Abstract
In-situ rock failures can result from stress changes due to pure loading and/or unloading. Understanding of the damage evolution behavior in brittle rocks during loading and unloading is imperative for the designs of rock structures. In this paper, we investigate the damage evolution characteristics of a granitic rock during loading and unloading after a series of triaxial experiments performed at different confining pressures. The axial stress—axial strain variations of the tested specimens revealed that the specimens undergoing unloading fail with a lower axial strain compared to the specimens failed purely by loading. Higher confining pressures were observed to exacerbate the difference. Volumetric strain versus axial strain curves indicated that the curves reverse the trend with the beginning of major damage of specimens. We suggest here a new form of equation to describe the secant modulus variation of brittle rocks against the axial stress for the unloading process. Failure mechanisms of tested specimens showed two distinct patterns, namely, specimens under pure loading failed with a single distinct shear fracture while for the unloading case specimens displayed multiple intersecting fractures. In addition, analysis of the evolution of dissipation and elastic energy during deformation of the specimens under loading and unloading conditions showed differentiable characteristics. Moreover, we evaluated the variations of two damage indices defined based on the energy dissipation and secant modulus evolution during deformation and observed that both of them satisfactorily distinguish key stages of damage evolution.
摘要
在不同围压下进行三轴试验,研究花岗岩在加载和卸载过程中的损伤演化特征。通过分析试样 的轴向应力、轴向应变变化表明,在轴向应变较低时,试样卸荷破坏失效与加载条件下的不同。围压 越高这种不同越明显。本文提出了一种新的描述脆性岩石割线模量随轴向应力变化的方程。试件的破 坏机制表现出2 种不同的模式:在纯加载荷下,试样没有明显的剪切断裂,而卸载试样则表现出多个 相交的断裂。此外,分析了在加载和卸载条件下,试样在变形过程中的耗散和弹性能的演化规律。此 外,根据损伤过程中的能量耗散和割线模量演化来评价2 种损伤指数的变化,并观察到2 种损伤的演 化过程都能很好地区分损伤演化的关键阶段。
Article PDF
Similar content being viewed by others
Avoid common mistakes on your manuscript.
References
DU Kun, LI Xi-bing, LI Di-yuan, WENG Lei. Failure properties of rocks in true triaxial unloading compressive test [J]. Transactions of Nonferrous Metals Society of China, 2015, 25(2): 571–581. DOI: 10.1016/S1003-6326(15)63639-1.
LI Xi-bing, YAO Jin-rui, GONG Feng-qiang. Dynamic problems in deep exploitation of hard rock metal mines [J]. The Chinese Journal of Nonferrous Metals, 2011, 21(10): 2551–2563. DOI: 1004-0609(2011)10-2551-13. (in Chinese)
WAHL M H, MCKELLAR H N, WILLIAMS T M. Patterns of nutrient loading in forested and urbanized coastal streams [J]. Journal of Experimental Marine Biology and Ecology, 1997, 213(1): 111–131. DOI: 10.1016/S0022-0981(97)00012-9.
DAI Bing, HE Gui-cheng, ZHANG Zhi-jun. A numerical research on crack process of gypsum containing single flaw with different angle and length in uniaxial loading [J]. Shock and Vibration, 2018. DOI: 10.1155/2018/2968205.
DAI Bing, ZHAO Guo-yan, Dong Long-jun, YANG Chen. Mechanical characteristics for rocks under different paths and unloading rates under confining pressures [J]. Shock and Vibration, 2015. DOI: 10.1155/2015/578748.
WANG Min, CAO Ping, WAN Wen, ZHAO Yan-lin, LIU Jie, LIU Jing-shuo. Crack growth analysis for rock-like materials with ordered multiple pre-cracks under biaxial compression [J]. Journal of Central South University, 2017, 24(4): 866–874. DOI: 10.1007/s11771-017-3489-6.
YIN Tu-bing, WANG Pin, LI Xi-bing. Effects of thermal treatment on physical and mechanical characteristics of coal rock [J]. Journal of Central South University, 2016, 23(9): 2336–2345. DOI: 10.1007/s11771-016-3292-9.
WASANTHA P L P, RANJITH P G, VIETE D R. Influence of the geometry of partially-spanning joints on the uniaxial compressive strength of rock [J]. International Journal of Rock Mechanics and Mining Sciences, 2012, 50: 140–146. DOI: 10.1016/j.ijrmms.2012.01.006.
LI Xi-bing, CAO Weng-zuo, ZHOU Zi-long. Influence of stress path on excavation unloading response [J]. Tunnelling and Underground Space Technology, 2014, 42: 237–246. DOI: 10.1016/j.tust.2014.03.002.
HUANG Qiu-run, HUANG Da. Experimental research on affection laws of unloading rates on mechanical properties of Jinping marble under high geostress [J]. Chinese Journal of Rock Mechanics and Engineering, 2010, 29(1): 21–33. (in Chinese)
AYLING M R, MEREDITH P G. Microcracking during triaxial deformation of porous rocks monitored by changes in rock physical properties, I. Elastic-wave propagation measurements on dry rocks [J]. Tectonophysics, 1995, 245(3): 205–221. DOI: 10.1016/0040-1951(94)00235-2.
