Pub Date : 2025-12-11DOI: 10.1016/j.ijrmms.2025.106368
L.F. Fan, M.Z. Ye, Q.H. Yang, X.L. Du
This paper presents a method for determining the mechanical properties of nonlinear joints using deep learning-based analysis of wavelet time–frequency spectrograms. First, the stress wave signals of nonlinear joints are processed through wavelet analysis to generate time–frequency spectrograms, which capture complex energy distributions in both time and frequency domains. Subsequently, a convolutional neural network (CNN) model is constructed to analyze these spectrograms and establish a mapping relationship between the time–frequency features and the mechanical properties of the joints, which enables intelligent identification of the mechanical characteristics of nonlinear joints. Finally, the predictive performance of the deep learning method is validated by comparing the estimated values of initial joint stiffness and maximum allowable closure with their theoretical counterparts. The results demonstrate that the improved CNN model can be quickly obtained after 10 iterations. The proposed method can effectively predict the mechanical properties (initial joint stiffness and maximum allowable closure) of nonlinear joints from reflected wavelet signals, with relative errors of less than 3.5 % and 3.0 %, respectively. The study confirms the feasibility and effectiveness of this approach for predicting the mechanical properties of nonlinear joints.
{"title":"A method for mechanical properties identification of nonlinear joints based on deep learning in time-frequency domain","authors":"L.F. Fan, M.Z. Ye, Q.H. Yang, X.L. Du","doi":"10.1016/j.ijrmms.2025.106368","DOIUrl":"10.1016/j.ijrmms.2025.106368","url":null,"abstract":"<div><div>This paper presents a method for determining the mechanical properties of nonlinear joints using deep learning-based analysis of wavelet time–frequency spectrograms. First, the stress wave signals of nonlinear joints are processed through wavelet analysis to generate time–frequency spectrograms, which capture complex energy distributions in both time and frequency domains. Subsequently, a convolutional neural network (CNN) model is constructed to analyze these spectrograms and establish a mapping relationship between the time–frequency features and the mechanical properties of the joints, which enables intelligent identification of the mechanical characteristics of nonlinear joints. Finally, the predictive performance of the deep learning method is validated by comparing the estimated values of initial joint stiffness and maximum allowable closure with their theoretical counterparts. The results demonstrate that the improved CNN model can be quickly obtained after 10 iterations. The proposed method can effectively predict the mechanical properties (initial joint stiffness and maximum allowable closure) of nonlinear joints from reflected wavelet signals, with relative errors of less than 3.5 % and 3.0 %, respectively. The study confirms the feasibility and effectiveness of this approach for predicting the mechanical properties of nonlinear joints.</div></div>","PeriodicalId":54941,"journal":{"name":"International Journal of Rock Mechanics and Mining Sciences","volume":"198 ","pages":"Article 106368"},"PeriodicalIF":7.5,"publicationDate":"2025-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145731626","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Understanding fragmentation and energy dissipation during rockfall events is essential for accurate hazard assessment and predictive modelling. To date, most experimental studies have used spherical specimens, primarily because of their geometric simplicity and ease of repeatable testing. This work investigates the dynamic behaviour of angular block shapes, i.e., cubes, prisms, and slabs, which more closely resemble natural rock geometries, through free-fall drop tests up to , complemented by static splitting tests to explore potential links with dynamic response. These geometries often result in non-collinear impacts with multiple contact points and prolonged impact durations, significantly influencing the likelihood of fragmentation and post-impact dynamics. The study examines how block geometry, impact orientation and location (face, edge, vertex) affect failure patterns and energy restitution. Results show that fragmentation probability strongly depends on geometry: slabs fragmented in 33% of tests, prisms in 50%, while cubes only at the highest velocity. Static tests revealed geometry- and loading condition- dependent tensile strength, with prisms showing the highest median value () and slabs the lowest (). Fragmentation severity also varied, with slabs producing finer fragments compared to prisms. For intact specimens, apparent restitution coefficients ranged from 0.13 (prisms) to 0.39 (cubes), significantly lower than spheres (), and impact durations were up to two orders of magnitude longer than for spherical blocks. The results highlight the complex interplay between block geometry, impact conditions, and energy dissipation, providing shape-dependent metrics for improving rockfall trajectory models.
