Research on the anchoring instability mechanism and bidirectional deformation control of stratified surrounding rock roadway

To address anchorage failure caused by shear fracture of anchor bolts and cables, this study uses a coal-mine roadway as the case background and investigates the instability mechanism of the anchorage system through field observations, numerical simulations, and double-shear tests, with special attention to the evolution of relative lateral displacement—the primary source of shear load. The results show that the relative lateral displacement curve exhibits periodic oscillations with decaying amplitude, with lateral movements across bedding planes being the main source of shear load. Mining-induced stresses significantly amplify bidirectional displacements, with the roof showing the strongest response. The roof's peak relative lateral displacement exceeds 30 mm, over 70% of which occurs within 2 m. The insufficient shear capacity of the original support components is identified as the main cause of anchorage system instability. In soft rock, Anchor Cable with C-shaped tube (ACC) provides 38.9% greater inherent shear resistance than conventional cables. After clarifying its lateral and longitudinal reinforcement mechanisms, an ACC-based bidirectional deformation control strategy is proposed. Compared with the original system, the ACC system enhances shear resistance by 24.1% and reduces longitudinal and relative lateral displacements by over 23% and 19.8%, respectively. Field tests further confirm that this ACC-centered bidirectional control strategy effectively mitigates the adverse effects of shear loading and enhances roadway stability. Overall, the findings highlight the critical influence of lateral displacement on rock structure stability, extend the analytical framework for anchorage instability, and offer valuable guidance for deformation control in similar geological conditions.