Article
Engineering, Geological
Erick Rogenes, Marcio Muniz de Farias, Leandro Lima Rasmussen
Summary: This paper presents a numerical model for representing the fracture process in hard rocks, validated through calibration with laboratory test results for Creighton granite. A sensitivity study led to the proposal of a calibration methodology to facilitate future use of the CVBM.
INTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS
(2022)
Article
Geosciences, Multidisciplinary
Lei Wu, Guoqing Chen, Jingfang Xing, Zhiyi Lin
Summary: This paper investigates the brittle cataclastic process of fault rocks, focusing on the structural evolution and mechanical behavior. A large-displacement direct shear model is proposed to simulate the process. The results indicate that the reduction in friction coefficient is caused by the crushing and rounding of rock fragments.
JOURNAL OF STRUCTURAL GEOLOGY
(2022)
Article
Chemistry, Multidisciplinary
Haozhe Liang, Xiaozu Fang, Xinlu Yu, Yingqian Fu, Gangyi Zhou
Summary: In this study, the real-time tensile mechanical and fracture behaviors of concrete were investigated under concentrated and distributed boundary conditions using the Brazilian test. The digital image correlation method was used to evaluate the tensile strength and failure process. The results showed that the crack initiation occurred randomly at the center and boundary in Brazilian tests with concentrated loads, while it mainly occurred at the center in tests with distributed loads.
APPLIED SCIENCES-BASEL
(2023)
Article
Engineering, Geological
Gabriel Walton, Steven Gaines, Leandro R. Alejano
Summary: This study examined the potential use of continuous-failure-state testing to constrain the residual strength envelope of rocks, finding that the data obtained from this method were consistent with traditional residual strength data. The primary factor limiting accurate characterization of residual strength for a given rock type is the variety of specimens available, rather than the amount of data for a single specimen. Therefore, continuous-failure-state testing is recommended only when the number of specimens available for testing is very limited.
JOURNAL OF ROCK MECHANICS AND GEOTECHNICAL ENGINEERING
(2021)
Article
Geochemistry & Geophysics
Michael J. Braunagel, W. Ashley Griffith
Summary: Fracture initiation and growth in rocks is a complex process that is influenced by grain-scale heterogeneity and changing stress states under dynamic loading conditions. Both crystalline and granular rocks exhibit similar fracture behaviors as engineered materials, such as rate-dependent fracture initiation toughness and a relationship between propagation toughness and crack velocity. However, the measured propagation toughness in rocks is higher than quasi-static values at lower crack velocities. Additionally, mixed mode crack propagation is fundamentally different between granite and sandstone due to grain scale controls on the fracture process.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2022)
Article
Geochemistry & Geophysics
Auriol S. P. Rae, Thomas Kenkmann, Vivek Padmanabha, Michael H. Poelchau, Frank Schaefer, Matthias A. Doerfler, Louis Mueller
Summary: Brittle deformation at high strain rates can cause fragmentation and pulverisation of rocks. The characteristic strain rates for rate-dependent brittle failure range from 150 to 300 s(-1) in the investigated lithologies. There is an empirical inverse power-law relationship between fragment size and strain rate, while fragment shape is independent of strain rate.
Article
Engineering, Geological
Xiaozhao Li, Huaiwei Yan, Xing Che
Summary: A novel micromechanics-based model for brittle rocks undergoing confined tensile fracture is proposed, based on the stress intensity factor of crack under different loading modes in fracture mechanics theory. The model considers both frictional and non-frictional confined tensile fracture mechanisms and investigates the transition process from the latter to the former. The stress-strain relationship during the confined tensile fracture, involving the unloading of axial stress in a compressive state and the loading of axial stress in a tensile state, is also studied. The model's validity is demonstrated through comparison with experimental data, and the effects of friction, density, inclination angle and size of the initial crack, and confining pressure on various mechanical properties of confined tensile fracture are discussed.
INTERNATIONAL JOURNAL OF GEOMECHANICS
(2023)
Article
Geochemistry & Geophysics
Christopher Harbord, Nicolas Brantut, David Wallis
Summary: The study investigates the influence of grain size on the rheological behavior of calcite aggregates in the semi-brittle regime. Compressive triaxial deformation tests are conducted on different rocks with varying grain sizes. The results show that both strength and hardening rate increase with decreasing grain size, and flow stress scales with the inverse of grain size. Microstructural observations reveal high twin densities in deformed samples, which increase with stress. The effect of twins on dislocation accumulation and hardening rate is likely smaller than the effect of grain size.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2023)
Article
Engineering, Geological
Seyed Davoud Mohammadi, Seyed Hossein Jalali, Nikoo Tavassoli Layen
Summary: Friction-transfer test can estimate the engineering properties of rocks, such as uniaxial compressive strength (UCS) and Brazilian tensile strength (BTS). The study found that there is a strong correlation between porosity and friction-transfer value and torsion angle. The relatively high coefficients of determination indicate that friction transfer can successfully predict the UCS of rocks.