{"title":"Fragmentation and energy dissipation in rockfall: Effects of block shape and non-collinear impact dynamics","authors":"Maddalena Marchelli , Davide Ettore Guccione , Anna Giacomini , Olivier Buzzi","doi":"10.1016/j.ijrmms.2025.106381","DOIUrl":"10.1016/j.ijrmms.2025.106381","url":null,"abstract":"<div><div>Understanding fragmentation and energy dissipation during rockfall events is essential for accurate hazard assessment and predictive modelling. To date, most experimental studies have used spherical specimens, primarily because of their geometric simplicity and ease of repeatable testing. This work investigates the dynamic behaviour of angular block shapes, i.e., cubes, prisms, and slabs, which more closely resemble natural rock geometries, through free-fall drop tests up to <span><math><mrow><mn>10</mn><mspace></mspace><mtext>m/s</mtext></mrow></math></span>, complemented by static splitting tests to explore potential links with dynamic response. These geometries often result in non-collinear impacts with multiple contact points and prolonged impact durations, significantly influencing the likelihood of fragmentation and post-impact dynamics. The study examines how block geometry, impact orientation and location (face, edge, vertex) affect failure patterns and energy restitution. Results show that fragmentation probability strongly depends on geometry: slabs fragmented in 33% of tests, prisms in 50%, while cubes only at the highest velocity. Static tests revealed geometry- and loading condition- dependent tensile strength, with prisms showing the highest median value (<span><math><mrow><mo>≈</mo><mn>2</mn><mo>.</mo><mn>3</mn><mspace></mspace><mtext>MPa</mtext></mrow></math></span>) and slabs the lowest (<span><math><mrow><mo>≈</mo><mn>1</mn><mo>.</mo><mn>1</mn><mspace></mspace><mtext>MPa</mtext></mrow></math></span>). Fragmentation severity also varied, with slabs producing finer fragments compared to prisms. For intact specimens, apparent restitution coefficients ranged from 0.13 (prisms) to 0.39 (cubes), significantly lower than spheres (<span><math><mrow><mo>≈</mo><mn>0</mn><mo>.</mo><mn>34</mn></mrow></math></span>), and impact durations were up to two orders of magnitude longer than for spherical blocks. The results highlight the complex interplay between block geometry, impact conditions, and energy dissipation, providing shape-dependent metrics for improving rockfall trajectory models.</div></div>","PeriodicalId":54941,"journal":{"name":"International Journal of Rock Mechanics and Mining Sciences","volume":"198 ","pages":"Article 106381"},"PeriodicalIF":7.5,"publicationDate":"2025-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145732437","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-10DOI: 10.1016/j.ijrmms.2025.106362
Meng Meng , Marcus Wigand , Luke P. Frash , Mohmad M. Thakur , Qiquan Xiong , Nathan J. Welch , Wenfeng Li , James W. Carey
Understanding and quantifying subsurface fluid flow in fractures is essential for predicting hydrocarbon transport in unconventional reservoirs. Current shale oil and gas extraction methods recover only 10–20 % of resources due to limited understanding of coupled geomechanical and fluid flow processes. To improve production strategies, we developed a high-pressure “quad-pore” triaxial cell that enables real-time, lab-scale monitoring of oil and gas production during in-situ fracturing under reservoir conditions, providing time-resolved measurements of fluid flow and transport properties throughout the experiment. Using Wolfcamp shale saturated with live oil, we created fractures at in situ stresses, and then quantified fracture permeability and fluid production throughout surfactant-brine soaking, pore pressure drawdown, and long term production. Combined with post-testing characterization using CT-scanning and thin section analysis, our results show that in situ fracturing with pressure drawdown below the saturation equilibrium pressure contributes to methane production. Complex fresh fractures with larger surface areas yield higher gas production, and a similar produced gas over surface area ratio, 0.42–0.79, was found for same testing conditions. Compared to overnight soaking, the longer soaking period of 3 days doubles the penetration depth into rock matrix, from 0.22 ± 0.17 mm to 0.35 ± 0.18 mm, and enhances hydrocarbon production by specifically increasing the produced gas over surface area ratio to 0.78–1.2. Additionally, we identified flow hindrance from solid particle filtration that could be remediated by temporarily halting or reversing flow. Overall, our experimental work provides key evidence and understanding for hydrocarbon flow mechanisms in unconventional shale, which promote hydrocarbon production.
