瓦斯抽采顺层钻孔封孔参数数值计算分析

Numerical Calculation and Analysis of Hole Sealing Parameters of Gas Drainage in Bedding

针对顺层钻孔封孔参数选择不当引起的钻孔瓦斯抽采效率低、瓦斯治理效果差的问题,采用FLAC3D软件模拟研究了顺层抽采钻孔封孔区域周围煤体应力-弹塑性形变演化规律,分析了钻孔周围煤体裂隙发育的影响因素,确定了钻孔封孔最佳参数。研究结果表明:钻孔周围裂隙发育情况与塑性区范围大小成正相关,封孔显著改变钻孔周围煤体应力场分布,塑性区范围明显减少,在巷道周围煤体原岩应力区与集中应力区的分界处进行封孔能有效支撑钻孔周围煤体,承载部分集中应力,降低应力集中系数,减小塑性区范围。该封孔参数优化方法用于东于煤矿顺层钻孔封孔后,应力集中系数降低54.6%,塑性区范围由0.32 m减小至0.13m,瓦斯抽采纯量提高了31.1%,抽采效果显著。

Aiming at the problems of low gas drainage efficiency and poor gas control effect caused by improper selection of hole sealing parameters of bedding boreholes,FLAC3D software was used to simulate and study the evolution law of stress elastic plastic deformation of coal body around the sealing area of borehole.Then the influencing factors of coal body crack development around the borehole were analyzed,and the optimal sealing parameters were determined.The results show that:the development of fractures around the borehole is positively correlated with the size of the plastic zone.Sealing borehole significantly changes the distribution of the stress field around the borehole,and the plastic area is significantly reduced.Sealing the hole at the boundary between the original rock stress area and the concentrated stress area of the coal body around the roadway can effectively support the coal body around the borehole,carry part of the concentrated stress,reduce the stress concentration coefficient and reduce the range of plastic zone.The optimization method of sealing parameters was used in Dongyu coal mine.After sealing the hole along the seam,the stress concentration coefficient was reduced by 54.6%,the range of plastic zone was reduced from 0.32 mto 0.13 m,and the pure gas drainage volume was increased by 31.1%,with a significant drainage effect.