Article
Mining & Mineral Processing
Wei You, Feng Dai, Yi Liu, Hongbo Du, Ruochen Jiang
Summary: This study introduces a numerical servo triaxial Hopkinson bar (NSTHB) to investigate the dynamic responses of rocks under a true triaxial stress state. The results indicate that the increase in intermediate principal stress leads to an increase in dynamic strength and elastic modulus of rocks, while the dynamic elastic modulus remains independent of the dynamic strain rate. Additionally, the study shows that the intermediate principal stress significantly affects the dynamic failure modes of rocks.
INTERNATIONAL JOURNAL OF MINING SCIENCE AND TECHNOLOGY
(2021)
Article
Mechanics
Fan Feng, Shaojie Chen, Zhenyu Han, Naser Golsanami, Peng Liang, Zhiwei Xie
Summary: The presence of water has a significant influence on the failure properties of underground surrounding rock. This study investigated the crack propagation behavior of red sandstone under different moisture contents and intermediate principal stresses. The results showed that the failure mode can be categorized into shear, tension with shear, and slabbing. The increase in moisture content and intermediate principal stress led to an increase in extensional cracks and a decrease in shear cracks. The analysis also indicated that the presence of water can restrain rockburst, and the intermediate principal stress plays a distinct role in the failure behavior of natural and saturated sandstone.
ENGINEERING FRACTURE MECHANICS
(2023)
Article
Engineering, Mechanical
Y. Zhang, J. Zhang, W. Du, H. Wang, K. Niu
Summary: A true triaxial seepage experimental apparatus was developed to conduct a series of coal seam gas seepage experiments. The results showed that the gas permeability of coal seams varies under different stress states, with an increase in permeability as gas pressure decreases, and the turning point between the Klinkenberg effect and gas wedging effect was determined. The concept of average effective stress was proposed, identifying its dominant influence on coal seam permeability.
EXPERIMENTAL TECHNIQUES
(2021)
Article
Engineering, Geological
Chongyang Wang, Dongming Zhang, Beichen Yu, Shujian Li
Summary: The true triaxial loading-unloading tests of coal samples were conducted to analyze the deformation, seepage, damage, strength, and failure characteristics. The impact of gas pressure on permeability and yield conditions were investigated, and numerical simulation software was used to verify the true triaxial loading-unloading process. The results showed that the volumetric strain of the samples underwent a process of compaction, flatness, and re-compaction with time. The permeability was negatively correlated with volumetric strain. The damage factor and initial damage point of the samples increased with gas pressure, and the sample experienced different behaviors at different pressures.
ROCK MECHANICS AND ROCK ENGINEERING
(2023)
Article
Engineering, Geological
Jian-Feng Liu, Xing Luo, Gan Feng, Lu-Lin Zhou, Xing-Guo Yang, Gong-Da Lu
Summary: The study examines the influence of thermal exposure on rock response over the long term, focusing on the enhanced geothermal system and geological disposal of radioactive waste. Triaxial creep experiments on thermally-stressed Beishan granite reveal that thermal cracking and hydro-static compaction reshape the crystalline fabric and significantly affect creep deformation. This research provides insights into time-dependent rock deformation and its implications for decarbonized electricity production and sustainable energy transition.
INTERNATIONAL JOURNAL OF ROCK MECHANICS AND MINING SCIENCES
(2023)
Article
Engineering, Geological
Manuel A. Gonzalez-Fernandez, Xian Estevez-Ventosa, Leandro R. Alejano, Hossein Masoumi
Summary: Understanding size effects is crucial for analyzing the behavior of rocks and rock masses in different scales and applications. This study conducted triaxial tests on granite samples with different confinements and sizes. The results showed that size effects were less dominant at high confining pressures for peak and residual strengths. The study also analyzed size-dependent rock strength theories and found good agreement between models and laboratory data.
ROCK MECHANICS AND ROCK ENGINEERING
(2023)
Article
Engineering, Geological
Lihua Hu, Liyuan Yu, Minghe Ju, Xiaozhao Li, Chun'an Tang
Summary: The effect of intermediate stress on strainbursts is studied using a 3D bonded block distinct element method (DEM). The DEM model accurately captures the stress-strain response, failure pattern, and energy balance of strainbursts compared to experimental results. Increasing intermediate stress enhances the peak strain, yield stress, and rock strength of strainbursts, while also increasing tensile and shear cracks and the intensity of strainbursts. The Mogi criterion is applied to construct new strength criteria for strainbursts.
