弱透气性煤层受岩石下保护层开采影响卸压增透效果研究

针对平煤股份十矿大埋深弱透气性煤层下保护层开采工程，采用岩石破裂损伤理论和有限元计算方法，研究了被保护层变形规律、应力演化过程、卸压保护范围及瓦斯抽采效果。结果表明，随着保护层工作面的推进，其上覆煤岩体同时发生拉伸应力和剪应力破坏，被保护层大量的裂隙扩展发育，孔隙率大幅提高；随着保护层的开采，被保护层呈现出压缩和膨胀的变化规律，位于保护层采空区中部上方的被保护层变形最大，变形膨胀率最大，因此有利于煤层的卸压增透和瓦斯的抽放；岩石保护层开采后对被保护煤层沿倾斜方向预计保护范围卸压角为78°。工业试验显示:在己_15-16-24130岩石下保护层开采后，上覆己_15-16煤层变形膨胀率在0.62%~1.54%，己₁₇煤层变形膨胀率在1.71%~3.67%；在预计保护范围线位置测定的煤层最大综合残余瓦斯压力为0.42 MPa，最大残余瓦斯含量为4.210 7 m³/t。证明预计保护范围是可靠的，为平煤十矿下保护层开采区域瓦斯治理技术的推广应用提供了可靠的依据。

Study on pressure relief and permeability increasing effect with the coal seam of low permeability under influence of rock protective layer mining

Aiming at the mining project of protective seam under large buried depth and weak permeability coal seam in Pingdingshan No.10 Coal Mine.
The deformation law，stress evolution process，pressure relief protection range and gas drainage effect of the protected layer are studied by using rock fracture damage theory and finite element method.The analysis results showed that with the advance of the protective layer working face，both tensile stress and shear stress damage occur in the overlying coal and rock mass，a large number of cracks in the protective layer expand and develop，and the porosity increases greatly.With the exploitation of the protective layer，the protective layer presents the rule of compression and expansion.The protective layer located above the middle of the protective layer gob has the largest deformation and expansion rate，which is beneficial to pressure relief and permeability enhancement of coal seam and gas drainage.After mining，the pressure relief angle of the protected coal seam along the inclined direction is predicted to be 78 degrees.Field tests show that after mining of the protective layer under the rock of Ⅵ_15-16-24130，the swelling deformation of the overlying Ⅵ_15-16 coal seam is between 0.62% and 1.54%，and that of the Ⅵ₁₇ coal seam is between 1.71% and 3.67%.The maximum comprehensive residual gas pressure is 0.42 MPa and the maximum residual gas content is 4.210 7 m³/t measured at the position of the predicted protection range line.It proves that the predicted protection range is reliable and provides a reliable basis for the popularization and application of gas control technology in the mining area of the lower protective layer in Pingdingshan No.10 Coal Mine.