Abstract: The mechanical properties of longitudinal joints in prefabricated two-wallin-one diaphragm walls are investigated through a case study on a metro station. The study seeks to understand the load transfer mechanism and failure mode of the sinking-inserting joints in these structures and to assess the bearing capacity and ductility of the joints. Furthermore, a full-scale bending test is carried out under simulated on-site assembly conditions. The research results indicate the following: (1) The cracking and separation between the CT-locks and concrete serve as critical indicators of the joints′ plastic behavior and ultimate bearing capacity. The tensile fixation of the CT-locks ensures the ductility of the sinking-inserting joints and contributes to the stability of the longitudinal structure in prefabricated two-wall-in-one diaphragm walls. (2) The sinking-inserting joints exhibit distinct three-stage developmental characteristics, with the moment-rotation relationship curve showing a bilinear pattern. The yield bearing capacity and the ultimate bearing capacity are approximately 215 and 265 kN·m, respectively, with the yield bearing capacity accounting for approximately 80% of the ultimate bearing capacity. The bearing capacity of the joint is approximately 30% of that of the continuous section. (3) Under the influence of CT-locks, the joints behave as hinged joints with ductile properties.

Key words: prefabricated two-wall-in-one diaphragm walls, sinking-inserting joint, CT lock, full-scale bending experiment, longitudinal joints, mechanical properties