Article
Engineering, Geological
Wei Zeng, Yong-Fu Ye, Ze-Min Kuang, Wen-Ling Tian
Summary: In this study, a three-dimensional joint model is constructed using computed tomography scanning and digital image processing techniques. The model is integrated into a particle flow code to simulate triaxial compression tests under varying confining pressures. The results demonstrate the significant influence of rock fractures on the mechanical properties of rock masses, with the linear phase of the stress-strain curve being more pronounced at higher confining pressures.
INTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS
(2022)
Article
Computer Science, Interdisciplinary Applications
Ri-hong Cao, Rubing Yao, Hang Lin, Qi-bin Lin, Qingbing Meng, Tianbin Li
Summary: This paper investigates the shear failure behavior of 3D nonpersistent jointed rock masses through laboratory tests and numerical simulations. The results show that the shear strength, cohesion, and friction angle decrease with increasing joint persistence. A 3D DEM model with nonpersistent joints is established and the numerical results are consistent with the laboratory results. The crack initiation, propagation, and coalescence on the joint specimens are analyzed at the microscale.
COMPUTERS AND GEOTECHNICS
(2022)
Article
Materials Science, Multidisciplinary
Ke Zhang, Kai Zhang, Wenlian Liu, Jianbin Xie
Summary: This article discusses the challenging problem of crack identification in brittle rocks in rock mechanics. Sand-based 3D-printed specimens were used to represent jointed rock masses, and digital image correlation was employed for deformation measurement. The study proposes a covariance matrix-based measure to quantify the dispersion of strain data and identifies different crack types based on strain dispersion variation. A new crack identification criterion is suggested based on the rates of mutation for tensile and shear cracks.
MATERIALS & DESIGN
(2023)
Article
Physics, Multidisciplinary
Long Yan, Zhipeng Xiang, Weiya Xu, Rubin Wang, Hua Ji
Summary: The deformation, strength characteristics, and failure modes of irregular columnar jointed rock masses (CJRM) under uniaxial compression were investigated using numerical simulation. It was found that irregular CJRM exhibit significant anisotropy, with compressive strength varying in a typical U-shape curve with joint angle. The failure modes of irregular CJRM can be classified as splitting failure, shear-sliding failure along columnar joints, and combined failure of column fracturing and joint splitting. The study demonstrates the effectiveness and reliability of numerical simulation in investigating the mechanical properties and failure mechanism of irregular CJRM.
FRONTIERS IN PHYSICS
(2022)
Article
Mathematics
Yingjie Xia, Bingchen Liu, Tianjiao Li, Danchen Zhao, Ning Liu, Chun'an Tang, Jun Chen
Summary: This paper conducts numerical simulation tests using the finite element method to investigate the dynamic failure modes of irregular columnar jointed rock masses (CJRM) with different dip angles and the influence of stress wave parameters. The results show that the failure modes of CJRMs vary with different dip angles, and the change in stress wave parameters affects the development of rock mass failure.
Article
Geosciences, Multidisciplinary
Zhen Yang, Wancheng Zhu, Kai Guan, Baoxu Yan, Wenjun Luo, Peng Liang
Summary: Anchor technology is essential in geotechnical engineering to reinforce jointed rock masses. This study investigates the effects of anchorage and the three-dimensional crack propagation process through physical model tests and numerical simulations. The results show that anchorage improves the compressive performance and deformation capability of jointed rock masses, controlling crack propagation and restraining shear zone formation. The optimal anchor opportunity varies with joint angle.
FRONTIERS IN EARTH SCIENCE
(2022)
Article
Green & Sustainable Science & Technology
Baolin Xiong, Jia Sun, Yunmeng Zhao, Zhuangzhuang Wang, Zhiyuan Wang, Bo Chen
Summary: This study used digital image correlation method and acoustic emission equipment to observe the crack growth process in composite rock strata. The results showed that the strain field dispersion can be quantified using the covariance matrix parameter V, and the crack types can be identified based on the growth rate of V.
Article
Engineering, Civil
Xianghua Liu, Ke Zhang, Wenlian Liu, Jianbin Xie
Summary: This study investigates the reinforcement effect of weak inclusions on jointed rock masses containing an opening by preparing natural sandstone specimens with multiple non-persistent joints and an opening. Digital image correlation (DIC) is used to analyze the deformation fields and cracking mechanisms, and the results show that weak inclusions improve the mechanical properties of the rock. Four types of cracks are identified, and the influence of weak inclusions on cracking behavior is further clarified by analyzing fractal dimensions and strain data.
