Influence of grouting pressure on sealing quality of bedding extraction borehole
In order to study the sealing quality of each bedding borehole under different grouting pressure,the 2214 working face of Liujialiang Coal Mine of Xuangang Coal Power Co.,Ltd.was taken as the test object.Firstly,according to the actual occurrence of the coal seam,COMSOL software was used to simulate the slurry diffusion range in the coal seam under different grouting pressures,the results show that under 1～4 MPa grouting pressure,the diffusion radius of slurry in coal seam is positively correlated with the grouting pressure,and the increase of slurry diffusion radius decreases with the increase of grouting pressure.Secondly,with the constant sealing parameters such as the initial sealing depth and sealing length of the borehole,the on-site borehole sealing was tested according to the four grades of 1,2,3 and 4 MPa,and the sealing quality of each extraction borehole was evaluated and compared according to the air leakage rate.The field test shows that,there are 4 and 2 leaking holes with 1 MPa and 2 MPa grouting pressure,and the average air leakage rate is 32.76% and 28.65%,respectively,while there is no air leakage in the drill holes with 3 MPa and 4 MPa grouting pressure.The numerical simulation and on-site test results indicate that,the grouting pressure should be no less than 3 MPa in the bedding borehole sealing.
grouting pressurebedding gas extractionair leakage ratesealing qualityextraction borehole
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