煤巷底板防冲钻孔释能解危原理及参数优化

Danger-relief principle and parameter optimization of borehole energy relief for rock burst in coal road floor

我国西北的华亭与彬长等矿区受水平构造应力影响严重,底板冲击地压显现剧烈。卸压钻孔是我国应用最为广泛的冲击地压防治解危措施,其具有解危效果良好、方便安全等特点,科学合理地制定卸压钻孔参数可有效提高防冲效率,但目前针对底板卸压钻孔的研究还相对匮乏。为此,基于底板破坏的力学模型,研究了底板钻孔的释能解危原理,建立FLAC^(3D)数值模型研究了不同钻孔参数的合理取值范围,并进行现场工业性应用论证。研究结果表明:①卸压钻孔可为底板弹性能缓慢释放提供自由空间,组成的“梯形”结构使煤层底板集中水平应力向深部岩层转移,破坏底板的蓄能条件,有效释放底板中的弹性能。②底板中的水平应力降低程度与钻孔倾角近似呈正相关,实施底板卸压钻孔倾角控制在60°~75°,可以取得较好的底板卸压解危效果;钻孔间距的合理取值范围在1~3 m,对整个底板的冲击地压防控可以起到理想效果;随着钻孔直径的增大,底板中心区域的应力降低程度随之增大,现场实施钻孔直径应在140~200 mm;理想钻孔排距布置应为1.4~1.8 m,并非越小越优。③研究成果应用于彬长矿区某矿,并对煤层底板防冲效能进行验证,其有效控制了底鼓程度和冲击危险强度,验证了底板解危防冲措施的有效性和钻孔参数的合理性。

The mine area located in northwest of China is seriously affected by horizontal tectonic stress.The borehole is widely used to control coal burst and is an effective,convenient and safe measure.The scientific and rational formulation of borehole parameters can effectively improve the efficiency of coal burst hazard prevention and controlling,but at present there is still a relatively lack of pertinent research.For this reason,based on the mechanical model of floor failure,this paper studies the principle of energy release and relief of floor drilling,establishes a FLAC^(3D)numerical model to study the reasonable value ranges of different drilling parameters,and conducts on-site industrial application demonstration.Research results show that:①It’s an effective measure to prevent the floor coal burst by releasing elastic deformation energy accumulated in coal and its energy storage condition and the“lader”structure transfer horizontal stress to deep strata.②The degree of horizontal stress reduction in the bottom plate is approximately positively correlated with the inclination of the borehole.Implementing the bottom plate pressure relief drilling angle of 60°-75°can achieve a better bottom plate pressure relief effect;The reasonable range of drilling spacing is between 1-3 m,which can have an ideal effect on the prevention and control of impact ground pressure on the entire bottom plate;As the diameter of the hole increases,the degree of stress reduction in the central area of the bottom plate increases,and the diameter of the drill hole implemented on site should be 140-200 mm;The ideal drilling row spacing arrangement should be 1.4-1.8 m,not the smaller the better.③The research results were applied to a mine in Binchang mining area,and the anti-scouring efficiency of coal seam floor was verified,it effectively controls the degree of the kick drum and the intensity of the impact hazard,the effectiveness of the measures to relieve the danger and the erosion of the bottom plate and the rationality of the drilling parameters are verified.