1. Beijing Key Laboratory for Precise Mining of Intergrown Energy and Resources,China University of Mining and Technology( Beijing),Beijing　 100083, China; 2. School of Mechanics and Civil Engineering,China University of Mining and Technology(Beijing),Beijing　 100083,China

为解决大采高采场及上隅角瓦斯超限问题,基于卸荷岩体力学分析了采高对采空区顶板卸荷及瓦斯通道损伤演化的影响,结合损伤力学建立了损伤因子与卸荷量及渗透率的关系,采用离散元软件计算了不同采高下采空区顶板卸荷及瓦斯通道损伤演化规律,根据卸荷后有效应力与渗透率关系研究了不同采高下瓦斯通道的卸荷损伤范围,提出利用大采高开采形成的优势瓦斯通道在中高位断裂带内采用大直径定向钻孔抽采采空区瓦斯,并验证了瓦斯通道的贯通发育。结果表明:采空区顶板卸荷程度随采高增大非线性增长;采高越大,采空区顶板卸荷量及损伤因子越大,裂隙发育数量越多,采空区顶板渗透率突变点及瓦斯通道发育的高度越大;应用153 mm大直径钻孔抽采流量为96 mm的2～3倍,中高位瓦斯通道区钻孔抽采浓度约为中低位的2. 4倍。

To solve the safety problems of gas’s concentration exceeding limits at the large mining height coal working face and its upper corner,the effect of mining height on roof unloading and gas flow channel damage evolution in goaf was analyzed based on the theories of unloading rock mass mechanics. Combining with damage mechanics,the relation- ships between damage factor,unloading percentage and permeability were built. And the roof unloading and gas flow channel damage evolution laws of goaf in different mining height working faces were calculated by the discrete element method. Meanwhile,the unloading damage scope of gas flow channel in different mining heights was analyzed according to the relationship between effective stress and permeability after unloading. Then it provided a gas drainage technology of directional boreholes with large diameter in the middle-high fracture zone by using favorable channel formed in large mining height mining,and it verified the cracks connect and development of gas flow channel. The results have shown that roof unloading degree increases nonlinearly with the increase of mining height;the larger the mining height,the greater unloading percentage and the damage factor of roof,the more generated fractures,then the position of roof per- meability catastrophe point and gas flow channel development are much higher. Drainage flow velocity using 153 mm diameter borehole is about 2-3 times more than that using 96 mm diameter,and the drainage concentration of bore- holes in the middle-high zone of gas flow channel is about 2. 4 times higher than that in middle-low zone.

国家重点研发计划资助项目(2016YFC0600708)；中央高校基本科研业务费专项资金资助项目(2011YZ05)；

XU Yusheng,LI Chunyuan, ZHANG Yong, et al. Unloading damage evolution and drainage verification of gas flow channel in different mining heights[ J]. Journal of China Coal Society,2018,43 (9):2501 -2509.