Numerical Simulating Research on Orifice Pre-splitting Blasting in Coal Seam

Aiming at the actual problems such as bad effect of gas drainage, slow mining speed, high cost and so forth of drilling along layers in mining face of coal seam of low air-permeability but high gas-content, effect of orifice pre-splitting blasting on crack extending in coal seam was studied through adopting ANSYS/LS-DYNA software. Different diameters and depths of holes were set in the simulation, and groups were divided through using method of controlling variable volume. Results show that when depth of hole is fixed, with diameter of hole increasing, time for elements at the same location to receive stress shortens gradually, and when diameter of hole is fixed, with depth of hole increasing, time for elements at the same location to receive stress prolongs gradually, that is, the bigger the diameter of hole is, the more easily cracks extend in coal seam, and the deeper the hole is, the more adversely cracks extend in coal seam. This conclusion can provide theoretical basis for researching the gas drainage effect of actually applying orifice pre-splitting blasting.