Superior stability control of deep soft-rock roadways via NPR anchor cables: A numerical comparison with conventional PR support

Excavation-induced changes in the stress state of underground rock masses are the fundamental cause of surrounding rock deformation and failure. In deep roadways, the combined effects of high in-situ stress and large deformation in soft rock render conventional small-deformation Poisson's ratio (PR) materials incapable of providing continuous and stable high support resistance, thereby compromising effective control of surrounding rock stability. To address this limitation, this study investigates a novel high-strength, large-extension anchor cable exhibiting a negative Poisson's ratio (NPR) effect. Static tensile comparison tests were conducted between NPR and PR anchor cables, demonstrating that NPR anchor cables possess mechanical characteristics of high pretension and sustained support resistance. The coupling support principle of NPR materials and the failure mechanism of PR supports are systematically summarized. Through the judicious application of FISH programming language, the constitutive relationships of both NPR and PR materials were implemented and simulated in FLAC3D. Under identical engineering conditions, the contrasting failure behavior of NPR constant-resistance supports, and PR supports were clearly demonstrated via numerical simulation. This approach enables precise identification of weak zones in roadway surrounding rock and the timing of bolt fracture under PR support, offering new insights into the spatiotemporal failure mechanisms of roadway instability under specific engineering contexts, and thereby validating the unique advantages of NPR materials in terms of high strength and toughness.