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| Investigation on fracture evolution of pre-flawed hollow-cylinder granite under increasing-amplitude cyclic loads
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| WANG Yu1，2，YANG Haonan1，2，YI Xuefeng1，2，LI Juzhou1，2，LI Changhong1，2 |
| (1. Beijing Key Laboratory of Urban Underground Space Engineering，University of Science and Technology Beijing，Beijing 100083，China；2. Key Laboratory of Ministry of Education for Efficient Mining and Safety of Metal Mines，University of Science and Technology Beijing，Beijing 100083，China) |
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Abstract This work aims to reveal the fracture evolution characteristics and the meso-mechanical mechanism of the pre-flawed hollow cylinder granite subjected to stress disturbance with a kind of medium-low strain rate，and to further investigate the fracture and instability process of the cavity-fissure composite rock mass commonly encountered in underground engineering. Typical four hollow cylinder specimens with different prefabricated flaw angles were tested using the CTS-RTR 2000 rock mechanics testing system，the real-time acoustic emission(AE) monitoring and the post-test computed tomography(CT) scanning technique. The experimental results show that：(1) The rock fatigue strength，the volume deformation and the fatigue life gradually increase with the flaw angle，and the growth rate of the volume deformation becomes faster. Using the irreversible axial strain，a two-stage damage evolution model was proposed to describe the fatigue damage of rock. (2) The AE count and energy in the process of rock fracture are affected by the angle of two fissures. The cumulative count and accumulated energy count increase with increasing the fissure angle. The cumulative damage of rock at the moment of the sudden increase of stress amplitude is greater than that at the fatigue loading stage. (3) Post-test CT scanning reveals different fracture modes formed from the rock bridge segment，which is greatly affected by the fissure angle. The complexity of the fracture network increases with the increase of the fissure angle，indicating that the rock is different to be fractured with a larger fissure angle. The experimental results are helpful in understanding the fatigue failure mechanism of pre-flawed hollow rock，and provide necessary theoretical supports for the tunnel excavation design，the stability control of surrounding rocks and the long-term stability of jointed rock mass exposed to stress disturbance.
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| [1] MARTINI C D，READ R S，MARTINO J B. Observations of brittle failure around a circular test tunnel[J]. International Journal of Rock Mechanics and Mining Sciences，1997，34(7)：1 065–1 073.
[2] ZIMMERMANN G，ZANG A，STEPHANSSON O，et al. Permeability enhancement and fracture development of hydraulic in situ experiments in the ?sp? Hard Rock Laboratory[J]. Rock Mechanics and Rock Engineering，2019，52(2)：495–515.
[3] WU H，KULATILAKE P H，ZHAO G，et al. Stress distribution and fracture evolution around a trapezoidal cavity in sandstone loaded in compression[J]. Theoretical and Applied Fracture Mechanics，2019，104，102348.
[4] JABER J，CONIN M，DECK O，et al. Investigation of the mechanical behavior of 3D printed polyamide—12 joints for reduced scale models of rock mass[J]. Rock Mechanics and Rock Engineering，2020，53(1)：1–19.
[5] HU J，LI S，LIU H，et al. New modified model for estimating the peak shear strength of rock mass containing nonconsecutive joint based on a simulated experiment[J]. International Journal of Geomechanics，2020，20(7)：04020091.
[6] SUN P P，YANG X X，SUN D K，et al. Geometric and mechanical properties of a shear-formed fracture occurring in a rock bridge between discontinuous joints[J]. Bulletin of Engineering Geology and the Environment，2019，79(3)：1–16.
[7] HOEK E. Rock fracture under static stress conditions[Ph. D. Thesis][D]. South Africa：University of Cape Town， 1965.
[8] WANG Y，LI C，HAN J，et al. Mechanical behaviours of granite containing two flaws under uniaxial increasing‐amplitude fatigue loading conditions：An insight into fracture evolution analyses[J]. Fatigue and Fracture of Engineering Materials and Structures，2020，43(9)：2 055–2 070.
[9] WANG Y，LI C H，HAN J Q. On the effect of stress amplitude on fracture and energy evolution of pre-flawed granite under uniaxial increasing-amplitude fatigue loads[J]. Engineering Fracture Mechanics，2020，240，107366.
[10] WANG Y，HAN J Q，LI C H. Acoustic emission and CT investigation on fracture evolution of granite containing two flaws subjected to freeze-thaw and cyclic uniaxial increasing-amplitude loading conditions[J]. Construction and Building Materials，2020，260：119769.
