采场围岩应力壳对破坏场的影响规律及应用

为获得高瓦斯工作面采动应力场对煤岩破坏导致渗透性变化的影响规律,进而指导瓦斯抽采的工程应用,采用计算机数值模拟对长壁工作面围岩应力壳分布及对破坏场的影响进行了研究和分析,获得了采场围岩应力壳对破坏场的影响规律。研究表明:长壁工作面围岩应力壳是煤层和围岩的破坏和裂隙发育的主控因素,破坏和裂隙一般发育在应力壳高应力集中带下方的卸压区内,在应力壳高应力集中带及其上方岩层破坏和裂隙并不发育;受应力壳壳基的影响,工作面煤壁前方、回风巷下帮及运输巷上帮煤体的破坏发育区域均分布在壳基内侧的低应力区内;高瓦斯低透气性煤层距工作面煤壁15 m内破坏和裂隙发育,此区域渗透性强,应加强煤层顺层钻孔的抽采力度。高抽巷、地面钻井及穿层钻孔的布置均应考虑应力壳的形态和破坏场的发育,钻孔抽采位置宜选择在应力壳下低应力区内。

Numerical investigation on the influence of surrounding rock stress shell on fractured field

To investigate the influence of mining-induced stress on the breakage of coal and the change of permeability in high gas coal working face，a numerical simulation was conducted to deeply examine the relationship of stress shell distribution with failure field.The results indicate that the stress shell in long wall mining working face is the main cause for inducing the failure of coal and rock.Rock failure and newly-born fissures mostly occur in the stress releasing zone under the high stress concentrated area，while little evidence of new fissures development is shown in the places above the stress shell concentration zone，in addition，the coal failure areas，which are in front of coal wall at working face，in the down side call wall of return roadway and in the upside coal wall of haulage roadway，are distributed in low stress area inside the shell base.Failure and fissures mostly develop within 15 m from the coal wall of high gas and low permeability coal seam.Permeability is strong in this area，and the extraction of drill holes along coal seam should be strengthened in this area.The spatial distributional configuration and development of stress shell should be fully considered when surface drainage holes，gas drainage road and drainage holes along seam are laid out.The effect of gas drainage is the best when holes are drilled in low stress area where failure and cracks are well developed.