近距离煤层群半煤岩上保护层开采卸压增透效应研究

Study on pressure relief and permeability enhancement effect of upper protective layer mining of semi-coal rock in close distance coal seam group

基于保护层开采是治理低渗透率高瓦斯突出煤层最有效措施,针对薄煤层和极薄煤层保护层的开采,提出了截割软弱底板以增加开采高度的半煤岩保护层工作面开采方法。以中兴煤矿3203保护层工作面为工程背景,通过滑移线场理论分析计算了3203上保护层工作面开采后底板岩体的最大破坏深度,并采用数值模拟方法对半煤岩上保护层开采卸压增透效应进行讨论。研究结果表明:3203保护层工作面开采后,底板岩体最大破坏深度h_(max)达20.74 m,底板最大破坏深度距离工作面煤壁的水平距离为13.99 m;3203被保护层的卸压率为0.58,在3203工作面对应区域膨胀变形率均大于6‰;残余瓦斯含量为4.57 m^(3)/t,可解吸瓦斯量W_(j)为0.68 m^(3)/t,煤层透气性系数由0.0437 m^(2)/(MPa^(2)·d)增加至1.08 m^(2)/(MPa^(2)·d),孔隙率由3.5%增加至4.05%,残余瓦斯压力为0.31 MPa,实现了高瓦斯矿井突出煤层高效、安全、经济生产的目的。

Based on the present situation that protective layer mining is the most effective measure to control low permeability and high gas outburst coal seam,aiming at the mining of protective layer in thin coal seam and extremely thin coal seam,the mining method of semi-coal rock protective layer working face with cutting soft floor to increase mining height is proposed.Taking the 3203 protective seam working face of Zhongxing Coal Mine as the engineering background,the _(max)imum failure depth of the floor rock mass after the mining of the 3203 protective seam working face was calculated by the slip line field theory,and the pressure relief and permeability enhancement effect of the mining of the upper protective seam of semi-coal rock was discussed by using the numerical simulation method.The results show that after the mining of 3203 protective seam working face,the _(max)imum failure depth h_(max) of floor rock mass reached 20.74 m,and the horizontal distance between the _(max)imum failure depth of floor and the coal wall of working face was 13.99 m.The pressure relief rate of 3203 protected layer reached 0.58,and the expansion deformation rate of 3203 working face was greater than 6‰.The residual gas content was 4.57 m^(3)/t,desorbable gas W_(j)=0.68 m^(3)/t,the permeability coefficient of coal seam increased from 0.0437 m^(2)/(MPa^(2)·d)to 1.08 m^(2)/(MPa^(2)·d),the porosity increased from 3.5%to 4.05%,and the residual gas pressure was 0.31 MPa.The purpose of efficient,safe and economic production of outburst coal seam in high gas mine was effectively realized.