蠕变-渗流耦合作用下不同埋深有效抽采半径研究

摘要

为了研究不同埋深有效抽采半径,建立了钻孔周围煤体黏弹塑性模型,研究了不同埋深钻孔孔径变化规律及有效抽采时间,建立了蠕变-渗流耦合作用下的瓦斯运移模型,确定了不同埋深钻孔的有效抽采半径.研究结果表明:深部煤层有效抽采半径受到煤体蠕变变形加剧、渗透率降低及瓦斯压力升高的综合作用;试验矿井埋深400及600 m煤体蠕变变形较为平缓,钻孔缩孔幅度有限,仍维持较好的抽采通道,所有抽采时间均为有效抽采时间,但是埋深800 m煤体蠕变变形愈加剧烈,钻孔缩孔速度快速增加,仅30 d就会堵塞抽采通道,其有效抽采时间仅为30 d;埋深400,600和800 m钻孔3个月的有效抽采半径分别为2.88,1.62和0.82 m,数值计算结果与现场实测相吻合,研究成果可为抽采钻孔的优化布置提供参考.%In order to study the effective gas extraction radius of different burial depths,the visco-elastic-plastic model of the surrounding coal was established,the aperture variation and effective extraction time of different burial depths were researched,the gas migration model under creep-seepage coupling was established,and the effective gas extraction radius of different burial depths were determined.The results show that the effective gas extraction radius of deep coal seam is affected by the creep deformation of coal body,the decrease of permeability and the increase of gas pressure.The coal deformation of 400 m and 600 m depth is more gentle,and the boreholes shrinkage range is relatively smaller,still maintain a good extraction channel,all extraction time are effective extraction time,but the coal creep deformation of 800 m depth is more intense,boreholes shrinkage rate increases rapidly,only 30 d will plug extraction channel,the effective extraction time is only 30 d.The effective gas extraction radius of 400 m,600 m and 800 m are respectively 2.88 m,1.62 m and 0.82 m,the numerical results are in agreement with the field observations.The research results can provide the reference for the optimal layout of boreholes.