Article
Engineering, Geological
Tian Yang Guo, Louis Ngai Yuen Wong, Zhijun Wu
Summary: This study investigates the effect of thermal treatment on the microcracking behavior of granite, identifying a transition phenomenon in microcracking behavior as the thermal treatment temperature increases. Through analysis of acoustic emissions and fracture process zone (FPZ) development features, it is found that the development of FPZ exhibits different characteristics as the temperature rises.
ENGINEERING GEOLOGY
(2021)
Article
Engineering, Mechanical
Xudong Chen, Jianhui Tang, Nan Zhang, Feng Dai, Mingdong Wei
Summary: This study comprehensively presents the fracture behavior of cracked rocks subjected to prepeak and postpeak cyclic loads. The experiments revealed that in prepeak loading-unloading cycles, deformation of the specimen gradually developed from elastic to elastic-plastic, with tension-dominated microcracking. In postpeak cycles, parameters such as horizontal strain and crack length generally increased cumulatively with the cycle number but locally decreased with unloading, while microcracks were still produced during unloading and shear-type AE signals increased.
FATIGUE & FRACTURE OF ENGINEERING MATERIALS & STRUCTURES
(2022)
Article
Engineering, Geological
Hua Li, Fei Wang, Fei Chen, Jianhui Deng, Siyuan Zhao
Summary: An experimental and theoretical study on high-frequency emission waves due to rock fracture in tension and shear is conducted. An improved AE-signal processing method is proposed to identify the exact high-frequency radiation in a rupture event. The findings suggest that shear cracking generates more high-frequency components and tends to radiate energy in the form of waves with larger RA values.
INTERNATIONAL JOURNAL OF ROCK MECHANICS AND MINING SCIENCES
(2023)
Article
Engineering, Geological
Tian Yang Guo, Louis Ngai Yuen Wong
Summary: Research shows that under mixed-mode I-II loading conditions, the initiation angles of macrocracks in granite are less influenced compared to more homogeneous materials like PMMA. Acoustic emissions monitoring reveals that microcracks under mixed-mode I-II loading conditions do not nucleate as easily as under mode I loading. Additionally, the presence of mode II loading alters the acoustic emissions source mechanisms, affecting the unstable propagation of macrocracks.
INTERNATIONAL JOURNAL OF ROCK MECHANICS AND MINING SCIENCES
(2021)
Article
Engineering, Mechanical
Nan Zhang, Ahmadreza Hedayat, Hector Gelber Bolanos Sosa, Roberto Pedro Huamani Bernal, Nestor Tupa, Isaac Yanqui Morales, Reynaldo Sabino Canahua Loza
Summary: Sustainably reusing mine tailings and reducing the economic costs of storing them is a critical concern in geomechanics. This paper investigates the fracture behaviors of geopolymer made from mine tailings, highlighting the importance of understanding fracture toughness and notch depth sensitivity in geopolymer specimens. The study fills a knowledge gap in the field and provides insights into the fracture behaviors of geopolymer under different loading conditions.
THEORETICAL AND APPLIED FRACTURE MECHANICS
(2021)
Article
Mechanics
Xiaoran Wang, Enyuan Wang, Xiaofei Liu, Xin Zhou
Summary: The study investigated the mechanical and temporal-spatial microcracking behaviors of fractured sandstones under different loading rates using acoustic emission monitoring. The results showed significant static loading rate effects on the mechanical, acoustic, and microcracking processes. Increasing loading rates led to a change in dominant failure modes of fractured sandstones.
ENGINEERING FRACTURE MECHANICS
(2021)
Article
Engineering, Mechanical
Weimin Song, Zicheng Deng, Hao Wu, Zihao Xu
Summary: This study conducted I-II mixed mode fracture tests using cohesive zone modeling technique under -10 degrees C. It was found that increasing the notch angle increased the peak load and the contribution of mode II fracture on the overall fracture resistance, while the influence of loading rate was minimal.
THEORETICAL AND APPLIED FRACTURE MECHANICS
(2023)
Article
Engineering, Mechanical
Arsalan Ajdani, Majid R. Ayatollahi, Lucas F. M. da Silva
Summary: An improved SCB specimen is introduced for obtaining the mixed mode fracture envelope of a ductile adhesive with a significant fracture process zone ahead of the crack tip. The proposed test procedure is simple and does not require special loading fixtures, covering the whole range of mixed-mode ratios. Experimental results show that crack growth does not affect the mixed-mode ratio of the adhesive joint.
THEORETICAL AND APPLIED FRACTURE MECHANICS
(2021)
Article
Polymer Science
Yuki Ogawa, Kimiyoshi Naito, Keisuke Harada, Hiroyuki Oguma
Summary: This study compared and analyzed the critical separation energy of three SGA adhesives, as well as examined the mechanical properties of the bond. It was found that the highly ductile adhesive showed plastic deformation in the steel adherends during the loading-unloading test, while the high tensile strength and modulus adhesives experienced a sudden decrease in load without plastic deformation. The critical separation energy increased with increasing adhesive thickness, and the highly ductile adhesives were more affected by adhesive thickness than highly strength adhesives.
