Article
Construction & Building Technology
Yun Zhou, Yajing Yan, Kang Zhao, Xiang Yu, Yufeng Song, Junqiang Wang, Tianyuan Suo
Summary: This study investigated the relationship between damage variables and fractal dimensions during deformation and destruction of tantalum-niobium tailing cemented paste backfill (CPB). It was found that the fractal dimensions of the CPB gradually decreased while the damage variables increased during deformation and destruction, with the stages of reduction in fractal dimensions corresponding to the stages of increase in damage variables. The fractal dimensions tended to converge to a certain value before deformation and failure of the CPB, and this convergence was different under different loading modes. Additionally, the fractal dimensions approaching a certain value were identified as a precursor to the overall macroscopic destruction of the CPB.
CONSTRUCTION AND BUILDING MATERIALS
(2021)
Article
Engineering, Multidisciplinary
Ran Zhang, Jie Liu, Zhanyou Sa, Zaiquan Wang, Shouqing Lu, Zhaoyang Lv
Summary: This study focuses on the deformation characteristics and precursory information of coal and rock under true triaxial loading conditions. The experiments demonstrate the impact of gas pressure and confining stress on the deformation, failure, and fractal characteristics of coal. The dynamic changes in correlation dimension accurately reflect the damage evolution process of coal samples, providing valuable insights for preventing coal and rock gas dynamic disasters and reducing casualties and property loss in coal mines.
Article
Construction & Building Technology
Jian Yang, Kang Zhao, Xiang Yu, Yajing Yan, Zhiwei He, Yun Zhou, Yanming Lai
Summary: The fracture evolution characteristics of fiber-reinforced backfill were explored through the analysis of amplitude correlation dimension, RA correlation dimension, and time of acoustic emission. The study found that the fiber-reinforced backfill exhibits good fractal characteristics, with the amplitude time series showing better fractal properties compared to the RA time series.
CEMENT & CONCRETE COMPOSITES
(2022)
Article
Materials Science, Composites
Yi-Er Guo, De-Guang Shang, Lin-Xuan Zuo, Lin-Feng Qu, Geng Hou, Di Cai, Tian Jin, Xiang Yin
Summary: This study investigates the fatigue damage modes of carbon fiber/epoxy composite laminates with symmetrical architecture under fully reversed loading using acoustic emission (AE) technique. Principal component analysis and K-means cluster analysis are performed to identify different damage modes based on AE characteristic parameters, including energy, amplitude, and duration time. The analysis results reveal that high-intensity AE signals are generated by compressive load, while low-intensity AE signals are generated by tensile load. The fatigue damage caused by compressive load is found to be greater than that of tensile load. Additionally, the laminate specimens are classified into five types of damage modes, including matrix cracks, fiber/epoxy interface debonding, shear, delamination, and fiber breakage.
POLYMER COMPOSITES
(2022)
Article
Mining & Mineral Processing
Jinjing Zuo, Renshu Yang, Min Gong, Xinmin Ma, Yanbing Wang
Summary: This study conducted a blasting experiment on iron ore samples and analyzed the resulting fracture characteristics. The decoupling coefficient was found to significantly affect the fracture modes and degree of damage.
INTERNATIONAL JOURNAL OF MINING SCIENCE AND TECHNOLOGY
(2022)
Article
Mining & Mineral Processing
Zhen Huang, Qixiong Gu, Yufan Wu, Yun Wu, Shijie Li, Kui Zhao, Rui Zhang
Summary: This study investigated the failure characteristics of sandstone under different confining pressures using AE tests. The results showed that the activity of the AE signal is strongly related to the confining pressure, and the evolution of the Ib value can be divided into fluctuation, stability, and decrease stages.
