煤层群薄煤层机械化开采卸压增透机理研究

With the increase of the mining depth, the geostress, gas pressure and gas content have increased significantly. As a result, dynamic disasters such as rock burst and coal and gas outburst have become the main threats to detriment the normal mining process and have become the critical issues in the deep seams mining. This project takes the coal seam group mining as the object, with the adoption of theoretical analysis, numberical modeling and in-situ experiments, under the condition of different mining method( longwall mining and drilling mining), different mining depths and working face length，research on the delivery law of methane, reliving area and distribution of fractured in protective seam and being protected seam are carried out when mining the protective seam. Stress-Damage-Flow coupling model of surrounding rock induced by the mining effect is established. With different mining method and different distance and lithological characters between protective seam and protected seam taken into account, surrounding rock stress, time-space evolution law of factures and critical mining height and its calculation method can be reached. This project can provide reasonable selection of mining method and parameters of working face and to establish the relief mining system of thin coal seam group with high pressure and high methane, to promote the safty mining in deep coal seam group with high gas.

随着矿井开采深度的增加，地应力、瓦斯压力和含量显著增加，开采受冲击地压和煤与瓦斯突出等动力灾害威胁的可能性增加，成为深部煤层群开采亟待解决的难题。项目以煤层群开采为研究对象，采用理论分析、数值模拟及现场工业性试验等研究手段，研究不同薄煤层开采方式（长壁式及钻式开采）、开采厚度及工作面长度条件下，保护层开采引起的本层和被保护层围岩应力、裂隙分布、卸压范围和瓦斯运移规律，建立受采动作用的围岩应力-损伤-渗流耦合模型。研究不同层间距、层间岩性及开采方式下，薄煤层保护层开采造成的围岩应力、裂隙时空演化规律以及薄煤层保护层开采临界卸压采厚，提出临界卸压采厚计算方法。为不同条件下保护层及被保护层开采方法选择及工作面回采参数确定提供指导，建立高应力及高瓦斯煤层群薄煤层卸压开采理论体系，促进高瓦斯深部煤层群的安全高效开采。

随着矿井开采深度的增加，地应力、瓦斯压力和含量显著增加，开采受冲击地压和煤与瓦斯突出等动力灾害威胁的可能性增加，成为深部煤层群开采亟待解决的难题。卸压开采结合瓦斯抽采是实现高瓦斯煤层群煤与瓦斯共采的有效方法。而应力-裂隙-渗流耦合作用机理是高瓦斯煤层群卸压开采的基础问题，直接影响着卸压开采的成败和效果。为此，本项目采用理论分析、实验室实验、数值模拟以及现场实测相结合的方法开展了以下研究：①研制了采动煤岩体渗透测试实验系统，实现了煤体轴向和径向渗透率的测试。提出了覆岩“三带”损伤裂隙煤岩体试样分类及制备方法，测试了不同损伤煤岩体渗透率随工作面开采及瓦斯抽采的时空演化规律，建立了重复采动作用下煤岩体应力-渗透率模型，评价了损伤煤岩样的应力敏感性及其演化特征。②构建了不同裂隙结构煤体渗透率的离散元数值模型，提出了节理裂隙数值模拟参数的标定方法，研究了煤体渗透特性的各向同性和各向异性特征，揭示了煤体损伤裂隙对渗透率应力敏感性的内在影响机理；掌握了裂隙形态及参数与裂隙煤样渗透率的内在联系。阐明了偏应力条件下采动裂隙煤样轴向渗透率对围压及轴压敏感性差异的主要原因。③建立了重复采动覆岩应力-损伤-渗流耦合模型，实现了煤层群卸压开采覆岩渗流特征的定量分析；确定了韩城矿区及淮南矿区上、下保护层开采的最小采厚及合理采厚，阐明了层间距与保护层采高的相关关系；设计了卸压瓦斯抽采钻孔布置方案。④建立了瓦斯分源模型，提出了卸压开采效果评价方法；定量分析了采空区垮落带各区域的压实时间、压实程度及渗透率分布特征，掌握了卸压开采围岩渗透率的时空演化规律。