Article
Engineering, Mechanical
Xiling Liu, Yuan Zeng, Changgen Xia, Huini Liu, Qin Xie, Yuchen Zhong
Summary: Understanding the fracture characteristics and size effect of rocks is crucial for predicting the behavior of rock masses and designing underground structures. In this study, three-point bending fracture experiments were conducted on specimens of different sizes, and the fracture characteristics were analyzed using DIC and AE technologies. The results showed that the Fracture process zone (FPZ) length and fracture toughness of granite are size-dependent parameters, with the FPZ length growth rate increasing with increasing load level. Tensile failure was the dominant failure mode during fracture, and the proportion of tensile failure increased with specimen size. The temporal b value, average AF value, and RA value showed corresponding stage changes with time, with the minimum b value, minimum AF value, and maximum RA value characterizing the maximum macroscopic growth rate.
THEORETICAL AND APPLIED FRACTURE MECHANICS
(2023)
Article
Mechanics
Shirui Zhang, Shili Qiu, Ping Li, Yongyuan Kou, Zhenkun Xie, Lexin Jia
Summary: The progressive fracture mechanism of heterogeneous granite was studied from a mesoscopic perspective using the fracture process zone (FPZ) model and the breakable grain-based model (bGBM). Good agreement was found between the numerical simulation and laboratory tests in terms of load-displacement curves and crack propagation paths. The mesoheterogeneity of granite resulted in a nearly upright macroscopic fracture surface with local roughness and zigzag. The length of the slit had a significant effect on the damage distribution range of the semi-circular bending (SCB) specimen, and the peak load and mode I fracture toughness decreased with increasing slit length and supporting span. The accurate measurement of mode I fracture toughness of SCB specimens required consideration of the FPZ, with an average increment of 39% and 41% under different slit length and supporting span conditions.
ENGINEERING FRACTURE MECHANICS
(2023)
Article
Materials Science, Ceramics
Qinghua Han, An Wang, Weixin Wang, Jinrui Zhang
Summary: This research uses molybdenum tailings (MT) to strengthen fly ash-based geopolymers. The effect of MT on the fracture properties and damage behavior of the geopolymers was investigated through semi-circular bending (SCB) tests. Acoustic emission (AE) technology, digital image correlation (DIC) technology, and scanning electron microscopy (SEM) were used to evaluate the damage and strain behavior of the specimens during the fracture process. The results show that the addition of MT significantly increases the tensile strength, fracture toughness, and fracture energy of the fly ash-based geopolymers, with peak values reached at 30 wt% MT contents.
CERAMICS INTERNATIONAL
(2023)
Article
Engineering, Mechanical
Jinyin Ma, Diyuan Li, Quanqi Zhu, Meng Liu, Qianrong Wan
Summary: Through a series of experiments, it was found that the Mode I fatigue fracture behavior of hard rock is significantly affected by dynamic disturbance, with the nonlinearity degree p increasing with increasing pre-static load levels, and the disturbance frequency having a significant impact on corrected fracture toughness.
THEORETICAL AND APPLIED FRACTURE MECHANICS
(2022)
Article
Mechanics
Jia-Le Li, Xin-Dong Wei, Gao-Feng Zhao
Summary: This study combines a semi-circular bend test with a small-scale direct tension test to determine the KIc and FPZ length of rocks of different sizes, and explores the mechanism of the size effect on the KIc. It is found that the size effect is mainly controlled by the softening zone size of the mesoscale grain bond, rather than other mechanical parameters of rocks. By introducing a softening model, the change in KIc values and FPZ length of rocks of different sizes is successfully reproduced.
ENGINEERING FRACTURE MECHANICS
(2023)
Article
Engineering, Mechanical
Yingtao Si, Jianpo Liu, Fengtian Li, Hongxu Shi, Guangliang Yan, Jiancun Song, Changyin Zhang
Summary: This study investigates the relationship between the fracture pattern of underground metal mine roadways and static-blast loading using theoretical analysis and experimentation. The results show that the macroscopic cracks around the roadway are mainly attributed to the combined action of static loading and blast-induced disturbances, with static stress loading causing more severe damage than blast-induced disturbances. To control the progressive fracture of rock surrounding the roadway, it is necessary to strengthen the support for the high-stress area and the blast-facing side.
