单轴受压条件下煤岩非均质性对其破坏特征的影响

Influence of heterogeneity on the failure characteristics of coal under uniaxial compression condition

以忻州窑14号煤为研究对象,基于波速测试、CT扫描和三维重构技术,分析了煤岩内部原生裂隙、孔隙以及矿物夹杂分布的非均质特征,研究了单轴受压条件下,沿不同方向加载时,煤样内部结构分布的非均质性对煤岩破坏特征的影响。研究发现,煤样内部原生裂隙、孔隙以及矿物夹杂分布方向的非均质性是造成不同加载方向上煤岩破坏特征差异性的原因:煤样内部原生裂隙、矿物夹杂沿层理方向分布和延伸,造成沿垂直层理加载煤样的单轴抗压强度、总声发射计数等参数的均值高于沿平行层理加载的煤样;割理的横向截割作用使沿垂直割理加载煤样整体性低于沿平行割理加载煤样,并造成其单轴抗压强度,总声发射计数等参数的均值以及加载过程中声发射现象的规律性略低于后者;煤样单轴抗压强度与纵波波速呈指数函数关系,煤样内部非均质性对其单轴抗压强度的影响可由非均质系数表示,且2者呈负相关。

Based on the P-wave velocity test,CT scanning and three-dimensional reconstruction technology,the distribution heterogeneity of cracks and mineral inclusions in coal sample,obtained from the No. 14 coal in Xinzhou Mine,was researched,and the failure characteristics of coal samples loaded in different directions effected by its heterogeneity were also investigated,according to the uniaxial experiment when the coal samples loaded in various directions.Results indicate that the distribution heterogeneity of microstructures in coal sample leads to the difference of failure characteristics loading in different directions. The primary fractures and mineral inclusions are distributed and extended along the bedding plane,the average uniaxial compressive strength,total AE count,and other parameters are loaded perpendicular to bedding plane higher than that parallel to bedding plane,at the same time,the transverse cutting effect of cleats makes the parameters of mentioned above and the regularity of AE in the loading process loaded perpendicular to cleats lower than the coal samples been loaded parallel to the cleats.The UCS and the P-wave velocity ofthe coal sample have an exponential function relation,and the effect of heterogeneity inside the coal sample on the UCS can be reflected by the heterogeneity coefficient,and the heterogeneity coefficient has a negative correlation with the UCS of the coal.