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| Experimental study on incubation and acoustic emission characteristics of rock fracture process zones |
| AN Dingchao1，ZHANG Sheng1，2，ZHANG Xulong1，YU Bingxin1，WANG Hongyue1 |
(1. College of Energy Science and Engineering，Henan Polytechnic University，Jiaozuo，Henan 454000，China；2. The Collaborative Innovation Center of Coal Safety Production of Henan Province，Jiaozuo，Henan 454000，China)
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Abstract In order to study the inoculation law and acoustic emission characteristics of rock fracture process zones，straight-crack disc sandstone samples were used for the split loading test on the GCTS rock test system，the real-time monitoring was performed with the help of digital image correlation method(DICM) and acoustic emission(AE) instrument，and the lengths of sample fracture process zones were obtained according to the change of the horizontal displacement of measuring lines near crack tips and the AE event locations. The theoretical value of the fracture process zone length was determined based on the high-order term of Williams series expansion as well as the revised maximum tangential stress criterion，and the failure morphology of the specimens was discussed. The results show that the average values of the fracture process zone length determined by DICM and theoretical calculation are respectively 9.07 mm and 5.19 mm，and the difference between them is due to that the theory method fails to consider the influence of the microscopic characteristics of the rock and the loading method. The load corresponding to the maximal incubation degree in the fracture process is very closer to the plastic yield point load，about 92.19%–95.47% of the peak load. The inoculation and development process of the micro-cracks of the specimen crack tips during loading is reflected by the acoustic emission signals，and the length of the specimen fracture process zone determined by the acoustic emission positioning point has good consistency with DICM. The research work is helpful to understand in depth the inoculation law of rock fracture process zones.
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2021, Vol. 40 
