| This paper aims at the problems of poor coal permeability,difficulty in gas drainage,and poor outburst prevention effect in the 2125 lower tunnel driving face of Hemei No.6 Mine,which lead to the slow progress of the driving face.A combination of numerical simulation and field test is used to test the coal roadway.The effectiveness of outburst prevention measures for loose blasting in driving face was investigated,and the effective influence radius of loose blasting was obtained through field test methods,and then the loose blast prevention measures for outburst prevention of loose blasting in the 2125 lower channel driving face of Hemei No.6 Mine were optimized.And the optimized loose blasting anti-outburst measures were investigated,and the following main researches were obtained:(1)Through the numerical simulation of single hole blasting,single control hole blasting,and double blast hole blasting,the blasting effect of the front view and the top view is analyzed and compared,and it is concluded that the blast hole is coupled with the charge when the blast hole diameter is 42 mm and the control hole diameter is 80 mm.The distance between the control hole and the blast hole is 3m,and when the blast hole distance is 6m,it is the best blast hole spacing;the loose blasting test was carried out at 16m and 24m of the tunnel driving face under 2125.Comparing the coal seam gas content before and after the loose blasting test,it can be seen that the coal seam gas content before blasting was 5.64 and5.86 m~3/t,and after blasting it was 5.07 and 4.79 m~3/t;the effect inspection index q value of the test area before the test test was 3.86 and 3.67 L/min,respectively.The q values after blasting were 3.28 and 3.10L/min.The inspection indexes and gas content of the anti-outburst measures have been significantly reduced.The comprehensive simulation results and the actual measurement results have proved the effectiveness of the loose blasting anti-outburst measures on the 2125 working face.(2)Through the analysis of the data change of the gas drainage concentration before and after the loose blasting of the two sets of test holes,the effective influence radius of the loose blasting of the 2125 working face is 4.0-4.2m.Based on this,the effective radius of loosening blasting is determined to be 4.0m;according to the measurement result of the effective influence radius of the loosening blasting measures,the drilling hole is 4.0m,that is,R is equal to 4.0m,and the spacing between the bottom of the blasting hole and the bottom of the control hole is optimized to not exceed√2.The technical scheme of loose blasting anti-outburst measures is divided into two types of layouts,single-row holes and double-row holes according to coal thickness.(3)Through the investigation of the effect of loose blasting prevention measures,the measured coal seam gas content before blasting is between 4.89～5.92m~3/t,after blasting the measured coal seam gas content is between 4.68～5.16m~3/t,the gas content is significantly reduced;When the loose blasting measures are implemented,the outburst prevention effect inspection index q value will be reduced;After the implementation of loose blasting measures,the amount of gas emission from the 2125 tunnel driving face will increase significantly,and will gradually decrease to the original level after 4 hours.This is due to the cracks generated by the blasting and the increase in the permeability coefficient of the coal before the work the reason.;after the implementation of loose blasting measures,the monthly footage of the experimental tunneling face was increased from the original 25m to 84m,an increase of 2.36times,normal circulation was achieved,and coal prevention and control were achieved.Gas outburst,the purpose of rapid excavation of coal roads.There are 73 pictures,11 tables and 62 references in this paper. |
