深部低透气性煤层变形破坏的非连续大变形方法研究

瓦斯是引发煤矿重大灾害的主要因素，瓦斯抽采是防治瓦斯灾害的根本途径。我国50%以上的煤层具有低渗透、强吸附特征，瓦斯抽采极为困难。采取保护层开采和煤层密集钻孔等措施可有效增加煤层的透气性，提高瓦斯抽采率，但工程中存在凭经验作业、时效性差等问题，尚缺乏有效的科学理论指导。深部煤层增透作业中，煤岩体不仅发生非线性大变形，同时伴随着非连续的裂隙扩展与煤岩体破碎，目前缺少有效的理论描述方法和计算分析手段。本项目针对增透煤层非连续大变形的特点，试验研究低渗透性煤岩的大变形力学行为和破坏机理，建立煤岩体非线性大变形描述方法和力学本构方程，基于非线性变形分析，发展可以同时描述煤岩体大变形和非连续行为的理论和数值方法。结合工程实例，分析模拟煤层变形、裂隙扩展和煤岩体破碎的过程、特征与规律，为煤矿瓦斯高效抽采设计和增透效果评价提供有效方法和科学指导。

Coal bed methane is one of the main factors that cause the serious disasters of mine. The drainage of methane is the fundamental approach for prevention of methane disasters. The methane drainage is very difficult since the proportion of low permeability and high absorbed methane coal seam exceeds 50% of all coal seams in our country. Although several measures such as protective seam mining and high density drilling in coal seam can improve the permeability of coal seam and increase the drainage efficiency, there are still some problems during the field work, such as operation by experience and weak effectiveness, which are due to the lack of guidance of scientific theory. Not only the nonlinear large deformation but also the discontinuous behavior such as crack propagation and crushing of coal mass are encountered in the process of permeability improvement of deep coal seam. The behavior of coal mass mentioned above is short of theoretical description and computation method. Aiming at the characteristic of discontinuous and large deformation of permeability improved coal seam, this project will study on the mechanical behavior of large deformation and failure mechanism of low permeability coal based on experimental method and establish the description method of nonlinear large deformation behavior and constitutive equation. Afterwards, a theory and a numerical method which can deal with the large deformation and discontinuous behavior will be developed based on discontinuous deformation analysis. The process, characteristic and evolution law of coal seam deformation and the crack propagation and crushing of coal mass will be modeled and analyzed according to an engineering practice. The study of this project can provide an effective method and a scientific guidance for high efficient mine methane drainage design and effect evaluation of improvement permeability of coal seam.