Study on Mechanical Properties and Control Technology of Surrounding Rock in the Fracture Zone of a Roadway

We aim at the problem of the large deformation and difficult control of surrounding rock when passing through a fault fracture zone in the centralized rail transportation lane along the south wing of Xinyi Coal Mine; the stress environment and failure mechanism of surrounding rock are analyzed through field investigation, numerical simulation, and field industrial test. The instability of the surrounding rock in the fault fracture zone was considered to be the result of the joint effect of the surrounding rock fracture development, lithology differences, water gushing occurrences, low strength of the original support, high in situ stress, and fault-related tectonic stress. Rock blocks are collected on site at the fracture zone, and the remoulded samples are prepared for mechanical experiments in the laboratory. The basic mechanical parameters of the roadway passing through silty mudstone, sand-mudstone interlayer, and fine sandstone were analyzed. A three-dimensional model is established to analyze the distributions of the stress, deformation, and plastic area in the surrounding rock mass after the tunnel passes through, considering both a single-rock mass and a multilayer-rock mass. Based on the above analysis, the “closed support + shotcrete + grouting + anchor mesh cable coupling support” is proposed. Three stations were arranged on site to observe the mine pressure, and the field industrial test shows that, within the 100 days of observation, the maximum roof-to-floor convergence is 38 mm, while the maximum horizontal convergence is 56 mm. The overall reinforcement effect of the roadway is good, the surface is smooth, and there is no phenomenon of concrete cracking and bolt fracture.