Research on optimization of drilling pressure relief scheme for residual triangular coal pillars

Based on the residual triangular coal pillar at the 1305 working face of a mine, this study employed numerical simulation to compare two pressure relief schemes with borehole depths of 30 m and 50 m, with field validation conducted under site-specific conditions. The results indicate that the 30 m-deep boreholes achieved a significant pressure relief effect on the residual triangular coal pillar, substantially reducing both the stress and displacement deformation of the surrounding rock of the roadway. In contrast, the 50 m-deep boreholes induced overlapping secondary pressure relief zones in the central part of the coal pillar. This led to a reduction in the load-bearing capacity of the central zone, transferring high stress toward the edges and resulting in an unsatisfactory overall pressure relief effect. Compared to the stress state of the surrounding rock without pressure relief measures, the 50 m scheme not only failed to reduce the stress and displacement but even caused a certain degree of increase. This further underscores the critical importance of optimizing the design of pressure relief schemes in rockburst mines.