Abstract: To promote China′s Carbon Peaking and Neutralization Policy, provide data support for energy conservation and emission reduction of metro projects, and address the complex and cumbersome problem of greenhouse gas quantification process in the construction stage of metro deep foundation pit engineering, a modular calculation method for carbon emissions in the construction stage of metro foundation pit engineering is established based on the whole life cycle theory. Due to the fact that the metro foundation pits are temporary, the carbon emission calculation process is divided into three stages: upstream material production, foundation pit site construction, and material transportation. Furthermore, the greenhouse gas emissions during construction process of the 02B foundation pit and the pit in pit of the Beijing City SubCentral station comprehensive transportation hub project are calculated and analyzed. The results show that: (1) The CO2 emitted during the construction stage of 02B foundation pit and the pit in pit reached 20 498.50 t and 32 422.50 t, respectively. (2) The carbon emission in the construction stage of the metro deep foundation pit project is related to the construction method and support strength of the metro deep foundation pit.

Key words: railway engineering, foundation pit engineering; carbon emissions, full life cycle