顶板高位定向钻孔瓦斯抽采技术及工程实践

High-level directional drilling gas drainage technology in roof and its engineering practice

针对大孔径定向钻孔稳定性较差而影响瓦斯抽采效果的问题,本文以陕西省大佛寺煤矿40103工作面为工程背景,首先采用FLAC^(3D)模拟研究了不同孔径下钻孔围岩应力、位移及塑性变形情况,并开展了等效应力护孔效果分析;其次对不同直径及内支撑护孔管开展了轴向抗压实验;最后通过高位定向钻孔现场实践,进一步验证选配孔径和层位对钻孔抽采效果的影响。研究结果表明:对于四种不同孔径(100 mm、130 mm、160 mm、200 mm)的顶板钻孔,随着孔径的增大,钻孔稳定性随之降低,周边岩体逐渐失稳发生变形,现场宜选择Φ160 mm钻孔。在模拟施加等效应力护孔后,钻孔围岩应力集中得到缓解,周边岩体位移和塑性破坏区也随之减小;与普通护孔管(无内支撑)相比,内支撑结构护孔管的抗压性能显著提高,一字形和十字形效果较好,十字形护孔管抗压强度是普通护孔管的4倍;现场施工Φ160 mm顶板高位定向钻孔取得了较好的抽采效果,工作面从切眼推采至315 m期间,冒落带(13~15 m)第一层位、冒落带(23~25 m)第二层位、裂隙带(33~36 m)第三层位抽采瓦斯流量分别为1.46~4.21 m^(3)/min、1.58~5.32 m^(3)/min、1.53~6.02 m^(3)/min。

This paper analyzes the stability of large-diameter directional drilling,using the 40103 working face of Dafosi Coal Mine in Shaanxi Province as the engineering background.FLAC^(3D) is used to simulate the stress,displacement,and plastic deformation of the surrounding rock under different diameters.The effect of equivalent stress drilling protection is also analyzed.Axial compression experiments are conducted on drilling protection pipes with varying diameters and internal supports.Additionally,the impact of selecting diameter and horizon on drilling drainage effect is further verified through field practice of high-level directional drilling.The research results indicate that as the size of roof drillings increases from as 100 mm,130 mm,160 mm,and 200 mm,drilling stability decreases and the surrounding rock mass gradually becomes unstable and deforms.Therefore,it is recommended to select aΦ160 mm drilling on site.After simulating equivalent stress to protect the drilling,the stress concentration in the surrounding rock of the drilling is relieved,and the displacement and plastic failure zone of the surrounding rock mass are also reduced.Compared to the common drilling protection pipe(without internal support),the drilling protection pipe with internal support structure significantly improves compressive performance.The effect of one-line and cross is better,and the compressive strength of the cross-drilling protection pipe is four times that of the common drilling protection pipe.The directional drilling drilling of theΦ160 mm has achieved effective drainage.During the mining process,from the cut to 315 m,the gas drainage flow rates are measured at the first horizon of the caving zone(13-15 m),the second horizon of the caving zone(23-25 m),and the third horizon of the fracture zone(33-36 m),the gas extraction flow rates are 1.46-4.21 m3/min,1.58-5.32 m3/min,and 1.53-6.02 m3/min,respectively.