The Technology Research Of Gas Pre-drainage Through Floor Cross-measure Boreholes Of11-2Coal Seam In Zhangji Coal Mine

Gas disaster is the main disasters in coal mine safety production process, which is a serious threat to the life safety of mine workers. On the basis of theoretical research, such as the coal and gas outburst mechanism, the coal gas flow regularity around borehole, borehole gas pre-drainage techniques,combined with the Zhang Ji11-2coal seam field test,this paper validates the gas extraction effect of borehole gas pre-drainage.Basic parameters of gas can be measured in combination with coal seam11-2of Zhangji coal mine of Huainan mining group is that the original coal seam gas pressure is2.14Mpa and gas content is11.42m3/t. Observed by three months,we can see the gas drainage radius in seam with pressure released is3.76m.Reasonable arrangement plan of drainage borehole has been analyzed according to drainage radius.This action makes gas drainage coalseem have no omission.Then the computational formula of drainage borehole reasonable space can be obtained.Base on the formula, an experiment was conducted about residual gas pressure and content measurement after gas pre-drainage in1123(1) bottom exhaust roadway. Through this process,the result can be obtianed that residual gas pressure is0.6MPa and residual gas content is4.205m3/t. On the basis of comparion of gas pressure and content before and after drainaging, and comparion of these two physical quantities’s residual with the outburst critical value,the paper has come to the conclusion that crossing borehole to pre-drainage gas technology can be used to eliminating ountbust.