Highly prestressed NPR cable coupling support technology and its application in the deep roadway

Abstract

The stability control of deep roadways has always been a difficult problem related to the safe production of mines. This study took the -950 level substation roadway of the Wanfu Coal Mine in China as the project background to study a new support technology with negative Poisson’s ratio (NPR) cables as the core. Firstly, based on the mechanical properties of the NPR cable with a large constant resistance, a high elongation, and uniform full-length energy absorption, the highly prestressed NPR cable coupling support technology was proposed. Its mechanism was revealed, i.e., by strengthening the surrounding rock with a high prestress and releasing its deformation energy with a large constant resistance and a large deformation, the “stress compensation” effect of the NPR cables can be brought into full play so that coupling of the “support-surrounding rock” can be achieved. Secondly, the numerical model of the second-generation NPR cable was established by FLAC3D, which can realise the constant resistance and large deformation of the NPR cable and achieve the sequential breaking of the NPR steel strands during the deformation of the NPR cable. Numerical tensile tests verified its effectiveness. Finally, the NPR cable support scheme was designed through theoretical calculations and numerical simulations. After field application, the roadway deformation was constrained within 80 mm, effectively preventing engineering failures. This study may serve as guidance for similar projects.