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Coal Engineering ›› 2026, Vol. 58 ›› Issue (5): 57-66.doi: 10.11799/ce202605008

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Optimization and engineering practice of key parameters for large-diameter pressure-relief boreholes in highly-stressed mining-affected roadways

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  • Received:2025-09-22 Revised:2026-01-04 Online:2026-05-15 Published:2026-05-27
  • Contact: dengyan gaodengyangao E-mail:18175317599@163.com

Abstract:

Aiming at the engineering problems such as excessive stress concentration and severe roadway deformation caused by the superposition of multi-working face mining in the return airway of the 110 working face of Cuncaota No.2 Mine, this paper adopts the efficient control technology of large-diameter boreholes. Through theoretical analysis of the pressure relief mechanism and combined with FLAC3D numerical simulation, it systematically studies the influence laws of borehole diameter, depth, and spacing on the stress and displacement of the roadway side, clarifies the optimal pressure relief parameters and adjustment directions, and finally verifies the effectiveness of the scheme through engineering practice. The research results show that: (1) After drilling, the stress peak decreases and shifts to the deep part. The pressure relief effect is not obvious when the borehole diameter is too small, while the pressure relief area gradually expands with the increase of borehole diameter. However, the coal wall loses its bearing capacity when the borehole diameter is excessively large, so the optimal borehole diameter is determined to be 0.3m. (2) If the borehole depth is too small, there is no pressure relief effect. As the borehole depth increases, the stress peak decreases and shifts to the deep part, the pressure relief effect is enhanced, and the pressure relief range expands. When the borehole depth increases to 15m, the pressure relief effect no longer improves, and the optimal pressure relief borehole depth range is determined to be 9m~15m (Lp<Lh≤3.3Lp). (3) With the decrease of borehole spacing, the double stress cores between boreholes gradually evolve into a single stress core, and the stress forms are bimodal (separated state and transitional state), unimodal, and non-peaked in turn, with the displacement between boreholes gradually connected. When the borehole diameter is 0.3m, the optimal pressure relief borehole spacing is determined to be 1.0m~1.6m (2X0≤L2≤2X0+2D). Engineering practice verification shows that after pressure relief using the optimized parameters, the roadway stress tends to be stable, and the convergence of the roof and floor as well as the two sides decreases by 86.15% and 86% respectively, solving the core engineering problems of excessive stress concentration and severe roadway deformation. The research results provide scientific support and engineering reference for the control of similar high-stress roadways affected by mining superposition.

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