Study on parameter optimization of deep hole cumulative blasting in low permeability coal seams

Coal seam gas extraction is an important means of exploiting and utilizing gas resources, as well as a means of preventing coal mine disasters. To improve gas extraction efficiency in high gas and low permeability coal seams while ensuring blasting security, deep hole cumulative blasting parameters were optimized. ANSYS/LS-DYNA software is used to establish a 3-dimensional cumulative blasting model. By comparing and analyzing the blasting stress nephograms, stress time-history curves, and crack expansion curves, the optimal blasthole diameter, charge position, and charge length are obtained. Based on the numerical simulation results, a field test was carried out in the No. 10 coal seam of the Pingdingshan coal mine. The test results show that after cumulative blasting, the gas concentration was increased by an average of 2.25 times, the gas purity was increased by an average of 3.78 times, the permeability coefficient of the coal seam was increased by 21 times, and the effective radius of blasting was up to 7 m. The positive effects of deep hole cumulative blasting parameter optimization on the pressure relief and permeability enhancement of a high gas and low permeability coal seam were determined, which can provide a reference for other similar working faces to implement this technology.