| At present,the proportion of hard coal seams in the proven coal reserves is about 43 %.It can be seen that the reserves of hard coal seams in China are very large.It brings many problems,such as : large pick loss,low efficiency of coal cutting,high dust concentration,serious spalling,prone to rock burst and other disaster problems.The above problems have seriously affected the production efficiency of coal mining enterprises,the underground green environment and the safety and health of miners.Therefore,in view of the safe,efficient and green mining of hard coal seam roadway,the integrated prevention and control of dust,spalling and rock burst is an urgent problem to be solved.Based on the background of a coal mine in Ordos,Inner Mongolia,he application of chelating wet coal seam water injection in hard coal seam tunneling is studied by combining theoretical analysis,mechanical experiment,numerical simulation,field engineering practice and field monitoring analysis.The main controlling factors of the three disasters and the shortcomings of the current traditional prevention and control are analyzed,and the mechanism of coal seam water injection disaster prevention is studied to provide a feasible basis for coal seam water injection.The numerical simulation method is used to study the law of coal seam water injection as a reference.The design uses the addition of chelating wetting agent to lag the head-on advanced water injection and the head-on rear advanced water injection scheme to solve the above problems in the field test,and verify the integrated disaster prevention effect of coal seam water injection from multiple angles.Through the analysis of online stress data,it can be seen that water injection can achieve a certain pressure relief effect on the hard coal wall within the effective wetting range,and it can be seen that the effective wetting radius increases after adding the chelating wetting agent.In the process of water injection,there are phenomena such as coal wall,bolt and floor seepage.According to the existing water injection flow,the water injection speed of adding chelating wetting agent is better than that of clear water.The drilling cuttings method is used to detect the risk of rock burst every 10 m at 1750-1850 of 804 glue transport crossheading in this coal mine,and the amount of drilling cuttings on the left and right sides is lower than the critical value.By analyzing the right side of water injection,it can be seen that the amount of drilling cuttings at 1750 places without water injection is too large,and the maximum value is 2.7kg,which is basically higher than the position after water injection in front and difficult to drill.By using the cross point method to monitor the displacement of the roadway and the displacement of the roof and floor in the west wing return air measures,the deformation of the roadway in the water injection section and the non water injection section is compared,and the water injection has a good effect on the roadway forming.According to the feedback of the field excavation team,the phenomenon of coal shot spalling in the water injection section is obviously reduced;by analyzing the dust amount data in the tunneling process and comparing the dust amount during the excavation of the non-water injection section and the water injection section,it can be seen that the dust amount is greatly reduced when the coal in the water injection section is excavated.It can be seen that the chelating wetting agent in the 804 glue transport roadway greatly reduces the dust generation during the excavation process,and the dust reduction effect is significant.The excavation progress is not affected in the coal seam water injection stage.From the perspective of theoretical analysis,numerical simulation and field control effect,coal seam water injection can realize the integrated prevention and control of dust,rib spalling and rock burst in hard coal seam tunneling roadway without affecting the tunneling progress. |
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