煤是对应力和应变非常敏感的一种特殊岩石,在不同的应力-应变环境和构造应力作用下,煤的物理结构、化学结构及其光性特征等都将发生显著变化,从而形成具有不同结构特征的、不同类型的构造煤。构造煤在变形的过程中,镜质组反射率将发生规律性变化,并被较为广泛地应用于煤田构造的定量研究,高温高压变形实验也证实了这一现象。为了深入探讨煤镜质组光性组构变化的微观机理,将X-射线衍射、顺磁共振和核磁共振等技术应用于不同类型构造煤以及高温高压实验变形煤的化学结构研究。研究表明,构造煤化学结构演化与镜质组反射率的演化具有密切的内在联系,镜质组反射率的光性异常是构造煤化学结构演化在物理光学性质上的具体体现。不同类型的构造煤由于物理和化学结构上的不同,导致瓦斯含量和透气性等瓦斯特性上的重大差异,糜棱煤特殊的物理和化学结构决定了其高含气量和低透气性的特征,是矿井瓦斯突出的危险地带,因此,可以通过构造煤分布规律的研究,进行矿井瓦斯富集与突出危险性的评价与预测,为矿井瓦斯灾害的研究提供新的思路和方法。
Coal is a special kind of rock that is sensitive to stress and strain. Under different stress-strain environment and tectonic stress effect, the physical structure, chemical structure, characteristic of optical property, etc. of coal will greatly be changed, and tectonic coal with different structural characteristics and types will be formed. Vitrinite reflectance changes regularly during the process of tectonic coal deformation, which is extensively applied to the quantitative analysis of coalfield structure. This is also confirmed by deformation experiments under high temperature and confining pressure. In order to further investigate the microscopic mechanism of the change of vitrinite optical fabric, X-ray diffraction, paramagnetic resonance and nuclear magnetic resonance were used to study the chemical structure of different types of tectonic coal and experimentally deformed coals under high temperature and confining pressure. Research shows that there is a close internal relation between the evolution of tectonic coal chemical structure and the vitrinite reflectance. The optical property anomaly of vitrinite reflectance is a concrete manifestation of chemical structure evolution of tectonic coal in physical optical property. Different physical and chemical structure in different types of tectonic coal resulted in a great difference in the characteristics such as gas content, permeability, etc. Mylonitic coal developed area is a dangerous belt for gas outburst in coal mine because of its high gas content and low permeability which are determined by special physical and chemical structures. Therefore, we can evaluate and predict the enrichment of mine gas and outburst hazard through studying distribution laws of tectonic coal. It provides a new thought and method for research on mine gas disaster.