ROCK MECHANICS AND ROCK ENGINEERING
(2022)
Article
Mechanics
Hadi Fathipour-Azar
Summary: This paper presents a data-oriented computational approach for predicting Mohr-Coulomb shear strength parameters. By utilizing a published database and random forest, alternating model tree, and support vector machine techniques, the shear strength parameters of sandstone rock were successfully predicted. The results showed that confining stress had a significant influence on prediction accuracy.
ARCHIVE OF APPLIED MECHANICS
(2022)
Article
Multidisciplinary Sciences
Mengze Yang, Houxu Huang, Yu Yang
Summary: This study verifies the phenomenon of tensile failure in rocks under static loading through experiments on red sandstone at different loading rates and analysis of surface deformation fields. The derived expression for effective tensile stress during crack propagation contributes to geotechnical engineering disaster warning.
SCIENTIFIC REPORTS
(2022)
Article
Geochemistry & Geophysics
Yves Bernabe, Matej Pec
Summary: This study proposes a reformulation of the wing crack model for understanding brittle creep and failure in rocks. The model takes into account the complex mechanical interactions of sliding and tensile wing cracks and suggests that these interactions lead to the formation of micro shear bands, which in turn affect the overall behavior of the rock. The study found that the proposed model is consistent with published creep and failure data, and can also estimate the cohesion and angle of internal friction in materials.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2022)
Article
Engineering, Mechanical
Qibin Lin, Ping Cao, Yinzhu Liu, Rihong Cao, Jiangteng Li
Summary: This study investigated the failure behavior and crack coalescence mechanism of jointed rock mass with a hole under compression-shear conditions through experiments and numerical modeling. The results showed that the peak load initially increased and then decreased with the increase in joint inclination angle, with various types of crack coalescence observed. The analysis of displacement fields further supported the experimental and simulation results.
THEORETICAL AND APPLIED FRACTURE MECHANICS
(2021)
Article
Engineering, Geological
Sana Zafar, Ahmadreza Hedayat, Omid Moradian
Summary: Time-dependent rock deformation leads to the weakening of rock mass. Understanding the fracturing mechanisms involved in the time-dependent behavior in brittle rocks is important. In this study, a series of experiments were conducted to analyze the spatial and temporal evolution of cracking mechanisms using AE and 2D-DIC techniques.
ROCK MECHANICS AND ROCK ENGINEERING
(2022)
Article
Engineering, Mechanical
Mengze Yang, Houxu Huang, Yu Yang
Summary: This study investigates the damage and fracture of brittle rock under long-term static loading, proposing a new expression for predicting rock durability based on the total time for microcrack propagation, and analyzing the relationship between the durability index and rock type.
THEORETICAL AND APPLIED FRACTURE MECHANICS
(2021)
Article
Mechanics
Xiaozhao Li, Zhushan Shao, Chengzhi Qi
ENGINEERING FRACTURE MECHANICS
(2020)
Article
Engineering, Mechanical
Xiaozhao Li, Chengzhi Qi, Pengchong Zhang
INTERNATIONAL JOURNAL OF FATIGUE
(2020)
Article
Geosciences, Multidisciplinary
Xiaozhao Li, Chengzhi Qi, Liren Ban, Zhushan Shao
Summary: The study highlights the influence of external loading paths on shear fracture induced by subcritical crack growth in brittle rocks under lithospheric conditions, as well as the evolution of rock shear properties. By introducing a novel micromechanical method and analyzing the historical stress function, the evolution of cohesion, shear strength, and internal friction angle during shear fracture induced by subcritical crack growth is revealed.
MATHEMATICAL GEOSCIENCES
(2021)
Article
Engineering, Mechanical
Xiaozhao Li, Chao Ma, Chengzhi Qi, Zhushan Shao
THEORETICAL AND APPLIED FRACTURE MECHANICS
(2020)
Article
Materials Science, Multidisciplinary
Xiaozhao Li, Xiaolei Qu, Chengzhi Qi, Zhushan Shao
INTERNATIONAL JOURNAL OF DAMAGE MECHANICS
(2020)
Article
Mining & Mineral Processing
Liren Ban, Weisheng Du, Tianwei Jin, Chengzhi Qi, Xiaozhao Li
Summary: This study proposed a reasonable roughness parameter to reflect the PSS of rock joints and developed a new PSS model, which was validated to be suitable for different types of rock joints except for gneiss joints. The model has the form of the Mohr-Coulomb model, revealing the relationship between 3D roughness parameters and the peak dilation angle.
