Low-carbon effects of constructing a prefabricated subway station using a trenchless method: A case study in Shenzhen, China

Abstract

The traditional open-cut construction method for subway stations poses significant social and environmental challenges, and a trenchless method represents a promising alternative. This study uses the construction of a subway station in Shenzhen using a trenchless pipe-jacking method, as a case study. The design concept and construction scheme of the station are presented in detail, and the technical benefits of the technology are analysed. To assess the low-carbon effects of the method, this study uses life cycle assessment (LCA) theory. The findings indicate that the greenhouse gas (GHG) emissions of the station constructed this way are 10.5% less than those of the open-cut cast-in-situ (CIS) method. This decrease is attributable to reduced GHG emissions of 9.39% and 20.14% from building materials and related to energy consumption, respectively, achieved by reducing material consumption and improving electrification. Soil reinforcement engineering at the launching and receiving shafts is a significant factor affecting 34.17 % of the GHG emissions of the trenchless method, primarily owing to the significant cement consumption. The trenchless construction method used for the middle part of the station, which is beneath a large box culvert section, can decrease GHG emissions by 52.66% compared with open-cut CIS schemes. This is due mainly to the avoidance of additional GHG emissions resulting from the relocation of large box culverts required before open-cut construction of the station. Trenchless method, therefore, offers many advantages in reducing emissions and generating social benefits in complex urban environments compared with open-cut method, making it an essential approach to assist sustainable underground space development.