Bearing capacity and failure behavior of disconnectable coupling joint with double row wedges (DCJD) used in the prestressed internal bracing

Abstract

A disconnectable coupling joint with double row wedges (DCJD) is a crucial component of the prestressed internal bracing in subway foundation pits. However, only a few studies have been conducted on the bearing capacity of the joints; moreover, the yield load and compression stiffness of DCJDs are typically determined from experience. The aim of this study was to quantitatively determine the bearing capacity and propose accurate formulas for calculating the yield load and compression stiffness of DCJDs. Hence, a DCJD was selected from a foundation pit in Beijing, China, and loading experiments were conducted under axial force. Load–displacement and load–strain curves were obtained, and the failure modes of the joint were analyzed. The experimental results were verified through several finite element models. Subsequently, parametric analyses were performed to investigate the effects of the dimensions of the key position on the DCJD’s bearing capacities. Moreover, regression analysis was used to obtain the formulae for estimating the initial compression stiffness and yield load of the DCJD. Finally, the fitting formulae results were compared with the numerical and experimental results. The comparisons showed that the fitting formulae were highly accurate in estimating the bearing capacity of the DCJD.