| Gas has always been a major disaster faced by coal mines for safe production,and it has caused the most serious human and economic losses.Analyzing the development law of cracks in the overlying strata of coal seams and proposing targeted gas drainage schemes can provide active safety guarantees for coal mine safety production.In view of the lack of quantitative research on the compressed gas enrichment area at this stage,this paper uses theoretical analysis,laboratory physical similarity simulation,COMSOL multiphysics numerical simulation and field detector detection to accurately determine the high concentration gas enrichment area.The 2407 working face of Yuhua Coal Mine was verified by engineering tests.The thesis determined the crack area of the overburden rock caused by mining through physical similar simulation experiments,and studied the evolution law of the cracks in the 4-2 coal seam.It was concluded that the height of the caving zone was 24.6 m,the caving ratio was 4.1;the height of the fracture zone was 66.9m,and the fracture mining The ratio is 9.6;when the working face advances 34m,the first break(compression)of the basic roof occurs,the breaking angle of the roof is 44°,and the rotation angle of the basic roof is 16°;the working face advances to 54m,and the first cycle of compression occurs;During the process of working face advancement from 54m to 140m,a total of 5 late compressions occurred,and the periodic compression step is 17m.Put forward a new idea of dividing the gas flow process in the goaf into "high-level high-concentration gas flow horizontal enrichment circle" and "low-level low-concentration gas vertical rise and float horizontal flow circle",and establish a detection hole mining failure and overburden activity Regular inversion relationship;At the same time,Surfer software and AutoCAD software are used to determine that the gas enrichment area is within the range of working face inclination 10～45m,and the height is 5-8 times the mining height.Analysis of the gas drainage effect of the large-diameter drilling field,Verifying that the impact range of dynamic pressure relief is the post-harvest simulation result.During the entire working face recovery period,the total gas emission averaged 22.50m3/min,the average air exhaust gas volume was 8.12m3/min,the total extraction volume averaged 14.38m3/min,and the air exhaust gas volume accounted for 36.09%of the total emission.Gas drainage accounts for 63.91%of the total emission;the average gas drainage rate of the working face is 62.26%;the return air flow of the working face and the gas concentration between the frames are both below 0.3%,which ensures the safe and efficient mining of the working face and the efficient gas drainage Pick.Validation of the model and research method proposed in this paper shows that after analyzing the crack development law of the overlying strata of the coal seam,the gas enrichment area,and determining and optimizing the gas drainage plan,it can effectively solve the coal mining face with serious gas emission.The problem of over-limit angle gas is of great practical significance in the safety protection of underground workers,the control of the gas concentration at the upper corner of the working surface,the suppression of gas emission in the goaf,and the saving of gas drainage costs. |
