上覆坚硬厚顶板煤岩卸压增透数值模拟及应用研究

Numerical and application study on pressure relief and antireflection of overlying hard thick roof coal-rock

基于榆树田煤矿上保护层开采时被保护煤层上覆岩层为坚硬厚岩层的实际情况,采用物理实验、数值模拟和现场应用等方法,研究上保护层开采推进时被保护区域的应力变化尤其是垂直应力演化规律和原岩应力区、应力增高区和降低区的演化规律,继而设计保护层开采方案并选定高位定向长钻孔进行瓦斯抽采。结果表明,被保护层上覆的坚硬厚岩层会形成关键层直接影响保护层效果;上保护层开采后被保护层的卸压程度为50%,膨胀变形量为0.391%,被保护层工作面回风瓦斯浓度降低至0.35%。现场应用结果表明,被保护煤层上覆坚硬厚岩层时,采用上保护层开采配合高位定向长钻孔抽采能够取得理想的卸压增透和瓦斯抽采效果。

Based on the hard and thick overlying strata of the protected coal seam in Yushutian Coal Mine.Physical experiments,numerical simulation and field application were adopted to study on the stress characteristics of the protected area,especially the vertical stress evolution law of the protected coal seam,and the variation law of the original rock stress area,stress-concentrated area and the pressure relief area.The scheme of protective layer mining was therefore designed.The high directional long borehole was selected for gas drainage.The results showed that the key stratum will be formed in the hard and thick strata when the upper protective stratum is mined,which will directly affect the mining effect of the protective layer.After mining of the upper protective layer,the pressure relief intensity of the protected layer is 50%,the swelling deformation is 0.391%,and the concentration of air gas in the working face of the protected coal seam is reduce to 0.35%.The field application shows that when the protected coal seam is overlaid with hard and thick rock,the optimal effect of pressure relief,antireflection and gas extraction can be achieved by employing the upper protective layer mining and directional long borehole methods.