倾斜煤层卸压瓦斯导流抽采技术研究与工程实践

Technology research and engineering practice of pressure-relief gas diversion extraction in inclined coal seams

为了研究倾斜煤层条件下,采动覆岩裂隙分布规律与卸压瓦斯抽采技术,采用理论分析和数值模拟的方法,对采场覆岩应力、位移以及裂隙分布情况进行了分析,并依据研究结果,对试验工作面高位导流钻孔布置参数进行了优化设计。结果表明:工作面上端头顶板卸压区域范围大于下端头区域,关键层的卸压段靠近工作面上部,覆岩垮落破断后,工作面上部垮落岩体位移明显大于下部;裂隙网络中,下部冒落岩体裂隙处于相对闭合状态,沿工作面向上,裂隙开度逐渐增大;卸压瓦斯运移通道在倾斜方向上具有不对称性;沿工作面回风巷侧冒落带轮廓线布置高位导流钻孔,并配合相邻钻场之间的有效搭接抽采可使抽采效果保持稳定;单一钻孔全生命周期可分为远距离、有效和近距离抽采3个阶段,随着钻孔层位的增加,抽采效果逐渐变优,远距离抽采阶段长度减小,有效抽采阶段长度增加。实践结果表明,瓦斯抽采效果良好,验证了依据此方法布置高位导流钻孔的合理性。

In order to study the fracture distribution law of mining overlying strata and the technology of pressure-relief gas drainage in inclined coal seams, the overburden stress, displacement and fracture distribution in the mining stope have been analyzed through theoretical analysis and numerical simulation, and the layout parameters of the high level boreholes of the test working face have been optimized based on the research results. The research results have shown that the range of the pressure relief area in the top plate on the working face is larger than that in the lower area, and the pressure relief section of the key layer is close to the upper part of the working face. After the overburden is broken, the displacement of the collapsed rock mass on the working face is significantly larger than that on the lower part. In the fracture network, the fracture of the lower falling rock mass is relatively closed, and the fracture opening gradually increases along the working plane. The pressure relief gas migration channel is asymmetric in the oblique direction. The layout of high diversion drillings along the contour line of caving zone on the side of the return airway of the working face, coupled with the effective overlap drainage between adjacent drilling sites can keep the drainage effect stable. The full life cycle of single borehole can be divided into three stages: long distance extraction, effective extraction, and short distance extraction. With the increase of the borehole horizon distance, the extraction effect gradually improves, the length of the long-distance extraction stage reduces, and the length of the effective extraction stage increases. The practical results show that the gas drainage effect is good, and the rationality of laying high level boreholes according to this method is verified.