Evolution Law and Control on Deviatoric Stress in Surrounding Rock of Internal Hole-Making and Pressure Relief in Two Sides of Deep Coal Roadway: A Case Study

Conventional drilling pressure relief technology destroys the rock integrity of the roadway-surrounding rock and support system in the anchorage area of surrounding rock at the same time as roadway pressure relief. To overcome the incompatibility between roadway pressure relief and structural support, an integrated control strategy combining anchorage reinforcement with pressure release was established. The distribution characteristics of the deviatoric stress field under different internal borehole parameters were investigated through numerical simulations, and the influence degree of each parameter is discussed. We constructed a similar model to verify the reasonable key parameters of pressure relief and evaluate the pressure relief effect. The conclusions drawn are as follows. (1) The sensitivity ranking of factors affecting pressure relief in the surrounding rock was determined as internal hole-making position > internal hole-making length > internal hole-making spacing. At an internal hole-making depth of 10 m, the peak deviatoric stress migrated to deeper regions, accompanied by a notable reduction in its distribution range. Hence, the stress within the roadway-surrounding rock was effectively released. (2) The internal deviatoric stress peak (si) and its corresponding location were identified according to the internal borehole-creation position. As the internal hole-making length increased, the positional transfer effect became notably stronger. Appropriately extending the internal hole-making length can thus create a compensatory buffer zone that accommodates the volumetric expansion deformation of the roadway sides. (3) By appropriately determining the position and length of the internal boreholes, reducing the spacing between them can substantially release high deviatoric stress. When the spacing was ≤4 m, the rock surrounding the borehole exhibited a low-deviatoric-stress state, suggesting that the deviatoric stress between adjacent internal holes was largely dissipated without elevating the stress level in the shallow surrounding rock. (4) A comparable simulation approach confirmed the feasibility of implementing internal hole-making and pressure relief measures on both sides of a deep coal roadway. Field engineering applications further demonstrated that the proposed “anchorage + pressure relief” cooperative control system can effectively restrain the continuous large deformation of the surrounding rock along the sidewalls in soft and fractured deep chambers. These findings offer an effective strategy for controlling large-scale deformation and failure of surrounding rock in similar deep roadways and provide valuable engineering insights.