层理和预制裂纹方向对煤断裂力学性质影响规律试验研究

doi:10.13722/j.cnki.jrme.2021.0735

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Abstract To study the coupling influences of bedding and pre-crack directions on the fracture characteristics of coal，quasi-static loading experiments on SCB coal specimens with pre-crack were conducted，and the acoustic emissions during deformation and failure process were monitored. Regarding coal as a transversely isotropic body，the dimensionless factor was calibrated by finite element code，and the fracture toughness more in line with the actual situation was obtained. The results indicate that different combinations of bedding and pre-crack direction lead to significant differences in the loading curves and the fracture loads of specimens. In addition，the fracture modes and the fracture toughness are jointly affected by the bedding and the pre-crack direction. Meanwhile，the fracture toughness declines with decreasing the angle between the bedding and the loading direction，and the inclined pre-crack further weakens the resistance ability of specimens against crack propagation. Tensile failure dominates the crack initiation and propagation，and the propagation path of specimens shows significant anisotropy. According to the final crack morphology，the macroscopic failure modes of specimens can be divided into 4 types. The number of acoustic emission hits corresponds to the loading history，and the average total hit number at post-fracture load(including fracture load) stage varies obviously with the change of the pre-crack direction due to the different structure failure. Under external loading，specimens are damaged with tensile and shear micro-cracks continuously generating inside the specimens. The damage evolution is tightly related to the bedding and pre-crack directions. At different loading levels，tensile micro-cracks play a domination role，while the proportion of the shear micro-cracks is relatively low. With increasing the loading level，the micro-cracks continue to develop and propagate，and the damage of the specimens accumulates continuously，resulting in the crack initiation and failure.

Key words： rock mechanics bedding direction pre-crack direction transversely isotropic acoustic emission

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	WANG Wei1
	2
	ZHAO Yixin1
	2
	GAO Yirui1
	2
	ZHANG Cun1
	2

Cite this article:

WANG Wei1,2,ZHAO Yixin1, et al. Experimental research of influences of bedding and pre-crack directions on fracture characteristics of coal[J]. , 2022, 41(3): 433-445.

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https://rockmech.whrsm.ac.cn/EN/10.13722/j.cnki.jrme.2021.0735 OR https://rockmech.whrsm.ac.cn/EN/Y2022/V41/I3/433

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