JOURNAL OF ROCK MECHANICS AND GEOTECHNICAL ENGINEERING
(2023)
Article
Metallurgy & Metallurgical Engineering
Xiao Ma, Gui-ling Wang, Da-wei Hu, Hui Zhou
Summary: In this study, hydraulic fracturing experiments were conducted on granite at room temperature and 200 degrees C under different true triaxial stress to analyze their different fracturing mechanisms. The results showed that hydraulic fracturing at 200 degrees C can significantly reduce the breakdown pressure and fracture initiation pressure compared to hydraulic fracturing at room temperature. Moreover, the increase in fracturing volume at 200 degrees C was caused by the increment of micro-scale crack in the fractured sample, as observed from the nuclear magnetic resonance result.
JOURNAL OF CENTRAL SOUTH UNIVERSITY
(2023)
Article
Engineering, Geological
Ben-Guo He, Xiang-Rui Meng, Xia-Ting Feng, Sa Li, Yonghong Li
Summary: The failure modes of deep excavation are related to three-dimensional stresses. The effect of the intermediate principal stress (a2) on the failure of granite surrounding an underground powerhouse was examined. The stress a2 after excavation can help improve the failure brittleness and strength of the rock.
ENGINEERING GEOLOGY
(2022)
Article
Mining & Mineral Processing
Zhongwei Wang, Quansheng Liu
Summary: The study proposed a strength criterion for soft rocks, which includes two independent parameters: uniaxial compressive strength and f(joint) for characterizing rock mass quality. Comparisons showed that the new criterion generally produced a better fit for estimating triaxial and true-triaxial strengths, even without triaxial data.
INTERNATIONAL JOURNAL OF MINING SCIENCE AND TECHNOLOGY
(2021)
Article
Engineering, Geological
Qiao-Juan Yu, Qi-Zhi Zhu, Liang Chen, Jian-Fu Shao
Summary: This article investigates the mechanical behaviors of Beishan granite, the host rock for China's high-level radioactive waste disposal program, through experimental and numerical methods. The results demonstrate the rock's typical brittle behavior, with peak strength influenced by confining pressure, and its creep behavior extensively dependent on deviatoric stress. A micromechanical friction-damage coupling model is proposed for constitutive modeling, showing its suitability for Beishan granite. The results obtained from tests are analytically simulated, and creep damage is treated within the damage-friction coupling framework. Semi-analytical simulations of creep tests exhibit satisfactory agreement.
ROCK MECHANICS AND ROCK ENGINEERING
(2022)
Article
Materials Science, Multidisciplinary
Zhi Zheng, Hongyu Xu, Benguo He, Chengxiang Yang, Shuling Huang, Xiaohua Huang, Jiaju Zhou, Wei Wang
Summary: This research conducted true triaxial compression tests to study the influence of sigma(2) and sigma(3) on the mechanical properties of marble in deep underground engineering excavation. It found that sigma(2) and sigma(3) affect the peak strength, crack initiation stress, and damage stress of the rock, while the variation of residual strength is different from that of peak strength. Furthermore, increasing sigma(2) or decreasing sigma(3) reduces the pre-peak plasticity of the rock and significantly changes the shape of the post-peak curve.
INTERNATIONAL JOURNAL OF DAMAGE MECHANICS
(2023)
Article
Engineering, Geological
Jian Zhou, Rui Zhang, Yingui Qiu, Manoj Khandelwal
Summary: Rock strength is crucial for underground projects, and this study utilizes a GEP algorithm-based model to predict true triaxial strength, considering the influence of rock genesis. The proposed criterion shows superior prediction accuracy and stability compared to existing models.
JOURNAL OF ROCK MECHANICS AND GEOTECHNICAL ENGINEERING
(2023)
Article
Engineering, Geological
Jian Zhou, Rui Zhang, Yingui Qiu, Manoj Khandelwal
Summary: This study uses a gene expression programming (GEP) algorithm-based model to predict the true triaxial strength of rocks and obtains a strength criterion for different types of rocks. The strength criterion based on the GEP model exhibits superior prediction accuracy and stability compared to existing criteria.
