Article
Engineering, Mechanical
Fan Xiao, De-Yi Jiang, Fei Wu, Jie Chen, Jian-Zhi Zhang, Wei Liu
Summary: The research finds that the ultimate bearing capacity of sandstone samples increases as the level of maximum principal stress at the unloading point increases, but the samples are more prone to collapse during unloading, with a shift in failure mode from mixed tensile-shear failure to shear failure. Additionally, as the level of maximum principal stress increases, the number of accumulative micro-cracks and the rate of micro-crack generation also increase, while the ratio between tensile micro-cracks and shear micro-cracks generally decreases.
FATIGUE & FRACTURE OF ENGINEERING MATERIALS & STRUCTURES
(2021)
Article
Engineering, Chemical
Ziyi Wang, Hengyu Su, Chang Luo, Shu Ma, Heng Ding
Summary: This study investigated the mechanical response characteristics and fracture mechanism of fractured sandstone under true triaxial stress using matdem particle flow software. The results showed that increasing the intermediate principal stress is beneficial for enhancing the strength and fracture degree of sandstone, ultimately forming interlacing macroscopic cracks.
Article
Engineering, Geological
Yaohui Gao, Kezhong Wang, Chang Zhou
Summary: By using 3D discrete element method (DEM) to conduct simulated true triaxial compression tests on jointed marble, this study investigated the influence of intermediate principal stress and joint inclined angle on the macroscopic mechanical characteristics of rock mass. The study found a strong dependency of strength and failure mechanism on the intermediate principal stress, and significant influence of joint inclined angle on the strength and failure characteristics.
Article
Chemistry, Multidisciplinary
Lan Cui, Wenzhao Cao, Qian Sheng, Mingxing Xie, Tao Yang, Ping Xiao
Summary: By experiment and simulation, the performance of layered geogrid-sand-clay reinforced structures was studied, showing that laying sand layers and embedding geogrids in sand layers can improve the mechanical properties of the structure and increase the shear strength index.
APPLIED SCIENCES-BASEL
(2021)
Article
Engineering, Chemical
Pengtao Zhang, Xinjian Sun, Xinjie Zhou, Yuxiang Zhang
Summary: This paper presented a reliable calibration method considering a flexible boundary to calibrate the microscopic parameters in the DEM. By analyzing the sensitivity of microscopic parameters to macroscopic responses and using the response surface method to capture the nonlinear relationship between them, the study showed that DEM can accurately simulate the rockfill compression process with a reliable parameter calibration method.
Article
Engineering, Chemical
Peng Bu, Yanlong Li, Xin Zhang, Lifeng Wen, Wen Qiu
Summary: This study proposes a method to address the issues of large amount of calculation and low efficiency in the calibration of discrete element method (DEM) contact model parameters for rockfill, which is based on the experimental design method. Plackett-Burman design method was used to analyze the significance of each contact model parameter to the macro-mechanical parameters. Second-order response surface regression models were developed to analyze the relationship between macro-mechanical parameters and contact model parameters that have significant impact on them. The calibrated parameters were then used to simulate discrete element triaxial tests of the rockfill under varying pressure conditions, and the study demonstrates their accuracy in predicting the macroscopic behavior of rockfill.
Article
Green & Sustainable Science & Technology
Yingwei Wang, Weihang Du, Dongming Zhang, Beichen Yu
Summary: This study aims to determine the safe tunnelling rate of the roadway by examining the instability and failure characteristics of surrounding rock under different disturbance stresses in deep underground roadway excavation. Results showed that the mechanical properties, deformation, and failure characteristics of sandstone differed under different loading and unloading rates. Additionally, the expansion of the rock went through three critical stages, with the final stage being the longest.
Article
Energy & Fuels
Junwen Zhang, Wenbing Fan, Weimin Niu, Shanyong Wang
Summary: Stress path and occurrence depth have significant effects on the energy evolution properties of deep rock. Triaxial tests were conducted to investigate the energy evolution characteristics and distribution process of deep sandstone under different simulated depths and stress paths. The results show that the energy of deep sandstone is positively correlated with the simulated depth under similar stress paths. The energy under one-sided unloading conditions of X-direction stress is greater than that under two-sided unloading conditions, which is greater than that under one-sided unloading conditions of X- and Y-direction stresses. The ratio k of deep sandstone exhibits different trends with increasing Z-direction strain at different simulated depths. Simulated depth is positively correlated with the initial energy storage and energy storage limit of deep sandstone under the same stress path. The pre-peak energy dissipation rate of deep sandstone decreases gradually with increasing simulated depth, while the post-peak energy dissipation rate increases gradually.
