Abstract:

Stability control in soft rock roadways remains a critical challenge restricting the development of many coal mines in China. To address the support difficulties in the New Shanghaimiao mining area, we used field investigation and numerical simulation to clarify the deformation characteristics of soft rock roadway surrounding rock and reveal the mechanism of large floor heave. A mechanical model and analytical method for the roadway floor were established using the limit equilibrium principle. We then proposed a new support design using floor micro-piles and optimized the support parameters. The results show that groundwater significantly weakens the floor strata, and when combined with high mining - induced stress, the surrounding rock undergoes progressive failure under a high stress-to-strength ratio. The self-bearing capacity decreases beyond the support capacity, leading to shear failure and large-scale floor heave. The proposed floor micro-pile support effectively reduces the unbalanced thrust in the floor and improves stability. The greater the unbalanced thrust, the larger the micro-pile forces and the required reinforcement area, both increasing linearly. Conversely, increasing the micropile diameter reduces the forces and required area in a power-law manner. These findings were validated by field industrial tests, providing theoretical and technical guidance for surrounding rock control in the Shanghaimiao mining area and other soft rock coal mines.