坚硬岩层顶板切顶留巷关键参数确定与应用研究

Study on determination and application of key parameters of gob-side entry retaining by hard stratum roof cutting

以云盖山一矿22204工作面切顶留巷为工程背景,对直接顶内含有厚层较坚硬砂岩的预裂爆破切顶关键参数的确定进行了研究;建立了双孔爆破力学模型,采用CDEM数值模拟对比分析了不同切顶高度、切顶角度方案下留巷围岩的变形特征。结果表明:切顶可以有效减小留巷顶板悬臂长度,实现卸压保护巷道的目的;切顶高度的变化主要影响采空区的充填程度及短悬臂梁的厚度,切顶角度的变化主要影响顶板悬臂梁的长度以及矸石对悬臂梁的侧向支撑作用,切顶高度和切顶角度都存在1个合理的取值范围,并非越大越好;最终确定的切顶高度为9m,切顶角度为15°,爆破钻孔间距为800 mm,实现了成功留巷。

Taking the gob-side entry retaining by roof cutting(GERRC) of working face 22204 of No.1 coal mine of Yungaishan as the engineering background,the determination of key parameters of pre-splitting blasting roof cutting with thick and hard sandstone in the direct roof was studied.The mechanical model of double hole blasting was established,by simulation calculation with CDEM software,a numerical model was established to compare and analyze the deformation characteristics of surrounding rock in the roadway under the schemes of different heights and angles of roof cutting.The results show that roof cutting can effectively reduce the cantilever length of the reserved roadway roof and realize the purpose of pressure relief and roadway protection,and the change of cutting height mainly affects the filling degree of goaf and the thickness of short cantilever beam,and the change of the cutting angle mainly affects the length of the cantilever beam of the roof and the lateral support effect of the gangue on the cantilever beam.There is a reasonable range for the cutting height and cutting angle,which is not the greater the better.Final,the roof cutting height of about 9 m,the roof cutting angle of 15°,and the hole spacing between roof cutting holes of800 mm were obtained,which was applied in the field successfully.It has important guiding significance and engineering reference value for the application of roof cutting and roadway retaining technology under similar conditions.