INTERNATIONAL JOURNAL OF MINING SCIENCE AND TECHNOLOGY
(2021)
Article
Materials Science, Characterization & Testing
Kang Zhao, Qizheng Huang, Yun Zhou, Yajing Yan, Jian Yang, Chao Ma, Qiang Nie, Jiale Chen, Yichen Shi
Summary: This study conducted uniaxial compression and simultaneous acoustic emission (AE) tests on cement superfine tailings backfill (CSTB) with different degrees of internal initial defects. The results showed that doping with a doping agent (DA) significantly enhanced the fluctuation and jump of the CSTB b-value, with two jumps observed in the loading process. The fractal characteristics of CSTB with DA doping were improved, and both the fractal dimension and the b-value showed a rapid decreasing trend before the overall unstable failure occurred. The admixture of DA increased the number of initial defects and non-homogeneity within the CSTB, resulting in somewhat random generation of 3D localization points of AE events. These findings can help better analyze the unstable failure process of backfill in mine hollow areas and carry out appropriate support work.
NONDESTRUCTIVE TESTING AND EVALUATION
(2023)
Article
Geosciences, Multidisciplinary
Qi Zhang, Xiangchun Li, Jiaxing Gao, Suye Jia, Xinwei Ye
Summary: The macro- and meso-damage evolution characteristics of different types of coal were studied using acoustic emission (AE) experiments and microscopy methods. The results showed that AE signals were mainly generated during the unstable fracture propagation stage under compression and were closely related to the evolution of cracks and defects. The macro-damage modes of different types of coal also varied.
NATURAL RESOURCES RESEARCH
(2022)
Article
Engineering, Geological
Yanan Gao, Donghao Lan, Shengqi Yang, Peng Hou, Yunlong Wang, Feng Ding
Summary: A series of mechanical tests and acoustic emission (AE) monitoring were conducted to investigate the effects of disturbance stress paths, disturbance modes, and initial confining pressures (ICPs) on the behavior of engineering rocks. The fractal dimensions of AE temporal distribution (Dt) and spatial distribution (Ds) were calculated and analyzed, along with the normalized AE count. The results showed that the different disturbance modes had sensitive, inferior sensitive, and delayed sensitive effects on the AE activities, depending on the ICP. The damage severity of the disturbance modes followed the order of HD, MD, and LD modes under an ICP of 12.5 MPa. The changes in Dt and Ds were consistent with the sensitive effect. Under an ICP of 25 MPa, only the HD mode caused significant damage, while the LD and MD modes showed inferior sensitive effects. Similarly, under an ICP of 37.5 MPa, the late-period Ds showed significant differences among the three disturbance modes, indicating delayed sensitive effects. Overall, the study revealed that the damage propagation and mechanical behavior of engineering rocks were influenced by both the ICP and disturbance mode.
ROCK MECHANICS AND ROCK ENGINEERING
(2023)
Article
Construction & Building Technology
Jingxian Xu, Xue Luo, Xin Qiu, Ganghua Hu
Summary: The objective of this study was to diagnose the damage behavior of asphalt mixtures using acoustic emission (AE) as the real-time monitoring technique. The study found that the time and frequency characteristics of AE signals can reveal the damage state of asphalt mixtures, and proposed an index RBD to evaluate the degree of damage.
CONSTRUCTION AND BUILDING MATERIALS
(2022)
Article
Engineering, Mechanical
Kui Zhao, Xing Wang, Li Wang, Peng Zeng, Daoxue Yang, Jiefang Jin
Summary: This study investigates the influence of water on the crack and acoustic emission (AE) behavior evolution of red sandstone specimens during deformation and failure. Uniaxial compression tests were conducted under different water contents. The results show that the peak strength of red sandstone decreases with increasing water content, and the dominant failure pattern changes from tension to shear. The AE events rate can be used as a precursor for the instability and failure of rock specimens with different water contents.
