The characterisations of Tectonically deformed coals (TDCs) are different from those of undeformed coals. Permeability characteristics of TDC and its influence factors should be studied deeply. In this paper, five samples of TDCs in various degrees of deformation and one undeformed coal were selected. The microstructure was observed by using scanning electron microscope. The pore structure characteristics were analyzed through a mercury injection experiment. Permeability was tested by steady flow. In TDCs, the crumpled and cracked microstructures are well developed and the mesopores and macropores account for large proportions. The permeability of TDC is mainly controlled by structural deformation degree, effective stress (or effective confining pressure), adsorption swelling effect and slippage effect. On the premise of only effective stress increasing, the internal space of deformed coal is compressed and the slippage effect is weakened. The both factors contribute to the permeability reducing in an exponential form. On the premise of only pore pressure increasing, the gas seepage channels are narrowed and obstructed because of the adsorption swelling effect and the slippage effect is also weakened. In this case, the permeability will also be reduced. In TDCs, the pores and fractures are strongly developed, the gas seepage channels are markedly unobstructed and the slippage effect is enhanced. Thus, the permeability of TDC is much larger than that of undeformed coal. Generally, the permeability change rate of TDCs is larger than that of undeformed coal and shows a negative correlation with effective confining pressure. The stress sensitivity coefficient of permeability also shows a negative correlation to the deformation degree of coals.

构造变形煤（TDCs）的特征与未变形煤的特征不同。应深入研究TDC的渗透特性及其影响因素。本文选择了5个不同变形程度的TDC样品和1个未变形的煤。通过使用扫描电子显微镜观察微观结构。通过水银注入实验分析了孔结构特征。通过稳定流动测试渗透率。在TDC中，皱缩和裂纹的微观结构非常发达，中孔和大孔占很大比例。TDC的渗透性主要受结构变形程度，有效应力（或有效围压），吸附溶胀作用和滑移作用控制。仅在有效应力增加的前提下，变形煤的内部空间被压缩，滑动作用减弱。这两个因素均导致指数形式的渗透率降低。在仅增加孔隙压力的前提下，由于吸附溶胀作用，气体渗流通道变窄而受阻，滑移作用也减弱。在这种情况下，磁导率也会降低。在TDC中，孔隙和裂缝强烈发育，气体渗漏通道明显畅通，滑移效果得到增强。因此，TDC的渗透率远大于未变形煤的渗透率。通常，TDCs的渗透率变化率要大于未变形煤的渗透率变化率，并且与有效围压呈负相关。