{"title":"A novel hydro-mechanical-chemical coupled experiment for unconventional hydrocarbon production evaluation","authors":"Meng Meng , Marcus Wigand , Luke P. Frash , Mohmad M. Thakur , Qiquan Xiong , Nathan J. Welch , Wenfeng Li , James W. Carey","doi":"10.1016/j.ijrmms.2025.106362","DOIUrl":"10.1016/j.ijrmms.2025.106362","url":null,"abstract":"<div><div>Understanding and quantifying subsurface fluid flow in fractures is essential for predicting hydrocarbon transport in unconventional reservoirs. Current shale oil and gas extraction methods recover only 10–20 % of resources due to limited understanding of coupled geomechanical and fluid flow processes. To improve production strategies, we developed a high-pressure “quad-pore” triaxial cell that enables real-time, lab-scale monitoring of oil and gas production during in-situ fracturing under reservoir conditions, providing time-resolved measurements of fluid flow and transport properties throughout the experiment. Using Wolfcamp shale saturated with live oil, we created fractures at in situ stresses, and then quantified fracture permeability and fluid production throughout surfactant-brine soaking, pore pressure drawdown, and long term production. Combined with post-testing characterization using CT-scanning and thin section analysis, our results show that in situ fracturing with pressure drawdown below the saturation equilibrium pressure contributes to methane production. Complex fresh fractures with larger surface areas yield higher gas production, and a similar produced gas over surface area ratio, 0.42–0.79, was found for same testing conditions. Compared to overnight soaking, the longer soaking period of 3 days doubles the penetration depth into rock matrix, from 0.22 ± 0.17 mm to 0.35 ± 0.18 mm, and enhances hydrocarbon production by specifically increasing the produced gas over surface area ratio to 0.78–1.2. Additionally, we identified flow hindrance from solid particle filtration that could be remediated by temporarily halting or reversing flow. Overall, our experimental work provides key evidence and understanding for hydrocarbon flow mechanisms in unconventional shale, which promote hydrocarbon production.</div></div>","PeriodicalId":54941,"journal":{"name":"International Journal of Rock Mechanics and Mining Sciences","volume":"198 ","pages":"Article 106362"},"PeriodicalIF":7.5,"publicationDate":"2025-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145730769","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-10DOI: 10.1016/j.ijrmms.2025.106363
ZiHan Zhang , Hao Yu , Bo Li , Wei Cheng , JiaPing Tao , SiWei Meng , He Liu , HengAn Wu
Carbon dioxide (CO2) phase change fracturing technology generates a massive amount of energy through the phase change of injected fluid in a short period, where the fluid is extruded into the rock formation to drive the fracture propagation. Apart from the rock inertia effect during fracturing, fracture instability could be seen at the crack tip due to a significant phase changing fluid infiltration, which is often ignored in previous models. This work develops a multi-processes phase-field framework for CO2 phase change fracturing in rock formations. The phase changing effect for non-equilibrium multi-phase flow is coupled by modifying mass and energy conservation equations where the Vesovic model is utilized to accurately capture the transport properties of CO2 and the fluid infiltration. G-criterion correlated to the pore pressure gradient is introduced to describe rock strength degeneration caused by fluid infiltration, which destabilizes the fracture propagation. The model is validated against the experimental and theoretical results. Four different fracturing methods (water-based fracturing, CO2 fracturing, blasting fracturing, and CO2 phase change fracturing) are carefully analyzed, indicating that CO2 phase change fracturing generates multi-level branches while increasing the stimulated reservoir volume compared with water-based/CO2 fracturing. Different from blasting fracturing, the branching in CO2 phase change fracturing is mode II fracture caused by the fluid infiltration with weaker inertia effects rather than mode I dynamic fracture. The influences of different formation parameters on fracturing behaviors are further discussed, which provides theoretical guidance for engineering applications of CO2 phase change fracturing technology.
