| Gaocheng coal mine of Zhengzhou Coal and Electricity Group has great difficulties in gas management for 25091 sub lane coal mine roadway(north)mining area of the main mining coal.The coal seam has a monoclinic structure,the thickness of coal seam is 2.5?4.5m,the average is 3.5m,and the angle of coal seam is 11?17°,the average is 14°,the permeability coefficient of coal seam is 0.0053m2/(MPa2·d),and the gas content reaches 17.25m3/t and the original gas pressure of the largest 10.34MPa.Therefore,according to the characteristics of coal seam permeability,gas content,gas pressure,drainage difficulty easily induced gas accidents,the 25091 side lane(North)coal region as a test area,the deep hole pre splitting blasting strengthening antireflection drainage technology for gas treatment.Through to the domestic and foreign fracturing blasting technology and strengthening antireflection mechanism were summarize,based on theoretical study,numerical simulation and similarity simulation combining the test scheme and the scheme of practical investigation,after optimization in Gaocheng 25091 sub lane(North).The coupling coefficient Kd=1.2533 is obtained by calculating the available blasting parameters of the 25091 sub Lane(North Section),and the radius of the single hole blasting crack is 4.6m.At the same time,the influence of the different positions of the blasting holes on the formation of the blasting crater is compared with the numerical simulation of Ls-Dyna,and the radius of the crack is investigated by using the interface charge of the coal seam.The coal rock interface blasting in coal seam blasting with respect to the coal body itself can not only bring the tensile damage crack formation is more clear,and by comparing the two groups of test model X-Z and X-Y section profile can see the former blasting hole to control hole fractured well.It pointed out that the deep hole pre splitting blasting into the coal seam floor can ensure that the fracture area reaches at least 4m.In the process of similar simulation,through the observation of the surface of the two sets of models,it is found that the blasting hole will form a funnel shaped hole which is spreading to the surrounding.This phenomenon is particularly evident in a group of "floor" blasting will crack density,also by blasting hole center to control hole hole blasting hole can be extended to make change,and the formation of crater is more typical,the crater diameter is more than 3 times the diameter of 41mm with the blasting hole ?12mm.According to the comparison of the test area of deep hole presplitting blasting gas in Gaocheng Coal Mine 25091 sub lane(North)of Zhengzhou Coal Group,the drainaging gas recovery and extraction concentration and extraction of pure flow could be seen that the maximum of the gas extraction concentration and pure quantity was 10.23 and 6.92 times than before after the deep hole pre-splitting blasting.And the results show that the radius of influence of single hole blasting crack is 4.5m effective and reliable,and the gas flow rate and the amount of pure gas were greatly reduced,and the effect of extraction has been improved. |
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