Analysis of coal fracture evolution characteristics under different loading rates

doi:10.16265/j.cnki.issn1003-3033.2022.11.2690

Abstract

Abstract:

In order to study the influence of loading rate on the evolution of coal fracture, uniaxial compression tests of coal under different loading rates were carried out. Taking raw coal samples as the research object, the relationship between coal mechanical parameters, deformation field evolution cloud map and acoustic emission signal parameters was analyzed by combining digital speckle technology and acoustic emission technology. The research shows that the compressive strength and elastic modulus of coal increase gradually with the increase of loading rate. The compressive strength increases by 25.49%, and the elastic modulus increases by 51.55%. The evolution nephogram of the coal deformation field and the spatial distribution of acoustic emission events can indicate the whole process of fracture development, expansion and fracture. With the increase of loading rate, the failure type of coal body changes from tensile failure to tensile shear composite failure. The relative displacement rate of the localization zone of the coal surface deformation field decreases gradually, and the peak count, peak energy and the number of acoustic emission events increase, while the cumulative count and cumulative energy decrease. The evolution nephogram of the deformation field and the spatial distribution of acoustic emission events can better reflect the evolution characteristics of fracture development, expansion and fracture during coal loading.

Key words: loading rate, coal, fracture evolution, evolution characteristics, uniaxial compression test, acoustic emission events

XIAO Peng, GAO Zhen, SHUANG Haiqing, WU Mingchuan, CHENG Yueying, GUO Chenhua. Analysis of coal fracture evolution characteristics under different loading rates[J]. China Safety Science Journal, 2022, 32(11): 65-73.

