Investigation Method of Loose Radius in Deep Borehole Controlled Blasting for Outburst Prevention

In order to determinate the space between deep borehole for controlled blasting, thus the outburst danger in seam could be eliminated, with a theoretical analysis and a site test method, a comprehensive analysis was conducted on the principle and shortages of a method to investigate the loose radius of the deep boreho le controlled blasting with the gas flow index method, gas emission initial speed index method, drilling cuttings value index method, gas pressure index method, tracing gas method, elastic wave method and others. The results showed that due to the complexity of the outburst seam, the loose radius of the deep borehole controlled blast ing measured with different methods would have a certain relativity and deviation. A suitable measuring method should be selected according to the site actual requirem ent. Based on the analysis results and the site actual requirement in Pansan Mine, the gas flow index method was applied to obtain the loose radius of the deep borehol e controlled blasting with 4 m in Pansan Mine.