THEORETICAL AND APPLIED FRACTURE MECHANICS
(2022)
Article
Mechanics
Xiao Wang, Jie Xu, Qingrui Yue, Xiaogang Liu
Summary: The application of advanced acoustic emission signal analysis techniques can aid in the identification of fracture damage modes in ductile materials and provide fracture precursor warnings. This study used G20Mn5QT cast steel material fracture acoustic emission monitoring tests under different constraints as an example. Principal component analysis and k-means++ were used to select acoustic emission feature parameters and cluster damage modes. Several fracture precursor warning indicators and influencing factors were analyzed and compared. The findings show the presence of shear and tensile fracture damage modes in type-I fracture tests, with tensile fracture modes dominating. Fractal dimensions, b-values, and Ib-values show a strong correlation with the fracture damage evolution process. Natural time analysis can provide quantitative fracture precursor warnings, but the sliding window length affects the absolute value sizes inversely.
ENGINEERING FRACTURE MECHANICS
(2023)
Article
Engineering, Mechanical
Hang Li, Hongling Ma, Chunhe Yang, Kai Zhao, Zhiwen Hu, J. J. K. Daemen
Summary: This study conducted cyclic loading experiments on impure Huai'an rock salt and monitored acoustic emissions in real-time. The results showed that as the loading stress increased, the cumulative acoustic emission energy increased stepwise, with a band pattern of low, medium, and high frequencies. The proportion of high-frequency signals decreased while that of low-frequency signals increased. The constant lower limit stress caused higher cumulative acoustic emission energy and amplitude, and smaller b-values for the salt samples, indicating increased cracks and damage. The primary mode of failure for rock salt under cyclic loading was found to be tensile cracking, with shear cracks promoted by the constant lower limit stress.
INTERNATIONAL JOURNAL OF FATIGUE
(2023)
Article
Construction & Building Technology
Zhiwei He, Kang Zhao, Yajing Yan, Fujin Ning, Yun Zhou, Yufeng Song
Summary: The study investigated the failure law of a cement paste backfill (CPB) and rock combination under pressure with different cement tailings ratios, finding significant influence of tailings content on crack evolution and acoustic emission characteristics at different stages of the CPB.
CONSTRUCTION AND BUILDING MATERIALS
(2021)
Article
Engineering, Environmental
Linqi Huang, Yide Guo, Xibing Li
Summary: This study investigates the effect of high-temperature environment on shale failure characteristics through uniaxial compression tests and acoustic emission monitoring. The results show that shale specimens in both horizontal and perpendicular bedding directions experienced severe rockburst failure. The temperature had a significant effect on the rockburst characteristics of the specimens in both bedding directions.
BULLETIN OF ENGINEERING GEOLOGY AND THE ENVIRONMENT
(2022)
Article
Geochemistry & Geophysics
Hongfei Li, Lingzhi Xie, Li Ren, Bo He, Yang Liu, Jun Liu
Summary: The study systematically investigated the fracture properties of sandstone in CO2 sequestration simulations, revealing that immersion in CO2 solution and pure water can increase the porosity of sandstone and decrease its mechanical properties. These findings are significant for understanding the dissolution processes during CO2 sequestration and their impact on sandstone fracture properties, providing theoretical guidance for CO2 storage in the Xujiahe Formation in the Sichuan Basin.
Article
Engineering, Geological
Ersheng Zha, Zetian Zhang, Ru Zhang, Shiyong Wu, Cunbao Li, Li Ren, Mingzhong Gao, Jifang Zhou
Summary: This study systematically proposed a laboratory simulation method to test the stability of deep caverns after excavation disturbance, revealing a significant decrease in long-term rock strength considering excavation disturbance. The results also showed that with an increase in stress level, the transient strain of the deep rock increases nearly linearly, while the axial creep strain rate increases exponentially, with distinctive characteristics observed in different stages through AE monitoring.