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References 20

[1]	袁亮. 煤炭精准开采科学构想[J]. 煤炭学报, 2017, 42(1):1-7.
	YUAN Liang. Scientific conception of precision coal mining[J]. Journal of China Coal Society, 2017, 42(1):1-7.
[2]	付玉平, 李川田, 庞杰文, 等. 大采高工作面顶板破坏规律的推进速度效应[J]. 煤炭技术, 2022, 41(2):14-17.
	FU Yuping, LI Chuantian, PANG Jiewen, et al. Advancing speed efficency of roof failure law in large mining height working face[J]. Coal Technology, 2022, 41(2):14-17.
[3]	高明忠, 刘军军, 林文明, 等. 特厚煤层超前采动原位应力演化规律研究[J]. 煤炭科学技术, 2020, 48(2):28-35.
	GAO Mingzhong, LIU Junjun, LIN Wenming, et al. Study on in-situ stress evolution law of ultra-thick coal seam in advance mining[J]. Coal Science and Technology, 2020, 48(2):28-35.
[4]	李福林, 杨健, 刘卫群, 等. 单轴压缩条件下泥岩加载速率变化效应研究[J]. 岩土力学, 2021, 42(2):369-378.
	LI Fulin, YANG Jian, LIU Weiqun, et al. Effect of loading rate changing on the mechanical properties of mudstone under uniaxial compression[J]. Rock and Soil Mechanics, 2021, 42 (2):369-378.
[5]	苏承东, 李怀珍, 张盛, 等. 应变速率对大理岩力学特性影响的试验研究[J]. 岩石力学与工程学报, 2013, 32(5):943-950.
	SU Chengdong, LI Huaizhen, ZHANG Sheng, et al. Experimental investigation on effect of strain rate on mechanical characteristics of marble[J]. Chinese Journal of Rock Mechanics and Engineering, 2013, 32 (5):943-950.
[6]	LIANG Weiguo, ZHAO Yangsheng, MAURICE B, et al. Effect of strain rate on the mechanical properties of salt rock[J]. International Journal of Rock Mechanics and Mining Sciences, 2011, 48(1):161-167.
[7]	宋义敏, 邢同振, 邓琳琳, 等. 不同加载速率下岩石变形场演化试验研究[J]. 岩土力学, 2017, 38(10):2773-2779,2 788.
	SONG Yimin, XING Tongzhen, DENG Linlin, et al. Experimental study of evolution characteristics of rock deformation field at different loading rates[J]. Rock and Soil Mechanics, 2017, 38(10):2773-2779,2 788.
[8]	张天军, 景晨, 王喜娜, 等. 不同加载速率对含孔试样变形特性影响研究[J]. 采矿与安全工程学报, 2021, 38(4):1-12.
	ZHANG Tianjun, JING Chen, WANG Xi'na, et al. Experimental investigation of the effect of different loading rates on deformation characteristics of porous samples[J]. Journal of Mining and Safety Engineering, 2021, 38(4):1-12.
[9]	赵敖寒, 马衍坤, 刘健, 等. 瓦斯环境中煤体破裂AE信号频带能量特征研究[J]. 中国安全科学学报, 2020, 30(3):115-121. doi: 10.16265/j.cnki.issn1003-3033.2020.03.018
	ZHAO Aohan, MA Yankun, LIU Jian, et al. Energy characteristics of AE signal frequency band during coal rupture in mines with gas[J]. China Safety Science Journal, 2020, 30(3):115-121. doi: 10.16265/j.cnki.issn1003-3033.2020.03.018
[10]	JIANG Deiyi, CHEN Jie, REN Song, et al. A damage constitutive model of rock salt based on acoustic emission characteristics[C]. Clean Energy System in Subsurface: Production, Storage and Conversion, 2013:363-377.
[11]	MANSUROV V A. Acoustic emission from failing rock behavior[J]. Rock Mechanics and Rock Engineering, 1994, 27(3): 173-182. doi: 10.1007/BF01020309
[12]	KNILL J L, FRANKLIN J A, MALONE A W. A study of acoustic emission from stressed rock[J]. International Journal of Rock Mechanics and Mining Sciences and Geomechanics Abstracts, 1968, 5(1):87-88. doi: 10.1016/0148-9062(68)90025-9
[13]	赵兴东, 李元辉, 袁瑞甫, 等. 基于声发射定位的岩石裂纹动态演化过程研究[J]. 岩石力学与工程学报, 2007, 26(5):944-950.
	ZHAO Xingdong, LI Yuanhui, YUAN Ruifu, et al. Study on crack dynamic propagation process of rock samples based on acoustic emission locaatoin[J]. Chinese Journal of Rock Mechanics and Engineering, 2007, 26(5):944-950.
[14]	MA Yankun, WANG Enyuan. Acoustic emission generated during the gas sorption-desorption process in coal[J]. International Journal of Mining Science and Technology, 2012, 22(3):391-397. doi: 10.1016/j.ijmst.2011.11.001
[15]	LIU Quansheng, JIE Xu, LIU Xuewei, et al. The role of flaws on crack growth in rock-like material assessed by AE technique[J]. International Journal of Fracture, 2015, 193(2):99-115. doi: 10.1007/s10704-015-0021-6
[16]	CHMEL A, SHCHERBAKOV L. A comparative acoustic emission study of compression and impact fracture in granite[J]. International Journal of Rock Mechanics and Mining Science, 2013, 64:56-59.
[17]	孙爱琴, 胡明明, 华建兵, 等. 砂岩单轴循环加卸载过程中声发射信号特征与时空演化规律[J]. 河海大学学报:自然科学版, 2019, 47(5):462-467.
	SUN Aiqin, HU Mingming, HUA Jianbing, et al. Characteristics of acoustic emission signals and spatiotemporal evolution law in the process of uniaxial cyclic loading and unloading process of sandstone[J]. Journal of Hohai University:Natural Sciences, 2019, 47 (5):462-467.
[18]	左建平, 裴建良, 刘建锋, 等. 煤岩体破裂过程中声发射行为及时空演化机制[J]. 岩石力学与工程学报, 2011, 30(8):1564-1570.
	ZUO Jianping, PEI Jianliang, LIU Jianfeng, et al. Investigation on acoustic emission behavior and its time-space evolution mechanism in failure process of coal-rock combined body[J]. Chinese Journal of Rock Mechanics and Engineering, 2011, 30(8):1564-1570.
[19]	国际岩石力学学会实验室和现场试验标准化委员会. 岩石力学试验建议方法[M]. 郑雨天, 傅冰骏,译. 北京: 煤炭工业出版社, 1982:2-5.
	International Society for Rock Mechanics Commission on Standardization of Laboratory,Field Tests. Suggested methods rock mechanics test[M]. ZHENG Yutian, FU Bingjun,Translated. Beijing: China Coal Industry Publishing House, 1982:2-5.
[20]	曹安业, 井广成, 窦林名, 等. 不同加载速率下岩样损伤演化的声发射特征研究[J]. 采矿与安全工程学报, 2015, 32(6):923-928,935.
	CAO Anye, JING Guangcheng, DOU Linming, etc. Damage evolution law based on acoustic emission of sandy mudstone under different uniaxial loading rate[J]. Journal of Mining & Safety Engineering, 2015, 32(6):923-928,935.

加载速率/ (mm·min^-1)	相对位移速率最大量值/(mm·s^-1)
加载速率/ (mm·min^-1)	A1-A2	B1-B2	C1-C2
0.05	0.622	0.704	-
0.10	0.430	0.312	0.195
0.50	0.258	0.249	-
1.00	0.051	0.083	-

加载速率/ (mm·min^-1)	声发射峰值计数/个	声发射累计计数/个	声发射峰值能量/(mV·ms)	声发射累计能量/(mV·ms)	声发射事件累计数/个
0.05	225	267 344	1 005	29 765	2 090
0.10	293	102 902	1 504	24 577	1 224
0.50	414	65 064	2 229	10 185	890
1.00	1 262	25 861	3 347	8 825	786