Experimental and numerical investigation on the bearing capacity of disconnectable coupling (DC) joints for prestressed internal bracing in subway excavations

Abstract

Disconnectable coupling (DC) joint is an important connecting device in support system, and its bearing capacity, which is usually inaccessible, has a crucial impact on the support system’s bearing capacity. In order to quantitatively study the bearing capacity of a DC joint and propose relatively accurate formulas for calculating its yield load and compression stiffness, indoor axial loading tests were carried out on three DC joints in this paper, and a series of numerical simulations was performed by using the finite element method (FEM) of ABAQUS. Firstly, load-displacement curves, load-strain curves and failure modes of three joints were obtained. Secondly, the numerical results were verified by experimental results in failure modes and load-displacement curves. Subsequently, parametric studies were conducted to analyze the influence of the steel wedge dimensions, steel tube wall thickness, middle-rib plate height and middle-rib plate shape on the yield load and initial compression stiffness of the DC joints. Finally, calculation formulas for estimating accurately the yield load and initial compression stiffness of the DC joints were obtained.