Key Takeaways & Executive Findings
- •• The optimal spacing between large-diameter drilling holes and anchoring holes increases linearly with the drilling hole diameter, achieving a synergistic effect within a specific range. • Both excessively small and large hole spacings impair the pressure relief effect, as vertical stress between holes increases nonlinearly with spacing changes. • Field practice at the 1208 working face reduced coal body drilling cuttings by 33% and roadway moving quantity by 19.2% after optimizing hole spacing from 0.55 m to 0.45 m. • The combined pressure relief-support reinforcement effect is critical for ensuring roadway stability and preventing rock burst in deep mining environments.
Abstract
Large-diameter drilling method is a prevalent method for preventing and controlling rock burst, and the spacing between the large-diameter drilling hole and anchoring hole is a critical factor influencing the roadway stability and relief effectiveness. In this study, a mechanical model for optimal matching between the large-diameter drilling hole and anchoring hole was established following the principle of synergistic control. The influence of large-diameter drilling hole diameter on the optimal spacing under the synergistic relief effect was investigated by integrating theoretical analysis, numerical simulation, and field practice. The results suggest that the hole spacing achieved a synergistic effect in a certain range when the optimal hole spacing increased linearly with the hole diameter. For instance, when the anchoring hole diameter was 20 mm, an increase in the aperture ratio from 5 to 10 brought about an increase in the optimal spacing from 0.25 m to 0.45 m. Additionally, the vertical stress between the large-diameter drilling hole and anchor hole increased nonlinearly under the condition of constant pore ratio but varying hole spacing. Both excessively small and excessively large hole spacings were detrimental to the pressure relief effect. In the engineering practice, optimizing the hole spacing from 0.55 m to 0.45 m in the 1208 working face contributed to reducing coal body drilling cuttings and the roadway moving quantity by 33% and 19.2%, respectively. This demonstrates that the pressure relief-support reinforcement synergistic effect should be fully considered in optimization design.
1. Introduction
With the increasing coal mining depth year by year in China, there are about 60 ultra-kilometer deep wells at present. However, the complex conditions, such as high ground stress and high mining disturbance faced by deep mining, have induced frequent rock burst, considerably restricting the safe and efficient mining in China [1 −3]. Pressure relief in large-diameter drilling holes and anchoring support technology are crucial means to prevent and control rock burst in roadways.
Pressure relief in a large-diameter drilling hole lowers the bearing capacity of the coal body in the pressure relief area by destroying its integrity while transferring the high-energy accumulation area deep into the surrounding rock. Anchoring anti-impact support improves the stress state of the surrounding rock by applying radial constraint force to the coal body within the anchoring range, allowing for a certain bearing capacity of the roadway’s shallow surrounding rock.
Large-diameter drilling holes and anchoring support are widely applied in the field of rock burst prevention and control, attributed to their synergistic effects of pressure relief and support [4−7]. Excessive studies have been performed on the pressure relief of the large-diameter drilling method and anchoring support principles [8, 9].
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GUO Wei-yao, WANG Xiang-yu, YIN Li-ming, ZHENG Yong-sheng, JI Xin-bo, LIU Guang-zhao, WU Zhen (2025). Optimization and engineering practice of large-diameter drilling hole-anchoring hole spacing based on stress relief-support reinforcement cooperative effect. Journal of Central South University. https://doi.org/10.1007/s11771-025-6032-1
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Frequently Asked Questions
What is the optimal spacing between large-diameter drilling holes and anchoring holes?
The optimal spacing increases linearly with the drilling hole diameter. For a 20 mm anchoring hole diameter, increasing the aperture ratio from 5 to 10 increases the optimal spacing from 0.25 m to 0.45 m, achieving a synergistic effect between pressure relief and support.
Why is hole spacing critical in rock burst prevention?
Both excessively small and excessively large hole spacings are detrimental to the pressure relief effect. Correct spacing ensures a synergistic interaction between the pressure-relief holes and anchoring support, enhancing roadway stability.
What were the field practice results at the 1208 working face?
Optimizing the hole spacing from 0.55 m to 0.45 m reduced coal body drilling cuttings by 33% and the roadway moving quantity by 19.2%, demonstrating practical benefits of the optimized design.
What methods were used in this study?
The study integrated theoretical analysis, numerical simulation, and field practice to investigate the effect of large-diameter drilling hole diameter on optimal spacing under the synergistic relief effect.
What is the synergistic effect of pressure relief and support reinforcement?
Pressure relief in large-diameter drilling holes reduces the bearing capacity of coal while transferring high-energy zones deeper, while anchoring support applies radial constraint to enhance shallow rock bearing capacity. Their coordinated design improves overall roadway stability and prevents rock burst.
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