[11] 郭修成. 单轴应力下的孔洞–裂隙扩展规律数值模拟[J]. 煤田地质与勘探，2020，48(2)：179–186.(GUO Xiucheng. Numerical simulation of propagation law of pore-fracture under uniaxial stress[J]. Coal Geology and Exploration，2020，48(2)：179–186.(in Chinese))
[12] 郑宏利. 饱水风干孔洞——裂隙岩石强度试验研究[J]. 江西建材，2020，(12)：10–11.(ZHENG Hongli. Experimental study on strength of granite specimens containing fissure-hole flaws after “Saturation-air dry” function[J]. Jiangxi Building Materials，2020，(12)：10–11.(in Chinese))
[13] CARTER B J，LAJTAI E Z，PETUKHOV A. Primary and remote fracture around underground cavities[J]. International Journal for Numerical and Analytical Methods in Geomechanics，1991，15(1)：21–40.
[14] 郝燕奎，聂 鑫. 孔洞–裂隙缺陷岩石力学及声发射特征分析[J]. 中国地质调查，2019，6(3)：63–67.(HAO Yankui，NIE Xin. Mechanics and acoustic emission characteristics analysis of fracture-cavity defective rock[J]. China Geological Survey，2019，6(3)：63–67.(in Chinese))
[15] 赵 凯，乔春生，罗富荣，等. 不同频率循环荷载下石灰岩疲劳特性试验研究[J]. 岩石力学与工程学报，2014，33(增2)：3 466–3 475. (ZHAO Kai，QIAO Chunsheng，LUO Furong，et al. Experimental study of fatigue characteristics of limestone samples subjected to uniaxial cyclic loading with different frequencies[J]. Chinese Journal of Rock Mechanics and Engineering，2014，33(Supp.2)：3 466–3 475.(in Chinese))
[16] FAKHIMI A，CARVALHO F，ISHIDA T，et al. Simulation of failure around a circular opening in rock[J]. International Journal of Rock Mechanics and Mining Sciences，2002，39：507–515.
[17] YANG S Q. Experimental study on deformation，peak strength and crack damage behavior of hollow sandstone under conventional triaxial compression[J]. Engineering Geology，2016，213：11–24.
[18] 卢高明，李元辉，张希巍，等. 周期荷载作用下黄砂岩疲劳破坏变形特性试验研究[J]. 岩土工程学报，2015，37(10)：1 886–1 892.(LU Gaoming，LI Yuanhui，ZHANG Xiwei，et al. Fatigue deformation characteristics of yellow sandstone under cyclic loading[J]. Chinese Journal of Geotechnical Engineering，2015，37(10)：1 886–1 892. (in Chinese))
[19] 李庶林，周梦婧，高真平，等. 增量循环加卸载下岩石峰值强度前声发射特性试验研究[J]. 岩石力学与工程学报，2019，38(4)：724–735.(LI Shulin，ZHOU Mengjing，GAO Zhenping，et al. Experimental study on acoustic emission characteristics before the peak strength of rocks under incrementally cyclic loading-unloading methods[J]. Chinese Journal of Rock Mechanics and Engineering，2019，38(4)：724–735.(in Chinese))
[20] 纪洪广，卢 翔. 常规三轴压缩下花岗岩声发射特征及其主破裂前兆信息研究[J]. 岩石力学与工程学报，2015，34(4)：694–702.(JI Hongguang，LU Xiang. Characteristics of acoustic emission and rock fracture precursors of granite under conventional triaxial compression[J]. Chinese Journal of Rock Mechanics and Engineering，2015，34(4)：694–702.(in Chinese))
[21] 朱振飞，陈国庆，肖宏跃，等. 基于声发射多参量分析的岩桥裂纹扩展研究[J]. 岩石力学与工程学报，2018，37(4)：909–918.(ZHU Zhenfei，CHEN Guoqing，XIAO Hongyue，et al. Study on crack propagation of rock bridge based on multi parameters analysis of acoustic emission[J]. Chinese Journal of Rock Mechanics and Engineering，2018，37(4)：909–918.(in Chinese))
[22] SONG R，BAI Y M，ZHANG J P，et al. Experimental investigation of the fatigue properties of salt rock[J]. International Journal of Rock Mechanics and Mining Sciences，2013，1997，64(1)：68–72.
[23] WANG Y，LIU D，HAN J，et al. Effect of fatigue loading-confining stress unloading rate on marble mechanical behaviors：an insight into fracture evolution analyses[J]. Journal of Rock Mechanics and Geotechnical Engineering，2020，12(6)：1 249–1 262.
[24] REN S，BAI Y M，ZHANG J P，et al. Experimental investigation of the fatigue properties of salt rock[J]. International Journal of Rock Mechanics and Mining Sciences，2013，64：68–72.
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2022, Vol. 41 
