Research of Increase Gas Drainage Efficiency with Slotted Charge Blasting

Proposed the method of slot cartridge hole blasting to improve the efficiency of gas drainage. First, by the mean of numerical calculation, we conducted the two-dimensional simulation study on the X-shape-slotted charge blasting in the coal. It was found that along the direction of the slot the perforative main crack formed, while in the other direction a dense network of secondary cracks formed, which improved the fluidity of the gas in the coal. Followed by a three-dimensional simulation study, it was found that near the gas drainage holes, the effective stress was greater than 40 MPa, while in the vicinity of free surface the stress wave attenuated severely. On the one hand it ensures of enough cracks in the coal, which facilitate gas emission, on the other hand it ensures the intactness of free surface in the blast, which enhances the security of gas drainage.