Parameter Design Method for Destressing Boreholes to Mitigate Roadway Coal Bursts: Theory and Verification

Borehole destressing is one of the most widely used techniques for mitigating coal bursts. Understanding the working principle of destressing boreholes, exploring the main efficiency factors, and proposing a quantitative method for determining the drilling parameters for coal burst control are essential for maximizing coal burst control. This study establishes a unified damage mechanics model of borehole bursts (that is, dynamic collapse in boreholes) and roadway coal bursts, deduces the critical indices of borehole bursts, and identifies the main factors. The theoretical relationship between the critical stresses of borehole burst and roadway coal burst is quantitatively explored, and a theoretical criterion for borehole effectiveness in coal burst control is proposed using the critical indices of borehole bursts. Finally, a design principle, determination method, and calculation formulae for the drilling parameters, which are directly related to the roadway burst risk state, coal seam thickness, coal properties, and drilling size, are proposed. The optimized drilling parameters of typical coal burst mines in Hebei and Inner Mongolia verify the engineering applicability and effectiveness of the proposed design method. This study proposes a quantitative determination method for destressing drilling parameters that supports coal burst occurrence theory. Critical conditions for borehole bursts, directly related to the mechanical properties of coal and borehole size, are theoretically provided.Theoretical relationship between boreholes and roadway coal bursts is explored.Quantitative description of the borehole destressing principle to mitigate coal burst is provided.Theoretical criterion for boreholes to mitigate coal bursts, which is directly related to the critical conditions of borehole bursts, is provided.Quantitative method for determining the drilling parameters to mitigate coal bursts is proposed.