恩洪-老厂区块中高阶煤岩微观结构特征及物性分析

为了进一步认识恩洪-老厂区块中高阶煤岩的微观结构及物性特征,分煤阶开展了扫描电镜试验、基础物性测试、巴西劈裂试验及三轴压缩试验,分析了研究区煤岩的微观结构特征,物性分布特征,变形破坏特征及强度特征。结果表明:研究区块焦煤发育有气孔及植物细胞残留孔,微观裂隙以张性裂隙为主,无烟煤主要发育有张性裂隙,张裂纹较粗糙、延伸不稳定,裂隙中可见方解石充填;研究区块无烟煤密度高于焦煤,焦煤平均孔隙度大于无烟煤,焦煤渗透率高于无烟煤,焦煤纵波和横波时差高于无烟煤;抗张试验中,焦煤煤样破坏断面呈锯齿形,主裂缝外还存在多条裂缝,破坏程度更加剧烈,无烟煤煤样断面更为平直光滑;随着围压增大,煤岩压缩破坏由多位置、高角度的原生结构面扩展破坏转变为煤岩基质的剪切破坏,峰值应变逐渐增大,抗压强度逐渐增大。

Microstructure and Physical Characteristics Analysis of Middle-High Rank Coal and Rock in Enhong-Laochang Block

In order to further understand the micro-structure and physical properties of medium-high rank coal and rock in Enhong and Laochang block, scanning electron microscope tests, basic physical property tests, Brazilian splitting tests and triaxial compression tests were carried out in different coal ranks. The microstructural characteristics, distribution characteristics of physical parameters, deformation and failure characteristics, strength characteristics of coal and rock in the investigation area were analyzed. The results show that stomata, residual stomata of plant cells can be seen, tensional fissures are the main micro-fissures in the coking coal in investigation area. Crack type of anthracite coal in investigation area is mainly tensional cracks, which are rough and unstable in extension. Calcite filling can be seen in the cracks. The density of anthracite coal is higher than that of coking coal, and the average porosity of coking coal is higher than that of anthracite coal. The permeability of coking coal is higher than that of anthracite coal. The tavel time of longitudinal wave and the travel time of transvers wave of coking coal are higher than that of anthracite coal. In tension tests, the failure section of coking coal sample is serrated, there are many cracks outside the main crack, the degree of damage is more severe, and the section of anthracite coal sample is more straight and smooth. With the increase of confining pressure, the compression failure of coal and rock changes from the expansion failure along primary structural planes of multiple locations and high angles to the shear failure of coal and rock matrix, the peak strain increases gradually, the compressive strength increases gradually.