GEOMECHANICS AND GEOPHYSICS FOR GEO-ENERGY AND GEO-RESOURCES
(2022)
Article
Engineering, Chemical
Lei Gao, Bingbing Wei, Xiaochuan Hu, Zaifeng Yao, Yiwen Fang, Xuejian Gao
Summary: In this study, a numerical model of sand triaxial test was established using discrete element software PFC3D, and an indoor triaxial test was conducted to calibrate the numerical model. The influence of microscopic parameters on the macroscopic mechanical response of sand was analyzed. The results showed that the friction coefficient had the greatest impact on the peak strength and residual strength of the sand's stress-strain curve, and it was positively correlated. The normal tangential stiffness ratio was negatively correlated, while the porosity and boundary flexibility stiffness had minimal influence on it.
Article
Engineering, Geological
Cyrille Couture, Pierre Besuelle
Summary: This study investigates the effect of deviatoric loading paths on diffuse and localized deformation in a high porosity Vosges sandstone during mechanical loading. The results show a transition from diffuse to localized deformation with an intermediate step of early strain localization, and the evolution of localization patterns is dependent on both an increase in mean stress and a decrease in Lode angle.
INTERNATIONAL JOURNAL OF ROCK MECHANICS AND MINING SCIENCES
(2022)
Article
Engineering, Chemical
Junqi Zhang, Xiaobin Chen, Jiasheng Zhang, Peerapong Jitsangiam, Xiang Wang
Summary: The study investigates the mechanical properties of rigid-grain and soft-chip mixtures through numerical simulations. Increasing the volumetric chip content leads to higher toughness, deviatoric peak stress, and shear strain, as well as significant changes in friction angles. Strong contact force chains and anisotropy were observed in micro-mechanical features, with implications for granular mixture mechanics and geomechanics.
Article
Engineering, Geological
Jun Zhao, Liang Hu, Xiating Feng, Yaxun Xiao, Yue Guo
Summary: The shear mechanical properties are important factors in rock mass failure. However, there is a lack of research on the shear mechanical behavior of rocks under three-dimensional stress, especially considering the influence of lateral stress on shear failure mechanism. This study conducted direct shear, true triaxial stress shear, and confining shear tests to investigate the deformation, failure modes, strength, and surface roughness of sandstone. The study also focused on studying the influence of lateral stress on the shear failure mechanism of sandstone under true triaxial stress by analyzing the acoustic emission characteristics during failure.
ROCK MECHANICS AND ROCK ENGINEERING
(2023)
Article
Computer Science, Interdisciplinary Applications
Jianguo Li, Bin Wang, Di Wang, Pei Zhang, Philip. J. Vardon
Summary: In this paper, a coupled MPM-DEM formulation is proposed to accurately and efficiently model the mechanical behavior of soil-rock mixtures. The method combines the material point method (MPM) to model soil continua and the discrete element method (DEM) to model rocks, with their contact forces linked concurrently. The validity and capability of this method are demonstrated through various tests and comparisons with pure DEM simulations and laboratory tests. Additionally, a coarse-graining modeling scheme is implemented to significantly increase computational efficiency. The proposed method provides a novel approach for simulating large-scale soil-rock mixtures in nature or engineering.
COMPUTERS AND GEOTECHNICS
(2023)
Article
Engineering, Geological
Mathias Tolomeo, Glenn R. McDowell
Summary: This paper assesses two different methods for modeling real particle shapes in 3D discrete element method (DEM) simulations and applies them to triaxial tests on railway ballast. The results show that using clumps can achieve higher shear strength closer to the experimental response. A micromechanical analysis reveals the influence of particle shape on the mechanics, particularly the concave shape. Additionally, the combined effect of particle shape and interparticle friction coefficient on shear strength is evaluated.
INTERNATIONAL JOURNAL OF ROCK MECHANICS AND MINING SCIENCES
(2022)
Article
Computer Science, Interdisciplinary Applications
Xuejian Li, Kang Duan, Qiangyong Zhang, Jiarun Li, Rihua Jiang, Luchao Wang
Summary: The permeability of hydrocarbon reservoirs composed of porous rock is anisotropic under asymmetrical stress configuration. The permeability sensitivity of porous sandstone to stresses is investigated by experiments and simulations. An analytical model is proposed to calculate the components of tensorial permeability affected by stresses and evaluate the evolution of permeability anisotropy. The prediction of permeability sensitivity behaviors and anisotropy to stresses are consistent with experimental and simulated results.