ARCHIVES OF CIVIL AND MECHANICAL ENGINEERING
(2022)
Article
Engineering, Multidisciplinary
Haiping Yuan, Lijun Xiong, Hengzhe Li, Hanbing Bian, Yixian Wang
Summary: In this study, a numerical computed tomography method is proposed based on numerical simulation, digital image processing, and three-dimensional reconstruction technology, which can effectively identify and reconstruct intrinsic damage in large-scale engineering rock mass. The method is validated and its applicability is demonstrated by applying it to the failure area of the Rm 417 tunnel.
Article
Engineering, Mechanical
Peng Li, Meifeng Cai, Yubing Gao, Mostafa Gorjian, Shengjun Miao, Yu Wang
Summary: Uniaxial compression tests were conducted on jointed granite samples with openings to investigate the macro/mesofracture and instability behaviors. The results showed that the peak strength and elastic modulus of the samples first decreased and then increased with increasing joint angle, reaching a minimum at around 45 degrees. The AE cumulative count before the peak stress was related to crack initiation or interpenetration, while the instantaneous increase in the AE count after the peak stress was associated with the stress drop caused by high strain localization or the formation of visible cracks. The accelerated release of AE energy can provide early warning for rock instability and failure. The existence of joints changed the stress distribution patterns and interacted with high stress concentration areas to dominate the fracturing process.
THEORETICAL AND APPLIED FRACTURE MECHANICS
(2022)
Article
Mechanics
Shuo Liu, Klaus Thoeni, Runhua Feng, Andrej Bona, Mohammad Sarmadivaleh
Summary: The study investigates the effect of heterogeneity on the propagation of fluid-driven fractures in hydraulic fracturing and proposes a novel finite element modelling framework for studying fracture propagation in heterogeneous ore deposits.
ENGINEERING FRACTURE MECHANICS
(2022)
Article
Computer Science, Interdisciplinary Applications
Lianheng Zhao, Nan Qiao, Dongliang Huang, Shi Zuo, Zijian Zhang
Summary: This study proposes a new technique for accurately analyzing the large-deformation failure mechanisms of soil-rock mixture slopes. The contours of natural rock blocks are obtained through digital image processing, and then analyzed and reconstructed using the discrete Fourier transform theory. Discrete models of soil-rock mixture slopes for MPM are constructed by combining the stochastic placement algorithm with digital image processing. The influences of the content, size, and morphology of rock blocks on the failure mechanisms of the slopes are investigated in detail.
COMPUTERS AND GEOTECHNICS
(2022)
Article
Ecology
Lang Song, Shaobo Chai, Jing Li, Boyang Song, Lianzeng Chai
Summary: Confining pressure plays a significant role in the strength and deformation characteristics of jointed rock mass. Understanding the mechanical and deformation characteristics of filled jointed rock under confining pressure is crucial for deep underground construction and geological disaster prevention. Experimental and numerical simulation results show that peak stress and strain increase with increasing confining pressure levels, and there is a strong linear relationship between peak stress and confining pressure level. The joint inclination angle also affects the peak and initiation stress of filled jointed rock. Confining pressure prolongs the development of micro-cracks in filled jointed rock, leading to a more dispersed distribution and increased total number of micro-cracks. The failure mode shifts from splitting to shear failure with increasing confining pressure levels. The change in joint inclination angle significantly influences the failure mode and micro-crack development characteristics of filled jointed rock.
FRONTIERS IN ECOLOGY AND EVOLUTION
(2023)
Article
Thermodynamics
Ahmed G. Almetwally, Hadi Jabbari
Summary: By utilizing 3D printed rock samples in experiments, the study reduced geometric uncertainties and accurately described pore network structures. This method showed potential in research on oil recovery.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2021)
Article
Engineering, Geological
Yudi Tang, Lei He, Wei Lu, Xin Huang, Hai Wei, Huaiguang Xiao
Summary: This paper proposes an algorithm for automatic extraction of rock fracture skeleton, mainly relying on the curvilinear structure enhancement filter Frangi. Through multiple image processing, the dark region contrast of rock surface images is enhanced while noise is reduced, improving the extraction effect.
INTERNATIONAL JOURNAL OF ROCK MECHANICS AND MINING SCIENCES
(2021)
Article
Thermodynamics
Jizhao Xu, Cheng Zhai, Pathegama Gamage Ranjith, Shuxun Sang, Yong Sun, Yuzhou Cong, Wei Tang, Yangfeng Zheng
Summary: The study investigated the effects of liquid CO2 on coal strength, finding that the coupled effects of liquid CO2 temperature and adsorption can influence coal fracture behavior and crack morphology.
