Classification And Numerical Simulation Of Gas Drainage Technology In Pingshan Mining Area Based On I-FAHP-EWMDA

With the increase of coal mining depth,the mine gas content gradually increases,and the number of high gas outburst mines increases gradually.Gas control has become the primary problem to ensure the safety of mine production.However,the different gas drainage technology determines the different drainage effect and applicable conditions,and the classification of gas drainage technology is one of the important measures to improve the effect of gas control.In this thesis,combined with theoretical analysis,numerical simulation and field test methods,the evolution process of overlying rock fractures and gas migration characteristics,gas enrichment area,applicability of gas drainage technology,drainage technology classification,drainage combination mode and drainage effect are studied,and field experimental data are analyzed.Based on the F15.16-24130 working face in No.10 coal mine of Pingdingshan coal mine as the research background,with the help of FLAC3D and 3DEC numerical simulation software,the migration and failure law of overburden in coal seam group mining was studied,and the evolution process of stope fracture and gas migration law are revealed.The height of caving zone and fracture zone in stope is determined by analyzing the test data of overburden displacement change under different pushing progress.The development of overlying rock fracture presents "trapezoidal" state and moves forward with the advance of working face.According to the gas drainage technology method and selection principle,the typical gas drainage technology and applicable conditions in Pingdingshan mining area were analyzed.The relevant data of 16 coal mining faces in 12 mines in Pingdingshan mining area were investigated and collected,and 13 kinds of commonly used gas drainage technologies were selected.According to the gas source,it is defined as upper,middle and lower gas.According to the characteristics of coal and gas outburst in Pingdingshan mining area,the influencing factors are analyzed,the outburst risk evaluation index system were established,and the outburst risk level was divided.Combining with fuzzy comprehensive evaluation theory,the index function was introduced,and the "AHP" method and "EWM" method were improved by combining the dynamic adjustment coefficient.The I-FAHP-EWMDA evaluation model is proposed,and the coal and gas outburst of 16 working faces are analyzed by the model.The predicted results are in good agreement with the actual situation.The applicability evaluation index system of gas drainage technology is established.The applicability of 13 selected gas drainage technologies was evaluated by I-FAHP-EWMDA evaluation model.The evaluation results are analyzed and optimized.The gas drainage technology is classified according to the gas source position and extraction time,and the gas drainage technology mode is combined according to the classification results,and the three position linkage whole process gas drainage is proposed technology.With COMSOL Multiphysics numerical simulation software is used to establish the mathematical model of gas drainage.The gas drainage effect of different combination modes of drainage technology is studied by numerical simulation.According to the simulation results,the drainage effect of buried pipe in goaf,high-level borehole,bedding borehole of working face and floor crossing borehole of middle roadway and their combination modes are compared and analyzed.The results show that the combined mode of drainage technology can significantly improve the gas drainage effect to improve the gas drainage effect.According to the classification results of gas drainage technology,combined with the simulation results of gas drainage combined mode,the field experiment was carried out on the F15.16-24130 working face of No.10 coal mine of Pingdingshan coal mine.The gas drainage technology of three position linkage was analyzed from the aspects of residual gas content,residual gas pressure,drilling cuttings quantity,initial gas emission speed of borehole,gas drainage rate and gas concentration in return air roadway the results are as follows.The results show that the maximum residual gas content is 5.89m3/t,the maximum residual gas pressure is 0.548 MPa,the maximum drilling cuttings amount is 3.76 kg/m,and the maximum initial gas emission velocity is 2.59L/min.The results show that the gas drainage rate is 73.91%,and the maximum gas concentration in the return air roadway is 0.43%during the whole mining period,and the gas volume in the return air roadway is also reduced by 59.02%.