Optimization and engineering practice of large-diameter drilling hole-anchoring hole spacing based on stress relief-support reinforcement cooperative effect

• 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.