ENGINEERING FAILURE ANALYSIS
(2023)
Article
Mechanics
Louis Ngai Yuen Wong, Tian Yang Guo
ENGINEERING FRACTURE MECHANICS
(2019)
Article
Engineering, Geological
Wei Wei, Qi Zhao, Qinghui Jiang, Giovanni Grasselli
ROCK MECHANICS AND ROCK ENGINEERING
(2020)
Article
Engineering, Geological
Louis Ngai Yuen Wong, Fanzhen Meng, Tianyang Guo, Xiangchao Shi
ROCK MECHANICS AND ROCK ENGINEERING
(2020)
Article
Geosciences, Multidisciplinary
Qi Zhao, Steven D. Glaser, Nicola Tisato, Giovanni Grasselli
GEOPHYSICAL RESEARCH LETTERS
(2020)
Article
Engineering, Geological
Qi Zhao, Steven D. Glaser
ROCK MECHANICS AND ROCK ENGINEERING
(2020)
Article
Engineering, Geological
Tian Yang Guo, Louis Ngai Yuen Wong
ENGINEERING GEOLOGY
(2020)
Article
Engineering, Geological
Tian Yang Guo, Louis Ngai Yuen Wong, Zhijun Wu
Summary: This study investigates the effect of thermal treatment on the microcracking behavior of granite, identifying a transition phenomenon in microcracking behavior as the thermal treatment temperature increases. Through analysis of acoustic emissions and fracture process zone (FPZ) development features, it is found that the development of FPZ exhibits different characteristics as the temperature rises.
ENGINEERING GEOLOGY
(2021)
Article
Computer Science, Interdisciplinary Applications
Yuan Chen, Gang Ma, Wei Zhou, Deheng Wei, Qi Zhao, Yuxiong Zou, Giovanni Grasselli
Summary: By combining X-ray micro-CT and hybrid finite-discrete element method, this study investigates the mechanical behaviors of granular materials. The research reveals that granular materials deform plastically through spatially localized zones, which control the macroscopic responses of the system. The proposed tool provides insights into bridging length scales from particle to granular system.
COMPUTERS AND GEOTECHNICS
(2021)
Article
Engineering, Geological
Tian Yang Guo, Louis Ngai Yuen Wong
Summary: Research shows that under mixed-mode I-II loading conditions, the initiation angles of macrocracks in granite are less influenced compared to more homogeneous materials like PMMA. Acoustic emissions monitoring reveals that microcracks under mixed-mode I-II loading conditions do not nucleate as easily as under mode I loading. Additionally, the presence of mode II loading alters the acoustic emissions source mechanisms, affecting the unstable propagation of macrocracks.
INTERNATIONAL JOURNAL OF ROCK MECHANICS AND MINING SCIENCES
(2021)
Article
Engineering, Geological
Louis Ngai Yuen Wong, Tian Yang Guo, Zhijun Wu, Xinyu Xiao
Summary: The study investigates the influence of thermal microcracks on the microcrack damage of granite under impact loading, finding that thermal microcracks aggravate microcrack damage but have little effect on the proportions and energy distributions of AE event types. The microcracking mechanisms are related to the presence of thermal microcracks, with different temporal evolution features of event-type ratios observed in specimens with few thermal microcracks compared to those with substantial thermal microcracks.
ENGINEERING GEOLOGY
(2021)
Article
Construction & Building Technology
Guoqing Chen, Tian Yang Guo, Mehdi Serati, Bencan Pei
Summary: In this study, we experimentally investigate the effects of cyclic freeze-thaw (F-T) on the microcracking behaviour of sandstone under mode I loading. The results show that the cyclic F-T treatments inhibit the microcracking activities of the sandstone until the cycle number exceeds a certain threshold, beyond which the damage degree significantly increases.
CONSTRUCTION AND BUILDING MATERIALS
(2022)
Article
Engineering, Geological
Louis Ngai Yuen Wong, Xin Cui, Yahui Zhang, Zhijun Wu, Tianyang Guo
Summary: By conducting triaxial compression tests on Sichuan marble under 25-200 degrees Celsius, a clear trend of strength increase with temperature was observed, justifying the existence of thermal strengthening. The main reason leading to this phenomenon was inferred to be thermal expansion, resulting in tighter compaction between mineral grains. This study sheds light on the thermal effect on rock strength, providing valuable insights for rock engineering design.
ROCK MECHANICS AND ROCK ENGINEERING
(2022)
Article
Geochemistry & Geophysics
Fanzhen Meng, Louis Ngai Yuen Wong, Tianyang Guo
Summary: Rough fault surfaces play a dominant role in determining the mode of sliding. Stick-slip behavior occurs on all rough fractures during sliding, with stress drops and fault gouges increasing with normal stress. Micro-damage on post-shear surfaces includes powder-sized gouge, micro-cracks, and grain edge wear, increasing with normal stress. Different fault types have little discernible effect on stress drop. The study contributes to understanding the mechanics of dynamic geohazards associated with shear failure on rough faults or fracture surfaces.