{"title":"A multi-processes phase-field model for CO2 phase change fracturing","authors":"ZiHan Zhang , Hao Yu , Bo Li , Wei Cheng , JiaPing Tao , SiWei Meng , He Liu , HengAn Wu","doi":"10.1016/j.ijrmms.2025.106363","DOIUrl":"10.1016/j.ijrmms.2025.106363","url":null,"abstract":"<div><div>Carbon dioxide (CO<sub>2</sub>) phase change fracturing technology generates a massive amount of energy through the phase change of injected fluid in a short period, where the fluid is extruded into the rock formation to drive the fracture propagation. Apart from the rock inertia effect during fracturing, fracture instability could be seen at the crack tip due to a significant phase changing fluid infiltration, which is often ignored in previous models. This work develops a multi-processes phase-field framework for CO<sub>2</sub> phase change fracturing in rock formations. The phase changing effect for non-equilibrium multi-phase flow is coupled by modifying mass and energy conservation equations where the Vesovic model is utilized to accurately capture the transport properties of CO<sub>2</sub> and the fluid infiltration. G-criterion correlated to the pore pressure gradient is introduced to describe rock strength degeneration caused by fluid infiltration, which destabilizes the fracture propagation. The model is validated against the experimental and theoretical results. Four different fracturing methods (water-based fracturing, CO<sub>2</sub> fracturing, blasting fracturing, and CO<sub>2</sub> phase change fracturing) are carefully analyzed, indicating that CO<sub>2</sub> phase change fracturing generates multi-level branches while increasing the stimulated reservoir volume compared with water-based/CO<sub>2</sub> fracturing. Different from blasting fracturing, the branching in CO<sub>2</sub> phase change fracturing is mode II fracture caused by the fluid infiltration with weaker inertia effects rather than mode I dynamic fracture. The influences of different formation parameters on fracturing behaviors are further discussed, which provides theoretical guidance for engineering applications of CO<sub>2</sub> phase change fracturing technology.</div></div>","PeriodicalId":54941,"journal":{"name":"International Journal of Rock Mechanics and Mining Sciences","volume":"198 ","pages":"Article 106363"},"PeriodicalIF":7.5,"publicationDate":"2025-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145731628","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-09DOI: 10.1016/j.ijrmms.2025.106365
Yue Cui , Yingchun Li , Yang Xu
Prediction of the normal deformation of natural rock joints has long been a burning and thorny issue covering several important fields including rock mechanics, geophysics and hydrogeology. A key barrier preventing our accurate quantification towards the joint normal deformability lies in the complex interaction between two random, multi-scale rough surfaces. Classic multi-asperity contact models (e.g., Greenwood and Williamson, 1966) are based on statistical distribution with Hertz contact theory and simply assumed single-scale contacting asperities of identical shape and thus overlooked mechanical interactions of random asperities spanning a wide spectrum of geometrical scales. Here we first applied Persson's theory (Persson, 2001a), a multi-scale rough surface contact model based on the stochastic process theory, to derive the analytical normal stress-closure relationship of rough-walled joints. The core strengths of this theory include (1) quantitative description of geometric properties of multi-scale roughness via power spectral density; (2) stochastic interpretation of evolutions of roughness contact and commensurate local contact pressure; (3) stochastic modeling of asperity interaction across multiple scales; and (4) derivation of the global normal stress-deformation relationship driven by the conservation of elastic energy stored over the contact area variation of deformed multi-scale roughness. Comparisons between analytical solutions and experimental measurements on eight pairs of rough rock joints demonstrated the robust performance of Persson's theory in predicting the normal stress-closure relationship of both matched and mismatched joint walls. Our study may offer an alternative paradigm for pertinent academic communities to interpret the empirical semi-logarithmic rule and multi-scale nature of the normal deformability of natural rock joints.
