Evaluating the GHG reduction efficiency of underground construction technology: Application of a novel prefabricated diaphragm wall technology

Abstract

The necessity for low-carbon underground structure construction in urban sustainable development is clear. Despite widespread green construction techniques, cast-in-situ (CIS) construction is still common in underground projects, presenting significant environmental challenges. Consequently, this study presents the Prefabricated Two-wall-in-one Diaphragm Wall (PTDW), a single-walled scheme, and investigates its GHG reduction efficiency. First, the technical advantages of PTDW were introduced in detail. Second, the Carbon-mechanics Dual-control Assessment Model (CDAM) was constructed to evaluate the GHG reduction efficiency of underground construction techniques. Finally, CDAM was used for a comparative analysis of single-walled and traditional double-walled schemes. The research findings are as follows: (1) The vulnerability of the prefabricated single-walled scheme is not inferior to the CIS double-walled scheme. (2) PTDW technology reduces GHG emissions intensity by 24.96% compared to traditional CIS construction. This reduction mainly results from avoiding traditional CIS temporary measures. (3) Across all restoration levels and areas, the single-walled scheme's GHG reduction efficiency consistently exceeds that of the double-walled scheme. PTDW technology offers significant advantages in structural resilience and GHG reduction efficiency. It also reveals that PTDW technology not only reduces GHG emissions intensity but also enhances the GHG reduction efficiency. These findings provide both a theoretical foundation and a practical tool for evaluating the GHG reduction efficiency of underground structural construction technologies.