JOURNAL OF ROCK MECHANICS AND GEOTECHNICAL ENGINEERING
(2023)
Article
Engineering, Geological
Xu Chang, Xu Zhang, Faning Dang, Bafang Zhang, Fangqiang Chang
Summary: An experimental study was conducted to investigate the failure behavior of sandstone specimens containing a single flaw under true triaxial compression. The influences of the intermediate principal stress on cracking pattern, stress-strain response, and acoustic emission activities were analyzed. The results showed that the specimen strength increased with a higher intermediate principal stress. The crack initiation stress initially increased and then decreased with an increase in the intermediate principal stress. The flawed specimens typically failed due to anti-wing cracks, regardless of the flaw inclination angle and the intermediate principal stress. The proportion of shear cracks was higher than that of tensile cracks during the cracking process.
ROCK MECHANICS AND ROCK ENGINEERING
(2022)
Article
Engineering, Civil
Susheng Wang, Huanling Wang, Weiya Xu, Ming Cai
Summary: A series of tests were conducted to investigate the mechanical behavior of rock under different loading conditions. The results show that lateral deformation is more sensitive than axial deformation under unloading process. Based on experimental data, a coupled elasto-plastic damage model was proposed, which successfully described the main mechanical behaviors of the rock under complex loading conditions.
EUROPEAN JOURNAL OF ENVIRONMENTAL AND CIVIL ENGINEERING
(2022)
Article
Engineering, Civil
Huanling Wang, Kai Zhao, Xiao Qu, Jianrong Xu, Ming Cai
Summary: This study investigates the hydro-mechanical properties of rock-like materials with intermittent joints under different confining and hydraulic pressures. The results show that the strength, permeability, and deformation properties of the specimens were influenced by hydraulic pressure, and the evolution of permeability is closely correlated with the development of joints and cracks within the specimen.
EUROPEAN JOURNAL OF ENVIRONMENTAL AND CIVIL ENGINEERING
(2023)
Article
Engineering, Geological
Shuai Xu, Pengyuan Hou, Runran Li, Ming Cai
Summary: The application of conventional SCDAs is complicated due to extrusion and difficulty in wet or up-tilt boreholes. An innovative self-swelling cartridge (SSC) is developed to address these issues, which shows promising expansibility and mechanical properties. The SSC has a recommended agent packing density of 1.65 g/cm(3) and is easy to use, making it suitable for fracturing rock masses in various borehole conditions.
ROCK MECHANICS AND ROCK ENGINEERING
(2021)
Article
Engineering, Geological
Mingzheng Wang, Ming Cai
Summary: This study focuses on the time-dependent strength and deformation of unweathered clean rock joints through establishing joint models and conducting creep simulations to investigate factors influencing their long-term shear strength and sliding velocity. The results reveal that normal stress has more influence than joint roughness on resisting creep slipping of the joints. A creep slipping model for simplified flat joints is proposed to model the long-term shear strength and sliding velocity of joints under creep deformation conditions.
ROCK MECHANICS AND ROCK ENGINEERING
(2021)
Article
Engineering, Geological
Alex Hall, Brad Simser, Ming Cai
Summary: This study identified four factors influencing the deterioration of a 3 m diameter bored raise in a hard rock mine in Sudbury, Canada, and found that these factors often work simultaneously, leading to overbreak beyond the original bored dimension. The findings are important for improving understanding of brittle rock failure and making better engineering decisions for ground support and blasting.
INTERNATIONAL JOURNAL OF ROCK MECHANICS AND MINING SCIENCES
(2021)
Article
Engineering, Geological
Mingzheng Wang, Ming Cai
Summary: The time-dependent deformation of brittle rock pillars was investigated using laboratory-scale pillar models and the grain-based time-to-failure model (GBM-TtoF). It was found that the GBM-TtoF creep model can properly simulate the time-dependent strength and deformation of rock pillars. Factors such as pillar shape and loading ratio influence the time-dependent behavior of the pillars.
INTERNATIONAL JOURNAL OF ROCK MECHANICS AND MINING SCIENCES
(2021)
Article
Engineering, Geological
Danqi Li, Ming Cai, Hossein Masoumi
Summary: This study introduces a novel constitutive model to characterize the mechanical behavior of cable bolts under axial loading and different boundary conditions, and validates the model's credibility by simulating the full load-displacement performance of cable bolts. The cone shaped failure mode of grout is found to significantly affect the load carrying capacity of cable bolts under axial loading.
