注浆压力对顺层抽采钻孔封孔质量影响研究

Influence of grouting pressure on sealing quality of bedding extraction borehole

为研究不同注浆压力下各顺层钻孔的封孔质量,以轩岗煤电有限责任公司刘家梁煤矿2214工作面为试验对象,根据矿井煤层实际赋存情况,采用COMSOL数值模拟软件,模拟不同注浆压力下浆液在煤层中的扩散范围,数值模拟结果表明,在1~4 MPa注浆压力范围内,浆液在煤层中的扩散半径与其注浆压力的大小成正相关关系,而浆液扩散半径的增加幅度随注浆压力的增加呈现逐渐减小的变化趋势。同时在钻孔始封深度、封孔长度等封孔参数一定的情况下,按照1、2、3和4 MPa四个等级进行现场顺层钻孔封孔试验,并利用漏气率对各抽采钻孔的封孔质量进行评价和对比,现场试验表明,采用1 MPa和2 MPa注浆压力的顺层钻孔分别有4个和2个钻孔出现漏气,其平均漏气率分别为32.76%和28.65%,而采用3 MPa和4 MPa注浆压力的钻孔均未出现漏气现象。综合数值模拟及现场试验结果表明,该工作面顺层钻孔封孔时其注浆压力应不小于3 MPa。

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.