Tensile failure characteristics of coal after the cyclic cold shock of liquid nitrogen

被引：0

作者：

Chen A. ^{[1
,2
]}

Zhai C. ^{[1
,2
]}

Cong Y. ^{[1
,2
]}

Sun Y. ^{[1
,2
]}

Zheng Y. ^{[1
,2
]}

机构：

[1] School of Safety Engineering, China University of Mining and Technology, Jiangsu, Xuzhou

[2] National Engineering Research Center for Coal Gas Control, China University of Mining and Technology, Jiangsu, Xuzhou

来源：

Zhongguo Kuangye Daxue Xuebao/Journal of China University of Mining and Technology | 2023年 / 52卷 / 02期

关键词：

acoustic emission; coal; cyclic cold shock of liquid nitrogen; digital image correlation; tensile failure;

D O I：

10.13247/j.cnki.jcumt.20210858

中图分类号：

学科分类号：

摘要：

In order to study the tensile failure characteristics of coal after the cyclic cold shock of liquid nitrogen (LN2), ultrasonic tests and Brazilian splitting tests were carried out on the coal samples with 0, 2, 4, 6, 8, and 10 times of LN2cold shocks. The related physical parameters such as longitudinal wave velocity, tensile strength, failure modes, crack density and fractal dimension of the coal samples were analyzed, and the influence of the cold shock times of LN2on the stress field and the characteristics of the acoustic emission time-domain parameters of the coal samples subjected to tensile failure was studied. The results indicate that the coal samples are broken in several stages and show a more obvious yield stage after cold shock. With the increase of the cold shock times, the longitudinal wave velocity and tensile strength of the coal samples gradually decrease, which drop to 37% and 30. 72% of the initial values after 10 times of cold shocks, respectively. The maximum strain on the surface of the coal samples gradually increase with cold shock times, and the failure mode evolve from ' line ' to 'network'. In addition, the crack density increase from 32.11 m-1to 113.75 m-1after 10 times of cold shocks, while the fractal dimension increase from 1.15 to 1.49. There is a sudden change in the ringing count of acoustic emission during the slow increase period of the coal samples after cold shock. The number of the ringing count increase first and then drop with the increase of the cold shock times, reaching the maximum value after 6 times of cold shocks, and then the peak value of it decrease gradually. The cumulative energy curve of the coal samples shows a step increase after cold shock, and the cumulative energy peak increase first and then decrease with the cold shock times. The existence of the weak structural area may be the prime reason for the staged destruction of the coal samples, the evolution of the failure mode to the 'network' type and the sudden change of the ringing count of acoustic emission. © 2023 China University of Mining and Technology. All rights reserved.

引用

页码：342 / 353

页数：11

共 33 条

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