Study on Pore Propagation Law of Deep-Hole Pre-Splitting Blasting in Outburst-Prone Coal Seams Under Combined Multi-Stress Action

The coal resource-rich areas in Guizhou Province are located at the overlapping junction of the southern part of the third fold and subsidence zones of the Neocathaysian structural system and the Nanling latitudinal structural belt. These areas are characterized by well-developed folds and faults, complex coal seam structures, high in situ stress, and poor air permeability, which lead to low-efficiency conventional gas drainage and failure to achieve the expected results. In terms of enhancing coal seam permeability and improving gas drainage and utilization, research is urgently needed on the permeability enhancement mechanism of deep-hole blasting in outburst-prone coal seams under combined multi-stress action. By analyzing the influence law of coal mass fracture evolution before and after blasting, developing an experimental device for blasting permeability enhancement under combined multi-stress action, and conducting research on the pore variation law of coal mass before and after blasting, it is found that in situ stress is negatively correlated with coal mass pores, while blasting and gas stresses are positively correlated with pores. This study provides a theoretical basis and experimental evidence for permeability enhancement via deep-hole blasting in outburst-prone coal seams and further supports the selection of reasonable parameters for field tests to improve the gas drainage efficiency of outburst-prone coal seams.