INTERNATIONAL JOURNAL OF ROCK MECHANICS AND MINING SCIENCES
(2021)
Article
Engineering, Geological
Hossein Rafiei Renani, Ming Cai
Summary: The Hoek-Brown failure criterion is widely used for estimating rock mass strength by integrating intact rock properties and geological characteristics. Strength degradation relations play a key role in downgrading intact rock strength to estimate rock mass strength. Despite the relative simplicity of determining intact rock properties from laboratory tests, quantifying geological characteristics remains challenging. Understanding the basis and development of the Hoek-Brown failure criterion is crucial for its proper use.
ROCK MECHANICS AND ROCK ENGINEERING
(2022)
Article
Engineering, Geological
Mingzheng Wang, Ming Cai
Summary: A new creep model was developed to simulate time-dependent responses of jointed rock mass, and its implementation in UDEC demonstrated the influence of joint properties on the long-term stability of rock masses. A case study of a high rock slope in western Norway analyzed the creep deformation mechanisms of the rock mass and found no unstable movement on potential sliding surfaces. The proposed creep model provides a novel approach to analyze structural failures of jointed rock mass under creep loading conditions.
ROCK MECHANICS AND ROCK ENGINEERING
(2022)
Article
Engineering, Geological
P. Y. Hou, M. Cai, X. W. Zhang, X. T. Feng
Summary: The study systematically analyzed the effects of axial- and lateral-strain-controlled loadings on the strength and post-peak deformation behaviors of brittle rocks. Different rock types showed varying responses under these loading conditions, with higher peak strength and lower residual strength observed under axial-strain-controlled loading. The unloading of the actuator in response to the servo-control system to maintain a constant lateral strain rate was identified as a key factor causing Class II post-peak stress-strain curves during lateral-strain-controlled loading.
ROCK MECHANICS AND ROCK ENGINEERING
(2022)
Article
Engineering, Geological
P. Y. Hou, M. Cai
Summary: This study systematically explores the influence of Loading Environment System Stiffness (LESS) on post-peak stress-strain curves and failure modes of brittle hard rocks. The results show that lower LESS leads to steeper post-peak descending slopes of stress-strain curves, while higher LESS results in gentler slopes. Additionally, as LESS increases, AE events transition from a concentrated distribution near peak strength to a dispersed distribution throughout the post-peak deformation stage. The number of splitting macrocracks and the degree of damage decrease with increasing LESS, indicating a more stable post-peak failure process. The study also analyzes the mechanism behind the different post-peak descending slopes under different LESS through the variations of axial stress, axial and lateral strains, rates of axial and lateral strains over time. Fitting formulas relating LESS to the post-peak deformation modulus are established, and the importance of considering LESS for accurate parameters in rock engineering design and analysis is discussed.
ROCK MECHANICS AND ROCK ENGINEERING
(2022)
Article
Engineering, Geological
Mingzheng Wang, Ming Cai
Summary: By investigating the time-dependent deformation behaviors of tunnels excavated in jointed rock masses, this study validates the effectiveness of a creep model implemented in distinct-element method code. The simulation results align with field data, and the weakening of rock mass simulated using the internal pressure reduction method is validated as well.
ROCK MECHANICS AND ROCK ENGINEERING
(2022)
Article
Engineering, Geological
P. Y. Hou, M. Cai
Summary: Understanding the strength and deformation behaviors of rock is crucial for rock engineering design and analysis. Experimental studies have shown that confining pressure and plastic strain have significant influences on the post-peak strength and deformation characteristics of rock. A modified Hoek-Brown model has been proposed to describe the plastic-strain-dependent post-peak strength of rock.
ROCK MECHANICS AND ROCK ENGINEERING
(2023)
Article
Engineering, Geological
Zhengming Yang, Shuai Xu, Hao Zhang, Wenzhi Guo, Ming Cai
Summary: A new rockbolt called 2S-bolt has been developed for rock support in deep underground engineering. It consists of a threadbar, sliding piston, sliding-resistance cone pipe, anchorage section, plate, and plate-nut. The bolt's deformation occurs through frictional sliding and steel stretching in different deformation stages. Laboratory studies and pull-out tests were conducted to evaluate the performance of the bolt. The results showed that the 2S-bolt could absorb a large amount of energy at higher load capacities, making it suitable for rock support in rockbursting and squeezing grounds.
ROCK MECHANICS AND ROCK ENGINEERING
(2023)