Field Test Study on Controllable Shock Wave Pre-Cracking of Hard Top Coal in Liuxiang Coal Mine

Controllable shock wave (CSW) technology offers a promising approach for improving roof cavability and safety in underground mining, yet its field-scale mechanisms remain insufficiently clarified. This study develops and validates an optimized CSW pre-cracking procedure for hard top coal at the Liuxiang Coal Mine. A series of CSW-induced fracturing experiments were conducted across multiple boreholes under real operating conditions, and the causal relationships between loading parameters, induced fracture propagation, and mining performance were systematically evaluated. Segmented water injection leak detection was used to quantify fracture development in the No. 3 coal seam. The results demonstrate that CSW significantly enhances top-coal cavability: the proportion of large coal blocks was reduced by approximately 25%, and the average roof pressure step distance decreased from the baseline of 16.12–20.03 m to 13.12–13.82 m. These improvements indicate more efficient energy release, a more stable roof structure, and safer working conditions. Overall, this study provides a technically verified and operationally optimized CSW procedure, highlighting its strong potential to support safer and more sustainable hard top-coal mining.