Effect of Unloading Stress Levels on Macro- and Microfracture Mechanisms in Brittle Rocks

doi:10.1061/(ASCE)GM.1943-5622.0001647

	Effect of Unloading Stress Levels on Macro- and Microfracture Mechanisms in Brittle Rocks
	Cong Yu 2,3; Wang Zaiquan 4; Zheng Yingren 4; Zhang Liming 1
刊名	INTERNATIONAL JOURNAL OF GEOMECHANICS
	2020-06-01
卷号	20 期号:6 页码:11
关键词	Unloading stress levels Brittle rocks Fracture mechanisms Load axial compression and unload confining pressures
ISSN号	1532-3641
DOI	10.1061/(ASCE)GM.1943-5622.0001647
英文摘要	The effect of unloading stress levels on the unloading failure mechanism is explored from both macro- and microscopic perspectives by carrying out tests to load axial compression and unload confining pressures on marble samples under different unloading stress levels and with the simulation of particle flow. The results reveal four points. First, the lower the prepeak unloading level, the lower the peak bearing capacity of rock samples after unloading; while the closer the unloading level to the peak bearing capacity, the later the occurrence of inflection point for the negative increase of volumetric strain. Second, bond energy and strain energy mainly fluctuate due to changes in unloading levels. The lower the prepeak stress level, the lower the inflection point where bond energy first increases and then decreases and the more obvious the fluctuations in strain energy from the unloading point onwards. Third, the acoustic emission (AE) event count rate increases after unloading from different stress levels. The lower the prepeak unloading stress level of specimens, the smaller the axial strain corresponding to the maximum AE event count rate. Fourth, the evolution of cracks with such a slow-rapid-slow increase does not vary with the changes in unloading stress levels. Moreover, the damage to failure caused by tensile cracks in specimens is more serious than that caused by compression-shear forces during unloading failure. There are a finite number of secondary failure surfaces inside the model at high unloading levels and the cracks caused by tensile failure are distributed over a large area. Relevant experimental results can provide theoretical basis for surrounding rock deformation control of rock underground engineering.
资助项目	National Sciences Foundation of China[41702322] ; Focus on Research and Development Plan in Shandong Province[2017GSF216010] ; Focus on Research and Development Plan in Shandong Province[2017GSF16109] ; Open Research Fund of State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences[Z016012]
WOS研究方向	Engineering
语种	英语
出版者	ASCE-AMER SOC CIVIL ENGINEERS
WOS记录号	WOS:000529974500003
内容类型	期刊论文
源URL	[http://119.78.100.198/handle/2S6PX9GI/24043]
专题	中科院武汉岩土力学所
通讯作者	Cong Yu
作者单位	1.Qingdao Univ Technol, Sch Sci, Qingdao 266033, Peoples R China 2.Chinese Acad Sci, Inst Rock & Soil Mech, State Key Lab Geomech & Geotech Engn, Wuhan 430071, Peoples R China 3.Qingdao Univ Technol, Operat Innovat Ctr Engn Construct & Safety Shando, Qingdao 266033, Peoples R China 4.Qingdao Univ Technol, Sch Civil Engn, Qingdao 266033, Peoples R China
推荐引用方式 GB/T 7714	Cong Yu,Wang Zaiquan,Zheng Yingren,et al. Effect of Unloading Stress Levels on Macro- and Microfracture Mechanisms in Brittle Rocks[J]. INTERNATIONAL JOURNAL OF GEOMECHANICS,2020,20(6):11.
APA	Cong Yu,Wang Zaiquan,Zheng Yingren,&Zhang Liming.(2020).Effect of Unloading Stress Levels on Macro- and Microfracture Mechanisms in Brittle Rocks.INTERNATIONAL JOURNAL OF GEOMECHANICS,20(6),11.
MLA	Cong Yu,et al."Effect of Unloading Stress Levels on Macro- and Microfracture Mechanisms in Brittle Rocks".INTERNATIONAL JOURNAL OF GEOMECHANICS 20.6(2020):11.