INTERNATIONAL JOURNAL OF ROCK MECHANICS AND MINING SCIENCES
(2021)
Article
Engineering, Civil
R. Zhang, H. P. Xie, L. Ren, J. H. Deng, M. Z. Gao, G. Feng, Z. T. Zhang, X. P. Li, Q. Tan
Summary: The deeper the burial depth, the more severe the rock damage and the more complex the fracture network caused by excavation-induced deterioration. At shallow depths, an excavation-damaged zone and excavation-disturbed zone were found, while at greater depths, a highly damaged zone and excavation-disturbed zone were observed. The formation of excavation-damaged zones at deep depths follows a stress-concentration-controlled mode, while a pure unloading-controlled mode is observed at very shallow depths.
ARCHIVES OF CIVIL AND MECHANICAL ENGINEERING
(2022)
Article
Geochemistry & Geophysics
Anlin Zhang, Tao Feng, Liangwen Jiang, Dong Wang, Zhewei Wang, Ru Zhang, Gan Feng, Zhilong Zhang, Jianhui Deng, Li Ren
Summary: The study investigates the mechanical behaviors and micro-cracking behaviors of deep slate under different stress environments through triaxial loadings. The results indicate that confining pressure increases the strength, elastic modulus, Poisson's ratio, and crack characteristic stresses of the studied slate. The study also identifies slate failure precursors through acoustic emission (AE) analysis and observes a transition of the failure pattern from compressive shear to tensile shear with an increase in confining pressure.
Article
Metallurgy & Metallurgical Engineering
Fan Zi-dong, Xie He-ping, Ren Li, Zhang Ru, He Rui, Li Cun-bao, Zhang Ze-tian, Wang Jun, Xie Jing
Summary: Shear-sliding mode (mode II) fracture of rocks is an important failure form in deep underground engineering. This study conducted direct shear tests on a typical shale to investigate the anisotropic shear fracture behaviors under high normal stress conditions. The results show significant 3D anisotropy in mode II fracture toughness (K-IIc), while the anisotropy in the critical mode II energy release rate (G(IIc)) is not as significant. Additionally, the anisotropy in the prepeak input energy is consistent with that in G(IIc), which is a new finding.
JOURNAL OF CENTRAL SOUTH UNIVERSITY
(2022)
Article
Energy & Fuels
Rui He, Li Ren, Ru Zhang, Zheming Zhu, Xin Sun
Summary: This study investigates the mechanical properties of shale, revealing its anisotropic behavior when measured in different directions. By conducting experiments, the elastic parameters of shale are accurately determined, and it is found that shale rapidly releases energy after experiencing crack damage stress.
Article
Engineering, Geological
Fengqiang Gong, Wuxing Wu, Li Ren
Summary: By combining rock drilling unloading devices and triaxial systems, the influence of unloading effect of a circular tunnel face on rockburst process was investigated. Experimental tests were conducted on intact cubic red sandstone samples to simulate strain rockburst under high initial stress and internal unloading. It was found that internal unloading affects sidewall failure, causing strength-weakening effect which becomes more significant with an increase in buried depth.
JOURNAL OF ROCK MECHANICS AND GEOTECHNICAL ENGINEERING
(2023)
Article
Engineering, Geological
Kun Xiao, Ru Zhang, Jing Xie, Li Ren, Mingzhong Gao, Zetian Zhang, Chendi Lou, Ting Ai, Ersheng Zha
Summary: This study investigates the impact of fracture characteristics on the mechanical and hydraulic properties of rock mass. By simplifying fractures as non-similar ellipses, a multifactor coupling stereological relationship of the sampling trace length distribution is established. The distribution expressions of the major axis and axial ratio of the elliptical fractures are obtained, and a method is proposed to solve the probability density function of the characteristic size of the elliptical fractures. The applicability of the proposed method is verified through a Monte Carlo statistical simulation.