COMPUTERS AND GEOTECHNICS
(2023)
Article
Energy & Fuels
Kang Duan, Yingchun Li, Wendong Yang
Summary: The study investigates the impact of well distance, spacing between injection points, and arrangement of injection points on hydraulic fracturing efficiency. It was found that the distance between wells only enhances efficiency when the spacing reaches 40 m, and increasing the spacing between injection points effectively mitigates stress shadowing effect and promotes fracturing efficiency when the distance exceeds 60 m. Arrangement of injection points has a negligible role compared to the spacing among them.
GEOMECHANICS AND GEOPHYSICS FOR GEO-ENERGY AND GEO-RESOURCES
(2021)
Review
Engineering, Environmental
Zhenjie Zhang, Qiangyong Zhang, Kang Duan, MingYang Ren, Xiangjie Yin, Hanxiang Lin, Wen Xiang
Summary: The study found that osmotic pressure can reduce rock strength, while confining pressure has the opposite effect; as osmotic pressure increases, rock permeability also increases; cracks gradually become tortuous and rough as osmotic pressure increases.
BULLETIN OF ENGINEERING GEOLOGY AND THE ENVIRONMENT
(2021)
Article
Engineering, Geological
Luchao Wang, Kang Duan, Qiangyong Zhang, Xuejian Li, Rihua Jiang
Summary: In this study, the dynamic propagation of fractures in granite samples under various injection schemes and initial stress conditions using SCDA was experimentally investigated. The experimental results showed that SCDA had a strong fracturing capacity, and the stress shadowing effect between the boreholes led to a more complicated fracture propagation mode in the early stage.
ROCK MECHANICS AND ROCK ENGINEERING
(2022)
Article
Engineering, Geological
Rihua Jiang, Kang Duan, Qiangyong Zhang
Summary: This study systematically investigates the discrepancies between the Brazilian test and direct tensile test by using three-dimensional Flat-joint model simulation, and finds that microstructural heterogeneity significantly affects the tensile strength of rocks.
ROCK MECHANICS AND ROCK ENGINEERING
(2022)
Article
Engineering, Geological
Kai Broeker, Xiaodong Ma
Summary: The hydraulic fracturing technique is commonly used to estimate in situ stress field. A measurement campaign was conducted in Bedretto Underground Laboratory in the Swiss Alps, using vertical boreholes and different methods to determine the fracture closure pressure. The most consistent results were obtained using the inflection point and bilinear pressure decay rate method. The stress environment around BedrettoLab was found to be transitional between normal and strike-slip faulting, and the in situ stress field may have been significantly perturbed by drainage, cooling, and excavation damage zone of the tunnel.
ROCK MECHANICS AND ROCK ENGINEERING
(2022)
Article
Physics, Fluids & Plasmas
G. C. Yang, L. Jing, C. Y. Kwok, Y. D. Sobral
Summary: The study found that larger underwater granular collapses result in higher flow mobility and longer runout distances. This is due to the larger column size transferring more potential energy into kinetic energies of the fluid and particles, leading to a more efficient energy conversion and higher mobility in larger cases.
PHYSICAL REVIEW FLUIDS
(2021)
Article
Geosciences, Multidisciplinary
Yinlin Ji, Hannes Hofmann, Kang Duan, Arno Zang
Summary: Induced seismicity from fluid injection into underground formations poses a threat to sustainable utilization of the subsurface. Laboratory experiments have played a crucial role in understanding the fault behavior related to injection-induced seismicity. This review provides an overview of the current understanding of injection-induced seismicity from the laboratory perspective. It covers the basics of fault behavior, laboratory methods, and the effects of various factors on fault behavior, with a focus on implications for injection-induced seismicity. The review highlights the advancements made in understanding the role of fault properties, stress state, fluid physics, and injection protocol in injection-induced seismicity. However, there are still unresolved questions that could be addressed in future experimental studies.
EARTH-SCIENCE REVIEWS
(2022)
Article
Engineering, Geological
Hanxiang Lin, Qiangyong Zhang, Longyun Zhang, Kang Duan, Tianen Xue, Qinghan Fan
Summary: An accurate understanding of how water affects time-dependent deformation in rocks is crucial for assessing the long-term stability of geotechnical projects. Triaxial compression rheological tests were conducted to investigate the effects of water content and stress level on creep strain, creep rate, long-term strength, and creep failure mode. The experiments revealed that increases in water content and stress level gradually activate the time-dependent characteristics of rocks. Water content and stress level significantly increase instantaneous strain, creep strain, and steady creep strain rate, but decrease the time to dilatancy and the time to failure.
