构造煤结构演化及其应力-应变环境

Evolution of Textures and Stress-Strain Environments of Tectonically-Deformed Coals

基于不同变形类型和程度煤样品的X射线衍射分析(XRD),研究了构造煤的结构演化及其应力-应变环境。结果显示,弱变形构造煤芳香结构参数面网间距(d002)随煤化程度增高呈阶跃式减小,阶跃点为最大油浸镜质组反射率等于0.69%左右,阶跃点后变化不大;鳞片煤Ⅱ的面网间距最小,揉皱糜棱煤与片状碎裂煤Ⅱ相当,介于弱变形构造煤与鳞片煤Ⅱ之间,揉皱煤的面网间距稍大于揉皱糜棱煤;堆砌度随煤芳香结构演化与面网间距协调变化。认为应力-应变作用类型和程度的差异控制了不同变形类型和程度构造煤的形成,应力-应变作用不仅改变煤体宏观和微观结构,也影响着煤芳香结构的演化,且不同类型和程度应力-应变作用的影响程度存在较大差异。形成构造煤的应力-应变环境可分为脆性碎裂变形环境、韧性变形环境和剪切变形环境三类。弱和中等脆性碎裂变形作用对煤芳香结构影响不大;韧性和剪切变形作用分别以一定的温压条件和定向的应力作用为主要特征,前者有利于煤中杂原子团的脱落和新芳环的形成,后者有助于煤中分子结构的有序化,均可促进煤中芳核的生长。

Based on X-ray Diffraction （XRD） analysis of tectonically-deformed coals with different deformation types and extent, the evolution of the tectonically-deformed coals and their stress-strain environments were studied. The results show that the space between aromatic layers（d002） of weak-deformed coals decrease in stepfunction with the step point of about R =0.69%, as the rank of coalification increases, and change a little following the step point; the d002 of scaly coal ]] is smallest, crumpled-mylonitic coal＇ s d0o2, which is almost equal to flaky coal 1]＇ s d0o2, is between the d002 of weak-deformed coals and scaly coal ]I, and the d0o： of crumpled coal is slightly larger than that of crumpled-mylonitic coal. The other parameter Lc changes in a coordinate way with d00〉 It is indicated that tectonically-deformed coals with various deformation types and extent are corresponding to different types and extent of stress-strain action, which change the macro- and microtexture of coal as well as the texture of aromatic nucleus. The effect of each stress-strain environment upon the aromatic nucleus of coal is different. The stress-strain environments forming tectonically-deformed coals can be classified into three types, i.e. brittle cataclastic, ductile, and shearing. Weak and moderate brittle cataclastic deformation actions have little effects on the development of aromatic nucleus of coal. Ductile and shearing deformation actions are featured by conditions of certain temperature and confining pressure and directional stress action,respectively. The former are benefit for shedding of small radicles and developing of new aromatic rings, the later are helpful to the ordering of molecular structure. Both of them promote the growth of aromatic nucleus in coal.