Article
Energy & Fuels
Jizhao Xu, Cheng Zhai, P. G. Ranjith, Shuxun Sang, Xu Yu, Yong Sun, Yuzhou Cong, Yangfeng Zheng, Wei Tang
Summary: The study found that coal affected by liquid CO2 exhibited more complex destruction patterns, larger fractal dimensions, and greater structure degradation. The affected coals showed diverse mechanical responses, with temperature shock and CO2 adsorption potentially leading to crack growth and strength deterioration, ultimately destroying the coal with smaller yield strength.
Article
Energy & Fuels
David Lall, Vikram Vishal, M. V. Lall, P. G. Ranjith
Summary: The study found that gas production was less efficient in the presence of a permeable heterogeneity compared to other scenarios. The permeability affects the vertical extent of dissolved methane volume during thermal stimulation and huff and puff, while well depth influences the radial extent of dissociated molecules.
JOURNAL OF PETROLEUM SCIENCE AND ENGINEERING
(2022)
Article
Engineering, Geological
Chunlin Zhong, Zhenyu Zhang, P. G. Ranjith, Chengpeng Zhang, Kangsheng Xue
Summary: The study found that pore water can affect the radial and volumetric strain evolution of coal, leading to dilation deformation. Additionally, due to the water propping effect, the cracks in saturated coal cannot close tightly during loading, causing sliding and generating numerous tensile cracks. Loading frequency can impact the decay of pore pressure, consequently influencing the number of cracks in coal.
ROCK MECHANICS AND ROCK ENGINEERING
(2022)
Article
Energy & Fuels
Shashika Gajanayake, Ranjith Pathegama Gamage, Pabasara Wanniarachchige, Decheng Zhang
Summary: This study conducted molecular dynamic simulations to investigate the effects of temperature, pressure, and initial CO2 concentration on gas replacement characteristics for methane recovery and CO2 storage. The results showed that higher temperatures resulted in greater methane recovery, but diminished CO2 storage capacity. Higher initial CO2 concentrations facilitated better CO2 penetration into the hydrate structure, leading to increased methane recovery and improved CO2 storage.
JOURNAL OF NATURAL GAS SCIENCE AND ENGINEERING
(2022)
Article
Engineering, Mechanical
Bo-Wen Sun, Sheng-Qi Yang, Jie Xu, Peng-Fei Yin
Summary: Based on the discrete element method, this study established a numerical model to investigate the macro- and meso-mechanical properties of bedded shale under different unloading paths and bedding inclinations. The results revealed that bedding inclination has a significant influence on mechanical parameters and failure modes under unloading. The peak strength and ultimate bearing capacity showed a U-shaped trend, with maximum values observed at beta = 0 degrees or beta = 90 degrees and minimum values at beta = 30 degrees or beta = 45 degrees. The failure modes varied depending on the bedding inclination, with splitting damage observed at lower initial confining pressure for beta = 0 degrees and shear-slip damage observed for beta = 15-45 degrees. Shale specimens with beta = 60-90 degrees exhibited conjugate shear damage intersecting with the weak surface. The damage caused by unloading and increasing axial stress was greater than that caused by unloading and constant axial strain. The effects of beta = 0 degrees and 90 degrees on microcracking and stress distribution within the specimen were significantly smaller compared to other bedding inclinations.
THEORETICAL AND APPLIED FRACTURE MECHANICS
(2022)
Article
Computer Science, Interdisciplinary Applications
Sheng-Qi Yang, Ye Li, Guo-Wei Ma, Bo-Wen Sun, Jing Yang, Jie Xu, Yong-Hao Dai
Summary: The dynamic compression experiments were conducted on granite specimens after high-temperature treatments, and the fragmentation characteristics were evaluated using fractal dimension and average fragment size. The results showed that the physical properties of the granite were closely related to the temperature, and microcracking occurred at 900 degrees Celsius. The fractal dimension and average fragmentation size were found to be inversely linearly related, and the crack propagation during dynamic compression followed a pattern of initial appearance on the surface and gradual propagation to the interior.