ROCK MECHANICS AND ROCK ENGINEERING
(2022)
Article
Computer Science, Interdisciplinary Applications
Zhenjie Zhang, Qiangyong Zhang, Kang Duan, Ruixin Zhang, Hanxiang Lin, Wen Xiang
Summary: When the buried depth of underground engineering is greater than 1000 meters, the deep surrounding rock exhibits typical nonlinear deformation characteristics due to the coupling effect of high in-situ stress and high seepage pressure. By establishing a fully coupled hydraulic-mechanical analytical model and verifying the reliability of the calculation program, an anti-seepage optimization design for deep tunnels was conducted.
COMPUTERS AND GEOTECHNICS
(2022)
Article
Green & Sustainable Science & Technology
Gaosheng Wang, Xiaodong Ma, Xianzhi Song, Gensheng Li
Summary: The enhanced geothermal system plays a key role in developing deep geothermal resources, and understanding the flow and heat transfer in fractures is crucial for its efficient operation.
JOURNAL OF CLEANER PRODUCTION
(2022)
Article
Engineering, Geological
Jiarun Li, Kang Duan, Han Meng, Jianbo Wang, Qiangyong Zhang, Luchao Wang
Summary: The microstructure of conglomerate plays a significant role in its mechanical properties. The deformation and failure modes of conglomerate vary under different confining pressures. The size of the gravel has a noticeable influence on the mechanical characteristics of conglomerate. Microscopic observations provide insights into the deformation process, and a conceptual model is proposed to describe the deformation of conglomerate.
ROCK MECHANICS AND ROCK ENGINEERING
(2023)
Article
Engineering, Geological
Tianen Xue, Qiangyong Zhang, Kang Duan, Pengfei Wang, Hanxiang Lin, Qinghan Fan, Lei Liu
Summary: This study investigates the mechanism of water inrush induced by zonal disintegration under hydro-mechanical coupling through a true three-dimensional geo-mechanical model test. The results reveal that zonal disintegration may induce water inrush during tunnel excavation under the coupling action of high stress and high seepage pressure. The oscillating stress in the rock mass caused by excavation disturbance leads to the alternating appearance of rupture and non-rupture zones around the tunnel. With the increase of seepage pressure, the non-rupture zone, acting as the water barrier, is damaged and connects with the rupture zone to form a water inrush channel.
INTERNATIONAL JOURNAL OF ROCK MECHANICS AND MINING SCIENCES
(2022)
Article
Construction & Building Technology
Fan Li, Qiangyong Zhang, Kang Duan, Wen Xiang, Guangyuan Yu
Summary: Due to excavation-induced unloading, high sidewalls of underground powerhouse often experience splitting failure, which has negative effects on cavern construction. To understand the formation mechanism of splitting failure, a novel elastic-plastic damage softening model was proposed based on strain gradient theory and elastic-plastic damage theory. Numerical solution of displacement and stress of circular cavern using the proposed model is obtained by using the ODE45 program and the complex function method. The analysis results are consistent with geomechanical model test results, indicating that the stress variation with alternating peaks and troughs is the mechanical mechanism of splitting failure in high sidewalls of the underground powerhouse.
TUNNELLING AND UNDERGROUND SPACE TECHNOLOGY
(2023)
Article
Geochemistry & Geophysics
Shihuai Zhang, Xiaodong Ma, Kai Broker, Rutger van Limborgh, Quinn Wenning, Marian Hertrich, Domenico Giardini
Summary: Characterizing the in situ stress state within fault zones is challenging but essential for understanding earthquake processes, fluid flow, and subsurface engineering. In this study, an array of inclined boreholes in the Bedretto Underground Laboratory in the Swiss Alps was used to observe the breakouts and identify natural geologic structures intersecting the fault zone. By analyzing the breakout rotations and utilizing the stress field around the boreholes, the stress variations within and outside the fault zone were estimated. The results provide insights into the spatial relationship between stress state and fault structure.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2023)
Article
Engineering, Multidisciplinary
Kang Duan, Ri-hua Jiang, Xue-jian Li, Lu-chao Wang, Ze-ying Yang
Summary: Damage in rock mass is influenced by joints and stress induced by human activities. A proper representation of the loading path is crucial for understanding mechanical behaviors. Using the DEM, the impact of loading path on rock specimen cracking is examined. The model's effectiveness is confirmed by comparing results to existing research.
JOURNAL OF ZHEJIANG UNIVERSITY-SCIENCE A
(2023)