INTERNATIONAL JOURNAL OF MINING SCIENCE AND TECHNOLOGY
(2021)
Article
Materials Science, Multidisciplinary
Xiaozhao Li, Chengzhi Qi
Summary: The study focused on the micromechanics-based tensile creep fracture behavior and presented a method for predicting direct tensile creep fractures. This method combines the suggested expression of mode-I stress intensity factor, subcritical crack growth law, and the relationship between wing crack length and axial strain. The rationality of the proposed tensile creep fracture model was verified by comparing with experimental results.
ACTA MECHANICA SOLIDA SINICA
(2022)
Article
Mechanics
Xiaozhao Li, Yaxing Jia, Qishuo Zhang, Chengzhi Qi
Summary: A micro-macro model is proposed to predict the effect of high pore pressure on shear failure properties of brittle rocks under triaxial compressive loadings. The model takes into account the pore pressure effect on microcrack growth, and combines the damage relation and the Mohr-Coulomb failure model. The results show that both pore pressure and confining pressure significantly influence the axial peak strength, axial peak strain, shear failure plane angle, shear strength, cohesion, and internal friction angle of the rocks, all of which decrease non-linearly with increasing pore pressure.
ARCHIVE OF APPLIED MECHANICS
(2022)
Article
Engineering, Mechanical
Chengzhi Qi, Fayuan Yan, Fa Zhao, Xiaozhao Li, Haoxiang Chen
Summary: Grady's energy-horizon theory of dynamic fragmentation (EHTDF) is reviewed and a new approach for determining the related dynamic fragmentation length scales is proposed. The study combines energy-based criteria and static size effect law with the relation between dynamic strength, strain rate, and fragment size obtained from the Maxwell model of rock deformation and fracture. The comparison between theoretical predictions and experimental measurements validates the proposed approach.
INTERNATIONAL JOURNAL OF IMPACT ENGINEERING
(2022)
Article
Energy & Fuels
Xiaozhao Li, Xing Che, Huaiwei Yan, Chengzhi Qi
Summary: A micro-macro method for evaluating direct tensile fractures in brittle rocks during progressive loadings is proposed. The method includes an equation for the stress intensity factor of the crack, as well as an expression for axial strain. The reasonableness of the method is proven through comparing published results. The sensitivity of initial crack properties on stress-strain curves, crack length curves, tensile strength, crack initiation stress, and elastic modulus is determined. The calculated results are important for the safety evaluation of surrounding rocks in deep-buried underground engineering.
GEOMECHANICS AND GEOPHYSICS FOR GEO-ENERGY AND GEO-RESOURCES
(2022)
Article
Engineering, Geological
Chengzhi Qi, Mingyang Wang, Zefan Wang, Xiaozhao Li
Summary: This paper studies the coupling effect of sample size and strain rate on the compressive strength of rock and proposes a unified theoretical model. In the quasi-static loading regime, the formula for the coupling effect of sample size and strain rate on rock strength is obtained. In the dynamic loading regime, the formula for the coupling effect of sample size and strain rate on rock compressive strength is determined.
ROCK MECHANICS AND ROCK ENGINEERING
(2023)
Article
Engineering, Geological
Xiaozhao Li, Huaiwei Yan, Xing Che
Summary: A novel micromechanics-based model for brittle rocks undergoing confined tensile fracture is proposed, based on the stress intensity factor of crack under different loading modes in fracture mechanics theory. The model considers both frictional and non-frictional confined tensile fracture mechanisms and investigates the transition process from the latter to the former. The stress-strain relationship during the confined tensile fracture, involving the unloading of axial stress in a compressive state and the loading of axial stress in a tensile state, is also studied. The model's validity is demonstrated through comparison with experimental data, and the effects of friction, density, inclination angle and size of the initial crack, and confining pressure on various mechanical properties of confined tensile fracture are discussed.
INTERNATIONAL JOURNAL OF GEOMECHANICS
(2023)
Article
Mechanics
Xiaozhao Li, Bocong Chai, Chengzhi Qi, Artem A. Kunitskikh, Evgenii V. Kozhevnikov
Summary: The thermal treatment temperature has a significant effect on the microcrack growth and shear fracture properties of brittle solids under compression. An analytical model is proposed to evaluate this effect, including a micro-macro model, functions for initial damage and fracture toughness versus temperature, and the Mohr-Coulomb strength criterion. The model provides important theoretical help for the engineering evaluation of brittle solids.
ARCHIVE OF APPLIED MECHANICS
(2023)
Article
Engineering, Geological
Li Xiao-zhao, Ban Li-ren, Qi Cheng-zhi
ROCK AND SOIL MECHANICS
(2020)
Article
Astronomy & Astrophysics
Qi ChengZhi, Xia Chen, Li XiaoZhao, Qu XiaoLei
SCIENTIA SINICA-PHYSICA MECHANICA & ASTRONOMICA
(2020)
