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| Experimental research on cracking process of coal under temperature variation with industrial micro-CT#br# |
| WANG Dengke1，2，3，4，ZHANG Ping1，3，PU Hai2，WEI Jianping1，3，4，LIU Shumin1，3， YU Chong1，3，SUN Liutao1，3 |
| (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，Xuzhou，Jiangsu 221116；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) |
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Abstract The mechanism and characteristics of coal cracking under temperature shock was studied with micro-CT. The high-low temperature test system SLX–80 was used to exert the cold and heat shock on the raw coal with four temperature differences designated. The industrial micro-CT system was used to scan the coal samples before and after the temperature shock so that three-dimensional fracture structure of coal samples may be reconstructed with the image analysis system VG Studio MAX. The characteristics of cracking process were described quantitatively. The transient thermal stress theory was used to analyze the coal breaking mechanism under temperature shock. The results show that the temperature shock promotes the expansion and widening of cracks within the coal body and initiates new cracks. The crack volume，wall thickness and surface area are all positively correlated with the temperature difference，indicating that the thermal stress generated by different temperature differences determines the degree of damage of coal samples. A large number of acoustic emission signals were generated in the process of temperature shock and mainly concentrated in the first 600 s. The greater the temperature difference is，the higher the acoustic emission energy. The maximum thermal stress generated is tangential to the coal surface. The thermal stress exceeding the tensile strength of coal samples cause directly the initiation，propagation，and interpenetration of fissures.
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2018, Vol. 37 
