Dynamic evolution characteristics and fractal law of loaded coal fractures by micro industrial CT
WANG Dengke1，2，3，4，ZENG Fanchao1，3，WANG Jianguo2，WEI Jianping1，3，4，JIANG Zhigang5，WANG Xiaobing5，ZHANG Ping1，3，YU Chong1，3#br#
(1. State Key Laboratory Cultivation Base for Gas Geology and Gas Control，Henan Polytechnic University，Jiaozuo，Henan 454000，China；2. State Key Laboratory for GeoMechanics and Deep Underground Engineering，China University of Mining and Technology，Jiangsu，Xuzhou 221116，China；3. School of Safety Science and Engineering，Henan Polytechnic University，Jiaozuo，Henan 454000，China；4. The Collaborative Innovation Center of Coal Safety Production of Henan，Jiaozuo，Henan 454000，China；5. Sichuan Coal Industry Group Limited Liability Company，Chengdu，Sichuan 610091，China)
摘要为观测受载煤样裂隙演化过程，利用受载煤岩工业CT扫描系统对煤样单轴压缩破坏过程进行CT实时扫描实验，将CT扫描图片导入VG Studio MAX图像分析软件进行煤样的三维数字化模型重建，得到煤样内部裂隙空间的分布情况。运用MATLAB软件通过分析和计算得到了煤样内部结构的灰度直方图和裂隙分形维数，综合分析煤样裂隙的动态演化特征和分形规律。研究结果表明：利用灰度直方图和VG Studio MAX软件分析结果能有效地定性和定量描述受载煤样内部裂隙动态发展的总体变化规律；全应力应变过程中，受载煤样的断面裂隙面积、断面裂隙谱峰面积和三维裂隙体积总体上呈先减小后增加的变化趋势，真实客观地反映了煤样内部裂隙结构的动态演化规律，充分体现了外部载荷和变形对裂隙发展的控制作用；裂隙分形维数主要经历了缓慢降低、平稳增加、大幅突增和缓慢升高4个发展阶段，有效刻画了受载煤样内部裂隙的演变发展过程，其变化规律与裂隙动态变化规律保持了良好的一致性，可用于受载煤样失稳破坏的预测。
Abstract：In order to observe the evolution process of loaded coal fractures，CT real-time scanning test of coal samples during the uniaxial compression process through using a CT scanning system of the loaded coal-rock industry was carried out，and the CT scanning images were imported into VG Studio MAX image analysis software to reconstruct 3D digital model of coal and further to obtain the spatial distributions of fractures within coal samples. The gray histogram of coal sample internal structure and fracture fractal dimension are obtained by analysis and calculation with MATLAB software，and the dynamic evolution characteristics and fractal law of fractures in coal samples are analyzed comprehensively. The results show that the analysis results of gray-scale histogram and VG Studio MAX software can be used to qualitatively and quantitatively describe the dynamic development of fractures in coal samples. In the total stress-strain process，the fracture area，peak area of fracture spectrum and three-dimensional fracture volume of the loaded coal sample decrease first and then increase，which truly and objectively reflects the dynamic evolution law of the fracture structure in coal samples and fully reflects the control effect of external load and deformation on the fracture development. The fracture fractal dimension mainly experiences four development stages including slow decrease，steady increase，large sudden increase and slow increase，which is consistent with the fracture dynamic change law，can effectively depicts the evolution and development process of internal fractures of the loaded coal sample，and hence can be used to predict the instability and failure of loaded coal samples.
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2020, Vol. 39 
