Mine pressure disaster prevention and control below coal pillar in close-distance coal seam mining

During the mining of close-distance coal seams at the Majialiang Coal Mine, when the working face advanced beneath the residual coal pillars in the overlying area, severe dynamic pressure hazards in the mine were encountered.Using research methods such as theoretical analysis and engineering validation, the causative mechanisms of the pressure hazards were revealed.A segmented hydraulic fracturing weakening technology for the advance area was proposed and implemented in an engineering trial at the 14206 working face.The results indicated that, after applying the segmented hydraulic fracturing weakening technology for the advance area, the maximum and average pressure values encountered at the working face decreased by 14.2% and 7.3%,respectively, while the maximum and average values of the dynamic load coefficient were reduced by 16.4% and 10.9%,respectively.For the evaluation of the support system's effectiveness, the maximum vertical displacement of the hydraulic pillar decreased by 47%,with the final subsidence remaining within a safe range below 0.4 m, and the maximum roof subsidence in the working face roadway was reduced by 33.33%.The implementation of the segmented hydraulic fracturing weakening technology for the advance area effectively prevented and controlled severe pressure hazards induced by coal pillars.