Study on gas drainage boreholes with different space distances between boreholesaffected to pre-cracking blasting enhancement effect of deep boreholes

In order to study gas drainage boreholes with different space distances between boreholes,ANSYS finite element simulation software was applied to establish a physical model of a pre-cracking blasting influence range in a deep borehole. There were five operation performances designed to discuss the gas drainage boreholes with different space distances between boreholes affected to the pre-cracking blasting influence range in the deep borehole. The paper had a study on the gas drainage borehole with different space distances between boreholes affected to the expansion shape of the blasting cracking, an analysis on the point mass displacement of the inner wall in the gas drainage borehole and a final determination on the rational space distances between the boreholes. The simulation results showed that when the space distance between the boreholes was 4 m, the main cracking fractured would pass through the gas drainage borehole and the gas drainage borehole would have a collapse phenomenon occurred. When the space distance between the boreholes was ranging from 3～7 m, with the space distance between the boreholes increased, the gas drainage borehole affected to the cracking fractured in the seam would be steadily weaken. Although the space distance between the boreholes would be affected to the whole tendency of the cracking, but the whole permeability improved effect to the seam would not have obvious difference. The optimum space distance between the pre-cracking borehole and the gas drainage borehole with the ore-cracking blasting in the deep boreholes was 5 m.