ROCK MECHANICS AND ROCK ENGINEERING
(2023)
Article
Engineering, Geological
Q. Zhou, H. P. Xie, Z. M. Zhu, R. He, H. J. Lu, Z. D. Fan, X. F. Nie, L. Ren
Summary: Insight into the anisotropic fracture properties of shale under high in situ stress is given through a series of hydraulic fracturing tests on double wing crack specimens of Longmaxi shale. The study finds that the fracture resistance of shale significantly increases with confining pressure, and both fracture toughness and fracture energy exhibit remarkable anisotropies. The study also highlights the influence of in situ stress on shale fracture anisotropy, which should be carefully considered in hydraulic fracturing design.
ROCK MECHANICS AND ROCK ENGINEERING
(2023)
Article
Chemistry, Physical
Xiaofang Nie, Zidong Fan, Qin Zhou, Zilong Yao, Zheming Zhu, Li Ren
Summary: The mechanical properties of shale are influenced by in situ geological conditions, but the understanding of this influence is still immature. This paper investigates the elasticity and characteristic stress thresholds of shales with differently oriented bedding planes under deep in situ geological conditions. Experimental results show that depth and bedding plane orientation have different effects on the mechanical properties of shale.
Article
Energy & Fuels
Zi-Dong Fan, Li Ren, He -Ping Xie, Ru Zhang, Cun-Bao Li, Hui-Jun Lu, An -Lin Zhang, Qin Zhou, Wei-Qiang Ling
Summary: This study investigates the shear failure anisotropy of Longmaxi shale in 3D space through direct shear tests combined with acoustic emission (AE) and digital image correlation (DIC) techniques. X-ray computed tomography (CT) scanning is employed for detailed analysis of fracture development. The results reveal 3D anisotropies in shear strength parameters, with the arrester orientation exhibiting different shear strength parameters compared to the shale matrix. Four characteristic stress levels are identified to capture the progressive shear failure process, with shear damage-induced dilation observed at crack initiation and coalesce stress thresholds. The dominated microcracking mechanism shifts from tensile-mode to shear-mode during crack coalescence, with more tensile-mode AE events generated in samples with arrester and divider orientations.
Article
Engineering, Geological
Wenzhuo Cao, Ru Zhang, Xiaofang Nie, Li Ren
Summary: Investigation into the role of stress paths on fracture slip behavior and seismic response is crucial for understanding causal mechanisms for induced seismicity. The experiments in this study simulated slippage along a pre-existing fracture under different fluid injection-related stress and pressure paths. The results showed that fracture effective normal stress relaxation tends to promote slip acceleration, while shear stress increase causes larger seismic moment than effective normal stress relaxation paths.
ROCK MECHANICS AND ROCK ENGINEERING
(2023)
Article
Chemistry, Physical
Zilong Yao, Zidong Fan, Qin Zhou, Xiaofang Nie, Li Ren
Summary: The fracture toughness of shale plays a crucial role in hydraulic fracturing design and optimization. This study investigates the influences of crack length, hole size, and elastic parameter anisotropy on the shape factor (f) for different bedding orientations using finite element simulation. The results reveal that the mode I shape factor increases with increasing hole size, and the influence of crack length on f depends on hole sizes. Anisotropy in f is observed under different bedding orientations. The degree of anisotropy in Young's modulus significantly affects f and is associated with the bedding orientation of the specimen. The apparent shear modulus ratio has relatively little impact on f. Hydraulic fracturing experiments on Longmaxi shale specimens with different bedding orientations confirm the numerical calculations, with the peak pressure and fracture toughness being lowest in the short-transverse direction and highest in the arrester direction.
Article
Thermodynamics
Dong Wang, Xin-Zhong Wang, Guang-Ze Zhang, Zheng-Xuan Xu, Zhi-Jun Liu, Tao Feng, Ru Zhang, Zhi-Long Zhang, Gan Feng, Li Ren
Summary: The characteristics of energy evolution in rock deformation and failure were studied through thermal mechanical coupling tests. A comprehensive evaluation index was proposed to examine the influence of temperature on rock strength and deformation ability from the perspective of elastic energy accumulation. Temperature has a varying negative effect on the strength and elastic modulus of rock samples at different temperature ranges.