重复采动下近距离老空区破裂煤柱自燃机制研究

There are many coal pillars in the gob during exploiting in close distance coal seams. The coal pillar in the upper gob is fractured by multiple mining, which leads to the formation of air leakage passage in the fractured coal pillar. As a result, the coal pillar in the upper gob spontaneously ignites, which seriously threats the mine safety production. However, the mechanism of the spontaneous combustion of the fractured coal pillar in the close distance gob by multiple mining is not clear. Therefore, the theoretical analysis, experimental measurement and numerical simulation are employed to study the unclear mechanism. Firstly, the mechanical path of coal pillar (mining path for short) in the gob is analyzed through theoretical analysis and numerical simulation. The CT scanning experiment is conducted to study the strain and the fracture evolution of coal pillar in the mining path. Then the characterizing method between fractures and macroscopical deformation is established for expounding the law of fracture evolution of the coal pillar. Secondly, the seepage experiment in the mining path is employed to obtain the seepage law in fractured coal pillar and establish the permeability model of the fractured coal pillar. Then, the mechanism of the dynamic formation of the air leak path in the coal pillar is confirmed. Thirdly, thermo-hydro-mechanical temperature programmed experiment of coal pillar in mining path is carried out. The oxidation character of fractured coal pillar in different mining stress stages is study to distinguish the occurrence and development of coal pillar oxidation and spontaneous combustion. As a result, the mechanism of the spontaneous combustion of fractured coal pillar in close distance gob by multiple mining is acquired through conducting the project, which is important for gob spontaneous combustion control and prevention and the mining safety in close distance coal seams in theory and practice.

在近距离煤层群开采过程中，采空区内留有大量的保护煤柱。上覆老空区煤柱受重复采动作用产生破裂，形成漏风通道，诱发煤柱自燃，威胁矿井安全生产。然而重复采动下近距离老空区破裂煤柱自燃机制尚未清楚，因此本项目拟采用理论分析、实验测试、数值模拟相结合的方法，首先分析重复采动过程煤柱的力学路径（简称采动路径），开展采动路径下的煤柱裂隙演化CT扫描实验，研究应变、裂隙发育特征，建立裂隙与宏观变形间的表征方法，阐述煤柱破裂演化规律；其次，通过采动路径下的渗流实验，获得破裂煤柱的渗流规律，建立其渗透率演化模型，进而结合裂隙演化特征确定煤柱漏风通道动态形成机制。然后，开展采动路径下的热-流-固程序升温实验，研究破裂煤柱在不同采动应力阶段的氧化特征，识别其氧化自燃发生、发展过程。通过本项目的研究，获得重复采动下近距离老空区破裂煤柱自燃机制，这对近距离煤层群采空区自燃防治及安全开采具有重要的理论及现实意义。

在近距离煤层群开采过程中，采空区内留有大量的保护煤柱。上覆老空区煤柱受重复采动.作用产生破裂，形成漏风通道，诱发煤柱自燃，威胁矿井安全生产。通过项目的开展，确定了重复采动过程老空区煤柱的力学路径（简称采动路径），开展了采动路径下的煤样的力学实验和渗透率测试。通过实验和理论分析，建立了裂隙煤岩体渗透率各向异性演化模型，分析了开采过程中近距离煤层群老空区煤柱的破坏演化特征，获得了老空区煤柱漏风通道形成和自燃机制，这对近距离煤层群采空区自燃防治及安全开采具有重要的理论及现实意义。