摘要
为探究煤体孔隙结构及全孔径分形特征,借助压汞和低温液氮吸附试验,结合微焦点CT扫描系统,分别表征了取自海湾煤矿5煤(#1)和顾北煤矿中央1煤(#2)煤样的孔隙结构,并基于分形理论对比分析了煤样全孔径分布的复杂程度。结果表明:1)#1煤体孔隙结构发育,微孔至大孔都具有开放性,裂隙由上端面倾斜蜿蜒延伸至下端面,两者在空间上形成网状拓扑结构,而#2煤体存在大量孤立孔隙,微孔多属于封闭孔或半开放孔,裂隙结构数量较少,两者难以形成孔裂隙拓扑结构,不利于瓦斯渗流;2)#1,#2煤体孔隙比表面积大部分由微孔和过渡孔贡献,但两者孔容占比差异明显,#1煤体大孔、中孔孔容占比较高,而#2煤体孔容主要由微孔和过渡孔贡献;3)综合比较三种表征手段存在的缺陷,提出了可表征全孔径分形维数的新方法,得出低温液氮吸附法所表征的孔径优势区间内,#1煤体孔径分布较#2煤体的非均质性更强,即孔隙结构更为复杂,高压压汞法所表征的孔径优势区间内,#2煤体孔隙结构较#1煤体更复杂,两者在中孔范围孔隙结构的差异最为显著;微焦点CT扫描所表征的孔径优势区间内,孔隙结构非均质性大体相同,差异在于孔隙数量;4)多手段联合表征煤体孔隙结构特征,可校正高压阶段煤基质的“压缩效应”和孔裂隙压缩破坏以及微孔、过渡孔测定时的“屏蔽效应”或因样品尺寸导致大孔及可见孔被忽略而导致分形维数产生的误差,是研究及评价气固耦合和瓦斯赋存、扩散及渗流的基础。
To explore the pore structure and full pore size fractal characteristics of coal, with the help of mercury intrusion and low temperature liquid nitrogen adsorption, combined with Micro-CT scanning system, the pore structures of coal samples taken from 5coal seam in Haiwan mine(#1) and central 1 coal seam in Gubei mine(#2) were characterized respectively. The complexity of full pore size distribution of coal samples was compared and analyzed based on fractal theory. The results have shown that: 1) The pore structure of # 1 coal developed, micro-pore to macro-pore are open, and the fracture extend from the upper face to the lower end face, both of which form a reticular topological structure in space. However, there were a large number of solitary pores in #2 coal, most of micro-pores belonged to closed pores or semi-open pores, and the number of fracture structures was relatively small, which was difficult for them to form pore fracture topological structure and not conducive to gas seepage. 2) The pore specific surface area of #1 and #2 coal mass was mostly contributed by micro-pores and transition pores, but there was a significant difference in pore volume between them, that is, the volume ratio the macro-pore and meso-pore of #1 and #2 coal mass was relatively high, while the pore volume of #2 coal mass was mainly contributed by micropore and transition pore;3) After a comprehensive comparison of the defects of three characterization methods, a new method was proposed to characterize the full pore size fractal dimension. It was concluded that the pore size distribution of #1 coal was more heterogeneous than that of #2 coal, that is, the pore structure was more complex in the pore size dominant interval characterized by low temperature liquid nitrogen adsorption method. While the pore structure of #2 coal was more complex than that of #1 coal in the pore size dominant interval characterized by high pressure mercury pressure method and there was the most significant difference in pore development between the two
作者
刘怀谦
王磊
谢广祥
袁秋鹏
朱传奇
焦振华
LIU Huaiqian;WANG Lei;XIE Guangxiang;YUAN Qiupeng;ZHU Chuanqi;JIAO Zhenhua(School of Energy and Mining Engineering,China University of Mining and Technology-Beijing,Beijing 100083,China;State Key Laboratory Mine Response and Disaster Prevention and Control in Deep Coal Mine,Anhui University of Science and Technology,Huainan,Anhui 232001,China)
出处
《采矿与安全工程学报》
EI
CSCD
北大核心
2022年第3期458-469,479,共13页
Journal of Mining & Safety Engineering
基金
安徽省高校协同创新资助项目(GXXT-2020-055)
安徽省自然科学基金青年项目(1908085QE184)。
关键词
煤体
三维可视化
综合表征
孔隙形态
孔径分布
分形维数
coal mass
three-dimensional visualization
comprehensive characterization
pore morphology
pore size distribution
fractal dimension
