Characteristics of deformation and failure with support countermeasures for expansive soft rock roadway crossing faults in the western region

To address the severe deformation and failure of roadway roof and floor encountered when crossing fault zones in coal mines in western China, this study takes the lower gateway of the 11E5-303 working face crossing the SF1 normal fault in Zhaohequan Coal Mine as an engineering case. A comprehensive investigation was conducted using field investigation, laboratory testing, numerical simulation, and engineering applications. The research aims to clarify the deformation mechanisms of the surrounding rock in fault-affected zones and to provide adequate control measures for roadway stability during fault crossing. Studies have shown that the roof and floor strata along the 11E5-303 Working face's adjacent roadway are primarily composed of siltstone, fine sandstone, and argillaceous siltstone, which are highly susceptible to water-induced softening and swelling, leading to a significant decrease in mechanical strength. This phenomenon is particularly severe near the fault, where substantial roof subsidence and pronounced floor heave are observed. Based on the Mohr-Coulomb failure criterion, the deformation and failure mechanisms of the surrounding rock under the existing support system were analyzed. The study revealed that the roadway surrounding rock within 10 m of the fault zone is subject to intense deformation and damage, with the hanging wall showing a significantly larger failure range than the footwall. Floor heave at the fault zone is also markedly greater than in other sections. These findings identified key support zones and critical reinforcement areas, emphasizing the need for early implementation of high-strength support systems within the fault-affected area to enhance stability. Targeted control technology for surrounding rock stability in fault-crossing roadway was proposed. After optimization, the roof subsidence was reduced by 68% and the floor heaves by 81% compared to the original support system. The optimized support scheme significantly improved the stability of the roadway, demonstrating apparent effectiveness. These results provide valuable guidance for roadway support design and stability control under similar geological conditions.