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| 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)
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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 