COMPUTERS AND GEOTECHNICS
(2023)
Article
Engineering, Geological
Zhen Yang, Sheng-Qi Yang, Wenbo Zheng, Dwayne D. Tannant
Summary: This paper presents an improved multi-layer computational method based on fully coupled thermal-mechanical OSB-PD for simulating fracturing in granite under coupled thermal-hydraulic effects. The method includes four computational layers and was verified through simulation and comparison with experimental results. It successfully predicts the behavior of granite specimens subjected to HTHP hydraulic fracturing tests.
INTERNATIONAL JOURNAL OF ROCK MECHANICS AND MINING SCIENCES
(2022)
Article
Green & Sustainable Science & Technology
Jinzhou Tang, Shengqi Yang, Ke Yang, Wenling Tian, Guangjian Liu, Minke Duan
Summary: A new thermal damage numerical model was proposed to analyze the cracks on pre-cracked red sandstone after thermal treatment. The thermal damage value, obtained by extracting the thermal crack area from SEM images, served as an indicator of the degree of thermal damage. By replacing the flat-joint model with the smooth-joint model based on the thermal damage value, the mechanical behavior and failure patterns of sandstone were accurately simulated. In addition, the critical temperature for strength reduction was found to be 750 degrees C.
Article
Energy & Fuels
Sheng-Qi Yang, Shuai-Bo Xu, Zhen Liu, Bo-Wen Sun, Peng-Fei Yin
Summary: In this study, stress-strain curves of sandstone soaked in 5% NaCl and 5% K2SO4 solutions were obtained under different loading and unloading paths. The results showed that sandstone soaked in 5% NaCl exhibited greater unloading capacity compared to sandstone soaked in 5% K2SO4. The strain change rate during the unloading process was higher for sandstone soaked in 5% K2SO4. The deformation modulus and Poisson's ratio of sandstone soaked in 5% NaCl were greater and less than those of sandstone soaked in 5% K2SO4, respectively. The total energy absorbed by sandstone soaked in 5% NaCl was always lower than that soaked in 5% K2SO4.
GEOMECHANICS AND GEOPHYSICS FOR GEO-ENERGY AND GEO-RESOURCES
(2023)
Article
Energy & Fuels
Pengfei Yin, Shengqi Yang, Feng Gao, Wenling Tian
Summary: Drilling wellbores in shale reservoirs can lead to instability due to the stress release and change in stress equilibrium. This study investigated the strength, failure, strain energy evolution, and micro-crack damage of shale specimens under confining pressure unloading conditions. The research revealed that confining pressure unloading induces greater plastic deformation, more micro-crack damage, and a more complex failure pattern.
Editorial Material
Energy & Fuels
Chun Zhu, Shengqi Yang, Yuanyuan Pu, Lijun Sun, Min Wang, Kun Du
Article
Engineering, Geological
Yu Song, Sheng-Qi Yang, Ke-Sheng Li, Peng-Fei Yin, Peng-Zhi Pan
Summary: This study establishes a three-dimensional numerical model to investigate the failure behavior of transversely isotropic rock formations, with a focus on the effects of confining pressure and laminar inclination angle. The results of the numerical simulations show that the confining pressure and laminar angle significantly influence the internal crack evolution patterns of the specimen.
ROCK MECHANICS AND ROCK ENGINEERING
(2023)
Article
Engineering, Geological
V. R. S. De Silva, H. Konietzky, H. Mearten, P. G. Ranjith, W. G. P. Kumari
Summary: This study proposes a novel approach called the hybrid rock pre-conditioning method to enhance the sustainability and efficiency of low-grade ore mining. The method involves the use of soundless cracking demolition agents (SCDAs) to initiate radial fractures in a predrilled host rock, followed by hydraulic stimulation to extend the fractures. The results show that this method can create a high density of fractures around the injection well, and key factors such as rock mass heterogeneity and stress anisotropy affect its performance.
ROCK MECHANICS AND ROCK ENGINEERING
(2023)
Article
Energy & Fuels
M. H. Samarakoon, P. G. Ranjith
Summary: Ensuring the intactness of cement sheaths is crucial for deep well applications in extreme underground conditions. This study investigates the behavior of wellbore materials, including steel casing, annulus cement sheaths, and surrounding rock formations, under continuous steam injection. The results show that materials in carbonate formations are more vulnerable to stress than those in sandstone formations, and the retention time of maximum temperature in cement sheaths is shorter in sandstone than in carbonate. It is also found that the cement sheaths in compliant formations like sandstone may fail due to tensile cracking along the thinnest thickness.
GEOENERGY SCIENCE AND ENGINEERING
(2023)
