Numerical Simulation and Field Practice of Pressure-relief Borehole to Prevent Coal Burst in Deep-seated Coal Roadway

摘要

Stress concentrated zones of deep-seated coal roadway, in heading direction of driving working face, were simulated with FLAC~(3D), at the same time, pressure-relief effect with strike borehole, separation of roof strata and bolt axial force variation were obtained. Simulated results show, after drilling pressure-relief borehole, stress concentration zones moved farther away from driving head to circumference from roadway cross-section section, stable distance from stress concentration zone to roadway driving head increased obviously and impact energy, around pressure-relief borehole, reduced markedly; with borehole to pressure-relief, increasing magnitude of roof separation and blot stress and corresponding peak values also reduced remarkably in the dynamic excavation simulation process. According to numerical simulation, borehole arrangement and bolting support scheme were designed, then, impact index in the field, was monitored and obtained with electromagnetic radiation method. The result shows the correctness of numerical simulation result and feasibility for field scheme design. Field trials show that pressure-relief method with large diameter borehole and high-strength yielding bolting support scheme is effective to reduce occurrence frequency of coal bombing in coal roadway and prevent roof collapse due to rock bolt failure by impact.