enclosure structure of a metro station is constructed after land reclamation, the construction will not only be subject to the adverse effects of deep soft soil layers, but also face the prolonged construction period issue. If the above structure is constructed concurrently with the land reclamation project, it must be taken into account to retain the reclaimed sediment and seawater. To ensure the safety of foundation pit construction, it is necessary to study enclosure structure schemes for metro stations in reclaimed land areas.

Method  A comprehensive comparison in terms of construction duration, construction risks, land use, flood control/drainage, resource utilization, and engineering investment, is conducted between the scheme of constructing the enclosure structure after land reclamation, and that of the concurrent enclosure structure construction with the land reclamation project. For different enclosure forms, the displacement and safety factors of the cofferdam during the reclamation process are simulated and calculated to determine the safety of the station enclosure structure. The safety and feasibility of the metro station enclosure structure are verified through on-site construction monitoring data.

Result & Conclusion  After comparison, the cofferdam plus bored pile retaining structure in the above-mentioned concurrent construction scheme is found to be optimal. This scheme enables concurrent construction of the land reclamation project and the metro station, featuring low engineering risks, high efficiency and convenience, and reasonable engineering investment. Simulation calculations and on-site monitoring results indicate that the cofferdam plus bored pile retaining structure is safe and reliable. As it utilizes only conventional engineering materials, the structure demonstrates strong engineering feasibility.