Abstract:
To address the high risk of rock burst and the limited pressure relief effect of large-diameter boreholes in front of the roadway during tunneling toward the goaf, which are caused by the superposition of the advanced abutment pressure of the roadway and the lateral abutment pressure of the goaf, this study takes the excavation of 72303 transportation roadway toward 72301 goaf in Tianchen Coal Mine as the engineering background. By combining theoretical analysis, numerical simulation, and field monitoring, the mechanism of rock burst induced by abutment pressure superposition is systematically investigated, and a collaborative pressure-relief and rock-burst-mitigation approach integrating “head-on pressure-relief boreholes and roof loosening blasting” is proposed. The results show that as the roadway approaches the goaf, a “peak-peak superposition” of the advanced abutment pressure and the lateral abutment pressure occurs, forming a high-stress concentration zone that accumulates substantial elastic energy and significantly increases the risk of rock burst. Theoretical calculations and simulations indicate that the influence range of the lateral abutment pressure is about 172 m, with its peak located approximately 95 m outside the goaf. After entering the zone within 50 m from the goaf, the stress concentration coefficient rises sharply. Roof loosening blasting enhances the overall pressure-relief effect by generating strong disturbances that promote the collapse of adjacent coal-seam pressure-relief boreholes, thereby optimizing the pressure-relief boundary. Field application demonstrates that after implementing the synergistic measures, microseismic energy and frequency decrease significantly, dynamic phenomena are markedly reduced, and safe roadway excavation is achieved. The research outcomes provide a theoretical basis and engineering reference for rock burst prevention and control in roadways excavated toward goafs under deep and complex stress conditions.