极近距离煤层开采下位巷道破坏特征及控制研究

Research on Failure Characteristics and Control Methods of Lower Roadway in Ultra-close Distance Coal Seams

极近距离煤层群开采下位巷道受上煤层采动影响变形严重维护困难。以六家煤矿E_(I)N_(4)段6-7运输顺槽为工程背景,研究采空区下拱形巷道的变形破坏特征。钻孔窥视表明,E_(I)N_(4)段6-7运输顺槽两帮的煤体整体性较好,顶板受到上部E_(I)N_(5)段6-5工作面回采的影响产生明显的破碎区。采用滑移线理论建立底板损伤范围力学模型,计算得到6-5煤层开采后底板损伤深度为14.18 m。数值模拟分析表明,E_(I)N_(4)段6-7运输顺槽浅部围岩形成应力释放区,顶板变形量大于两帮,巷道周围的破坏区域在顶部高度约3 m,肩角处深度2~2.5 m,两帮和底板的深度为1 m。提出“钢带锚网+注浆锚杆+注浆锚索”联合支护技术,现场应用后最大顶底板移近量为560 mm,最大两帮移近量为430 mm,有效控制巷道满足生产要求。

It is a difficult problem that the large deformations control of lower roadway affected by the mining of the upper coal seam in ultra-close distance coal seams mining.Based on the engineering background of the 6-7 headgate in the E_(1)N_(4)section of Liujia coal mine,the deformation and failure characteristics of the arched roadway under the goaf are studied.Drilling peek shows that the integrity of the coal in the 6-7 section of the E_(1)N_(4)section is good,and the roof is affected by the mining of the 6-5 working face of the upper E_(1)N_(5)section,resulting in an obvious broken area.Using the slip line theory to establish the mechanical model of the damage range of the floor,it is calculated that the damage depth of the floor after the mining of the 6-5 coal seam is 14.18 m.Numerical simulation analysis shows that the 6-7 headgate in E_(1)N_(4)section forms a stress release zone in the shallow surrounding rock,and the roof deformation is greater than the two sides.The damage area around the roadway is about 3 m high at the top,2~2.5 m deep at the shoulder corner and 1 m depth at the two ribs and floor.The joint support technology of"steel belt anchor net+grouting anchor rod+grouting anchor cable"is proposed.The maximum approach of the roof and floor used in the field is 560 mm,and the maximum approach of the two sides is 430 mm,which can effectively control the roadway to meet the production requirements.