Low-carbon efficiency assessment for Hong Kong's oceanic artificial cities applying the novel prefabricated diaphragm wall technology

Abstract

Oceanic artificial cities built by reclamation are vital for addressing the future sustainable development of land in Hong Kong. However, traditional cast-in-situ (CIS) construction methods face issues such as significant environmental impacts and low durability, making it challenging to meet the requirements of low-carbon and resilient development. To address these challenges, a novel low-carbon construction technology for oceanic artificial cities is proposed: prefabricated two-wall-in-one diaphragm wall (PTDW). This study aims to address the comprehensive assessment and decision-making issues of greenhouse gas (GHG) emissions and load-bearing performance. First, the adaptability of PTDW technology to oceanic artificial cities is introduced. Second, the Carbon-mechanics Dual-control Assessment Model-Section level (CDAM-SL) is established. Finally, CDAM-SL is used to assess the GHG reduction efficiency of construction technologies for oceanic artificial cities. The results reveal the following key findings: (1) The Bearing Property Indicators (BPI) of the PTDW-Cavity scheme surpass the CIS scheme across the construction and operation phases. (2) Comparing to the traditional CIS scheme, the GHG emissions of the PTDW-Cavity scheme are reduced by 33.31% (8.65 t CO2e). This reduction is primarily attributed to PTDW technology, which eliminates the temporary enclosure structure construction. Furthermore, the refined PTDW technology significantly decreases the GHG emissions of precast components and enhances drainage performance. (3) The GHG reduction efficiency of the PTDW-Cavity scheme consistently outperforms the CIS scheme across both phases. Consequently, PTDW technology demonstrates significant advantages in load-bearing performance and GHG emissions reduction. The research findings provide a theoretical foundation and applicable tool for the comprehensive assessment and decision-making of low-carbon construction technology for oceanic artificial cities.