非爆破密集钻孔切顶机理及参数优化研究

Study on the Mechanism and Parameter Optimization of Non-Blasting Intensive Drilling Roof Cutting

预裂切顶是维护沿空留巷巷道围岩稳定性的一种重要方式,为了解决瓦斯聚集区域爆破切顶的安全性和采动裂隙发育区水力压裂的局限性问题,研究了沿空留巷切顶和未切顶时顶板力学结构、非爆破密集钻孔切顶机理及切顶钻孔的参数优化。基于钻孔周围应力集中致裂围岩的方法,分析了密集钻孔切顶的机理,运用数值模拟软件3DEC研究了密集钻孔对东峰煤矿3202进风顺槽沿空留巷复用巷道切顶的效果,并进行了参数优化。研究结果表明:在不进行钻孔切顶时,留巷顶板下沉严重;当钻孔直径为110 mm、间距为150 mm时,可形成密集钻孔弱化带,钻孔间岩层破裂明显;当钻孔高度为22 m、钻孔角度为仰角80°时,基本顶岩层完全垮落,留巷顶底板移近量明显减小。

Pre-splitting and roof cutting is an important way to maintain the stability of surrounding rock in gob-side entry retaining.In order to solve the safety of blasting and roof cutting in gas accumulation areas and the limitations of hydraulic fracturing in mining fracture development areas,the mechanical structure of the roof,the mechanism of non-blasting intensive drilling and roof cutting,and the parameter optimization of roof cutting drilling were studied under roof cutting and non roof cutting in gob-side entry retaining.Based on the method of stress concentration induced fracturing of surrounding rock around boreholes,the mechanism of roof cutting by intensive drilling was analyzed,and the effect of intensive drilling on the roof cutting of the reused roadway in gob-side entry retaining in the 3202 inlet airway of Dongfeng Coal Mine was studied by numerical simulation software 3DEC,and parameters optimization was carried out.The research results indicate that without drilling roof cutting,the roof of gob-side entry retaining sinks severely.When the diameter of the borehole is l10 mm and the spacing is 150 mm,a intensive weakening zone of the boreholes can be formed,and the rock stratum between the boreholes are significantly fractured.When the drilling height is 22 m and the drilling angle is 80°,the basic roof rock stratum completely collapses,and the displacement of the roof and floor of the gob-side entry retaining is significantly reduced.