Research and application of pressure relief mechanism and key parameters of large diameter borehole in deep rock roadway roof

Abstract

Large deformation disasters in deep-buried hard rock tunnels under high stress represent a major challenge for the safety and efficiency of coal mining. Traditional pressure relief methods often fail to reliably stabilize the surrounding rock. To overcome the limitations of conventional pressure relief techniques for deeply buried hard rock tunnel drilling, this study introduces a new pressure relief method for roof drilling and validates it through theoretical analysis, numerical simulation, similarity modeling, and on-site monitoring. The research examines how drilling in the upper tunnel affects stress release and redistribution in the surrounding rock of the lower tunnel, providing a scientific foundation for measuring stress transfer and the effectiveness of pressure relief. A multi-criteria evaluation system was developed to assess the efficiency of the new drilling approach, focusing on pressure relief performance, rock stability, and construction practicality. This system addresses the challenge of quantifying pressure relief effects in traditional methods and offers theoretical guidance for parameter optimization. The optimal drilling parameters identified are a hole length of 17 m and a spacing of 3.2 m, which effectively controlled the deformation of the surrounding rock when implemented in the field. This innovative technique successfully overcomes the shortcomings of traditional methods in deeply buried hard rock tunnels, greatly broadening the scope of drilling-based pressure relief and providing valuable insights for similar complex tunnel stabilization efforts.

Keywords

Large deformation / Roadway failure mechanism / Roof borehole / Borehole pressure relief / Deeply buried hard rock roadway / Surrounding rock control

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