Study on the Hierarchical Grouting Reinforcement Control of Low Permeability Surrounding Rocks of Deep Roadway

To solve the problem of grouting reinforcement of low permeability argillaceous surrounding rocks of deep roadway, the zonal failure characteristics of the surrounding rock and the mechanism and technology of hierarchical grouting reinforcement were studied by means of rock mechanics test, numerical simulation, and field test. Based on the stress environment of the surrounding rock of deep roadway, the uniaxial and triaxial compression mechanical properties of mudstone were tested. The results showed that the shallow surrounding rock of the roadway was in a state of uniaxial compression or low confining pressure, and the strength of the surrounding rock was low with splitting failure, whose fracture opening was large. The deep surrounding rock was in the state of triaxial compression, and the strength of the surrounding rock was high with shear failure, whose fracture opening was small. The rock mechanics test and drilling peep results showed that the surrounding rock was divided into the fracture development zone, micro-fracture zone, and fracture closure zone from shallow to deep of roadway. Based on the zonal failure characteristics of the surrounding rock in the deep roadway, the mechanism of hierarchical grouting reinforcement was put forward: Through the implementation of “ordinary cement, low pressure grouting” in the fracture development zone and the “superfine cement, high pressure grouting” in the micro-fracture zone, the groutability and strength of the surrounding rock have significantly improved, and the anchoring structure of the surrounding rock could be improved. According to the failure characteristics of the surrounding rock of the 1103 roadway, the slurry diffusion characteristics under different grouting pressures and grouting hole spacing were simulated, and the grouting parameters were determined. The field practice of hierarchical grouting reinforcement with “3 MPa pressure grouting for fracture development zone” and “12–15 MPa pressure grouting for micro-fracture zone” was successfully carried out, and the deformation of the 1103 roadway was effectively controlled.