Simulated field assembly bending experiment and mechanical model of sink-insert joints for prefabricated two-wall-in-one diaphragm walls

Abstract

The prefabricated two-wall-in-one diaphragm wall (PTDW) represents a groundbreaking approach, integrating temporary enclosure with permanent structures into a single prefabricated wall, thereby reducing material usage by 45 % and shortening construction duration by 40 % through mechanical assembly. However, the bending performance of the CT lock-based sink-insert joints, facilitating efficient mechanical assembly, remains an under-explored technological challenge. This study addresses this gap by conducting a novel simulated field assembly bending experiment and developing a parameterized model to evaluate joint mechanics. Furthermore, the application and optimization of this technology in the Shenzhen Metro are presented. Key findings encompass: (1) The CT locks employed in this novel joint exhibit a characteristic of initial gaps, and full-scale experiment has revealed that cracks and separation serve as indicators of the elastic-plastic transition and ultimate bearing capacity. (2) Despite the initial gaps, the CT lock constraints effectively enhance the joint ductility and longitudinal stability of the PTDW. (3) A pivotal load-bearing feature of the sink-insert joint is its manifestation of ductile hinged joint properties under the constraints by the CT locks. (4) The proposed model underscores the benefits of multi-parameter optimization, achieving a notable 22 % reduction in steel consumption while maintaining both the bearing capacity and stiffness of the system. This research addresses critical PTDW joint challenges, advancing low-carbon and high-quality urban construction practices.