BAUD P, MEREDITH P G. Damage accumulation during triaxial creep of Darley Dale sandstone from pore volumometry and acoustic emission [J]. International Journal of Rock Mechanics and Mining Sciences, 1997, 34(3): 24.
EBERHARDT E, STEAD D, STIMPSON B. Identifying crack initiation and propagation thresholds in brittle rock [J]. Canadian Geotechnical Journal, 1998, 35(2): 222–233.
CAI M, KAISER P K, TASAKA Y. Generalized crack initiation and crack damage stress thresholds of brittle rock masses near underground excavations [J]. International Journal of Rock Mechanics and Mining Sciences, 2004, 41(5): 833–847. DOI: 10.1016/j.ijrmms.2004.02.001.
SUN D A, MATSUOKA H. Deformation and strength characteristics of weathered soft rock using triaxial tests [J]. International Journal of Rock Mechanics and Mining Sciences, 2004, 41: 87–92. DOI: 10.1016/j.ijrmms.2004.03. 024.
LI Jie, WANG Ming-yang, FAN Peng-xian. Study of loading-unloading states and energy distribution relationship for rock mass [J]. Rock and Soil Mechanics, 2012, 33(Supp.2): 125–132. (in Chinese)
WASANTHA P L P, RANJITH P G. Water-weakening behavior of Hawkesbury sandstone in brittle regime [J]. Engineering Geology, 2014, 178: 91–101. DOI: 10.1016/j.enggeo.2014.05.015.
SHAO S, RANJITH P G, WASANTHA P L P. Experimental and numerical studies on the mechanical behavior of Australian Strathbogie granite at high temperatures: An application to geothermal energy [J]. Geothermics, 2015, 54: 96–108. DOI: 10.1016/j.geothermics.2014.11.005.
GUO Yin-tong, YANG Chun-he, FU Jian-jun. Experimental research on mechanical characteristics of salt rock under tri-axial unloading test [J]. Rock and Soil Mechanics, 2012, 33(3): 725–732. (in Chinese)
ZHAO, X D, WANG J, CAI M, CHENG C, MA L K, SU R, ZHAO F, LI D J. Influence of unloading rate on the strain burst characteristics of Beishan granite under true triaxial unloading conditions [J]. Rock Mechanics and Rock Engineering, 2014, 47(2): 467–483. DOI: 10.1007/s00603-013-0443-2.
QIU Si-li, FENG Xia-ting. Experimental research on mechanical properties of deep-buried marble under different unloading rates of confining pressures [J]. Chinese Journal of Rock Mechanics and Engineering, 2010, 29(9): 1807–1817. (in Chinese)
ZHANG Kai, ZHOU Hui, PAN Peng-zhi, SHEN Lin-fang, FENG Xia-ting, ZHANG Yuan-gang. Characteristics of strength of rocks under different unloading rates [J]. Rock and Soil Mechanics, 2010, 31(7): 2072–2078. (in Chinese)
ULUSAY R, HUDSON J. A ISRM. The complete ISRM suggested methods for rock characterization, testing and monitoring: 1974–2006. [C]// Commission on Testing Methods International Society of Rock Mechanics. Turkey: Ankara: ISRM Turkish National Group, 2007: 628.
LAJTAI E Z, CARTER B J, DUNCAN E S. Mapping the state of fracture around cavities [J]. Engineering Geology, 1991, 31(3): 277–289. DOI: 10.1016/0013-7952(1)90012-A.
CHEN Wei, KONIETZKY H, TAN Xin. Pre-failure damage analysis for brittle rocks under triaxial compression [J]. Computers and Geotechnics, 2016, 74: 45–55. DOI: 10.1016/j.compgeo.2015.11.018.
ZHAO Guo-yan, DAI Bing, DONG Long-jun. Energy conversion of rocks in process of unloading confining pressure under different unloading paths [J]. Transactions of Nonferrous Metals Society of China, 2015, 25(5): 1626–1632. DOI: 10.1016/S1003-6326(15)63767-0.
HUANG D, LI Y. Conversion of strain energy in triaxial unloading tests on marble [J]. International Journal of Rock Mechanics and Mining Sciences, 2014, 66: 160–168.
XIE He-ping, PENG Rui-dong, JU Yang. On energy analysis of rock failure [J]. Chinese Journal of Rock Mechanics and Engineering, 2015, 24(15): 2603–2608. (in Chinese)
XIE He-ping, JU Yang, PENG Rui-dong. Energy mechanism of deformation and failure of rock masses [J]. Chinese Journal of Rock Mechanics and Engineering, 2008, 27(9): 1729–1739. (in Chinese)
Author information
Authors and Affiliations
Corresponding author
Additional information
Foundation item: Projects(51774187, 51324744, 51374129) supported by the National Natural Science Foundation of China; Project(71380100006) supported by the Innovation Foundation of Doctoral Student in Hunan Province, China; Project(2017SK2280) supported by the Key Research and Development Program of Hunan Provincial Science and Technology Department, China; Project(17A184) supported by the Key Research Foundation of Education Bureau of Hunan Province, China
Rights and permissions
About this article
Cite this article
Dai, B., Zhao, Gy., Konietzky, H. et al. Experimental investigation on damage evolution behaviour of a granitic rock under loading and unloading. J. Cent. South Univ. 25, 1213–1225 (2018). https://doi.org/10.1007/s11771-018-3819-3
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s11771-018-3819-3