Low-carbon effects of constructing a metro station with new pipe curtain method: A case study

By optimizing the connection method between adjacent steel pipes in the pipe curtain, conduct load-bearing capacity tests, while the construction sequence and support parameters were improved, the extended flange concrete-filled steel pipe curtain structure was formed. The carbon emissions of both the extended flange concrete-filled steel pipe curtain method and the pile beam arch method were calculated separately. Based on a bidirectional verification mechanism of top-down decomposition and bottom-up aggregation, the rationality of the system boundary was effectively validated, eliminating duplicate carbon emission calculations caused by fragmented construction processes. The research results indicate that: The welding of upper and lower flange plates + bolts connection method has the optimal bearing capacity, by integrating optimized measures such as the wing-reinforced concrete-steel pipe curtain structure, the pilot tunnel-rebar-steel pipe foot support system, and the steel pipe center column with top longitudinal reinforcement beams, the deformation control effectiveness of the extended flange concrete-filled steel pipe curtain method is further enhanced, while material consumption is reduced; The total carbon emissions of the extended flange concrete-filled steel pipe curtain method amounted to 4,305.55 tCO_2eq, representing a 10.55 % reduction compared to the pile beam arch method of this reduction, 76.12 % was contributed by the optimization of the support system. A carbon accounting system based on a bidirectional verification mechanism “unit project–subproject–unit process” was established, ensuring the accuracy of the settlement results. The optimized construction method proposed in this study better aligns with practical engineering requirements and national carbon emission reduction policies. A unique bidirectional carbon emission verification mechanism is employed to ensure the accuracy of calculated results, which may serve as a reference for related research.