缓倾斜煤层留窄煤柱切顶卸压合理参数研究

Study on Reasonable Parameters of Roof Cutting and Pressure Relief in Gently Inclined Coal Seam with Narrow Coal Pillar

为解决缓倾斜煤层留窄煤柱沿空掘巷巷道围岩变形较大的问题,以青云煤矿020203工作面为背景,通过建立缓倾斜煤层留窄煤柱切顶卸压沿空掘巷力学模型,计算出切顶角度应不小于-1.3°,切顶高度应不小于9.51 m。采用FLAC3D数值模拟软件模拟了留8 m窄煤柱时,不同切顶高度和切顶角度条件下巷道围岩应力及变形破坏规律。结果表明:切顶高度为10 m、切顶角度为0°时,基本顶能够完全切落,窄煤柱受力较小且均匀,围岩控制效果最好。现场试验表明,爆破钻孔间距为600 mm时,钻孔内部裂隙较多,孔壁破碎程度高,爆破效果理想;采用切顶卸压技术后,较不切顶区域020205轨道顺槽围岩变形量显著降低,说明切顶卸压有利于提高缓倾斜煤层沿空掘巷围岩稳定性。

In order to solve the problem of large deformation of surrounding rocks in gob-side entry driving with narrow coal pillars in gently inclined coal seam,based on the 020203working face in Qingyun Coal Mine,the mechanical model of roof cutting and pressure relief in gob-side entry driving with narrow coal pillar in gently inclined coal seam was established.It is calculated that the roof cutting angle should not be less than-1.3°and the roof cutting height should not be less than 9.51m.FLAC3Dnumerical simulation software was used to simulate the stress and deformation failure law of surrounding rocks in the roadway with different roof cutting heights and different roof cutting angles under leaving a narrow coal pillar of 8m.The results show that when the roof cutting height is 10mand the roof cutting angle is 0°,the basic roof can be completely cut off,the stress of narrow coal pillar is small and uniform and the control effect of surrounding rocks is the best.The field test shows that there are many cracks in the borehole,the degree of fragmentation of the borehole wall is high,and the blasting effect is ideal when the spacing of blasting boreholes is 600mm.After adopting the roof cutting and pressure relief technology,the deformation of surrounding rocks of the 020205track crossheading has been significantly reduced compared to that in the area without roof cutting,which indicates that roof cutting and pressure relief is beneficial to improve the stability of surrounding rocks in gob-side entry driving in gently inclined coal seam.