单轴加载煤孔裂隙各向异性核磁共振特征  

Anisotropic characteristics of nuclear magnetic resonance of pores and fractures in coal under uniaxial loading

作　　者：卢方超 张玉贵[1,2] 江林华[1,2] 

机构地区：[1]河南理工大学安全科学与工程学院,河南焦作454000 [2]河南理工大学瓦斯地质研究所,河南焦作454000

出　　处：《煤田地质与勘探》2018年第1期66-72,共7页Coal Geology & Exploration

基　　金：国家科技重大专项课题(2016ZX05067-006);河南省高校科技创新团队支持计划(14IRTSTHN002)~~

摘　　要：为了研究煤孔裂隙各向异性,进一步揭示煤微观结构及物性特征。选取平顶山矿区八矿煤样,采用核磁共振(NMR)方法,对比分析单轴加载前后煤样的横向弛豫谱(T2)特征和核磁成像(MRI)特征。实验结果表明,煤的T2谱特征具有显著的各向异性:平行于层理且垂直主裂隙X方向T2谱为3峰谱图,平行于层理且平行主裂隙Y方向T2谱为双峰谱图,垂直层理Z方向T2谱主要以单峰为主;单轴加载后煤样T2谱面积、孔隙度减小,X、Y方向煤样孔隙变化引起的峰面积所占比例下降,裂隙变化引起的峰面积占比例上升;Z方向裂隙变化引起的峰面积占比例下降;MRI揭示出,单轴加载后平行层理方向煤样孔裂隙大部分闭合,部分裂隙产生径向变形;加载方向裂隙大部分闭合,压实效应显著。综上所述,单轴加载下,煤样各向异性特征显著,同时表明核磁共振技术是研究煤孔裂隙微观变化的有效手段。In order to study the anisotropy of coal pores and fractures, further reveal the microstructure and physical characteristics of coals, coal samples were collected from Pingdingshan eighth mining area for nuclear magnetic resonance（NMR）experiments, transverse relaxation time（T2）and magnetic mesonance imaging（MRI） under uniaxial loading were compared and analyzed. The results showed that T2 was remarkably anisotropic： parallel to bedding and in direction X of vertical main fractures, T2 had three peaks, parallel to bedding and direction Y of main fractures, T2 had two peaks, vertical to direction Z of bedding T2 had one peak. After uniaxial loading, the spectral area of T2 and the porosity decreased, the percentage of peak area induced by porosity variation in direction X and Y declined, but the fracture areas ascended, the fracture area in direction Z declined. The MRI revealed that under uniaxial loading, most pores and fractures parallel to bedding were closed, some fractures had radial deformation, most fractures of loading direction were closed, the compaction effects was remarkable. In summary, under uniaxial loading, the anisotropic characteristics of coal samples were remarkable, and the NMR was an effective method to study microscopic changes of coal pores and fractures.

关 键 词：孔裂隙 核磁共振 各向异性 单轴加载 核磁成像 

分 类 号：P618.13[天文地球—矿床学]