天然岩石节理法向变形预测一直是岩石力学、地球物理和水文地质学等多个重要领域的热点和难点问题。阻碍我们准确量化关节法向变形能力的一个关键障碍在于两个随机、多尺度粗糙表面之间的复杂相互作用。经典的多粗糙体接触模型（如Greenwood和Williamson， 1966）基于赫兹接触理论的统计分布，简单地假设了形状相同的单尺度接触粗糙体，从而忽略了跨越广泛几何尺度的随机粗糙体的力学相互作用。本文首先应用基于随机过程理论的多尺度粗糙面接触模型Persson’s theory (Persson, 2001a)，推导了粗糙壁节理的解析法向应力闭合关系。该理论的核心优势包括：(1)通过功率谱密度定量描述多尺度粗糙度的几何性质；(2)粗糙接触演化和相应局部接触压力的随机解释；(3)多尺度粗糙相互作用的随机模拟；(4)推导了基于变形多尺度粗糙度接触面积变化的弹性能量守恒驱动的全局法向应力-变形关系。通过对8对粗糙岩石节理的解析解和实验测量结果的比较，证明了Persson理论在预测匹配和不匹配节理壁的正常应力闭合关系方面的强大性能。本研究可为相关学术界解释天然岩石节理法向可变形性的经验半对数规律和多尺度性质提供另一种范式。
{"title":"Normal deformability of rough rock joints – a predictive analytical model based on Persson's theory of contact","authors":"Yue Cui , Yingchun Li , Yang Xu","doi":"10.1016/j.ijrmms.2025.106365","DOIUrl":"10.1016/j.ijrmms.2025.106365","url":null,"abstract":"<div><div>Prediction of the normal deformation of natural rock joints has long been a burning and thorny issue covering several important fields including rock mechanics, geophysics and hydrogeology. A key barrier preventing our accurate quantification towards the joint normal deformability lies in the complex interaction between two random, multi-scale rough surfaces. Classic multi-asperity contact models (e.g., Greenwood and Williamson, 1966) are based on statistical distribution with Hertz contact theory and simply assumed single-scale contacting asperities of identical shape and thus overlooked mechanical interactions of random asperities spanning a wide spectrum of geometrical scales. Here we first applied Persson's theory (Persson, 2001a), a multi-scale rough surface contact model based on the stochastic process theory, to derive the analytical normal stress-closure relationship of rough-walled joints. The core strengths of this theory include (1) quantitative description of geometric properties of multi-scale roughness via power spectral density; (2) stochastic interpretation of evolutions of roughness contact and commensurate local contact pressure; (3) stochastic modeling of asperity interaction across multiple scales; and (4) derivation of the global normal stress-deformation relationship driven by the conservation of elastic energy stored over the contact area variation of deformed multi-scale roughness. Comparisons between analytical solutions and experimental measurements on eight pairs of rough rock joints demonstrated the robust performance of Persson's theory in predicting the normal stress-closure relationship of both matched and mismatched joint walls. Our study may offer an alternative paradigm for pertinent academic communities to interpret the empirical semi-logarithmic rule and multi-scale nature of the normal deformability of natural rock joints.</div></div>","PeriodicalId":54941,"journal":{"name":"International Journal of Rock Mechanics and Mining Sciences","volume":"198 ","pages":"Article 106365"},"PeriodicalIF":7.5,"publicationDate":"2025-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145731627","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Constructing numerical models based on real microstructures is fundamental for accurately capturing rock failure behaviour. Herein, a novel grain-based model with transverse isotropy (GBM-T) based on the bonded particle method is proposed to explore the intrinsic mechanism underlying the failure of transversely isotropic rocks at the grain scale. First, the mineral composition, grain size and grain shape of transversely isotropic gneiss are obtained, and the uniaxial compressive strength and Young's modulus of gneiss with different bedding plane angles are measured. A transformation algorithm is then applied to construct GBM-T, which considers realistic grain shape and complex bedding plane morphology. The mechanisms of different failure modes are analysed from the view of mineral-scale. Results indicate that the damage of gneiss with different bedding angles can be effectively reproduced using GBM-T. The deformation characteristics of rocks with horizontal bedding planes are dominated by intragranular tensile cracks, while tensile cracks propagating along grain boundaries have a significant impact on the fracture features of rocks with vertical bedding planes. Owing to the widespread occurrence of transversely isotropic rocks on the Earth's surface, GBM-T is expected to be applicable in the engineering fields, such as mining, tunnelling, shale gas extraction, salt cavern storage and slope protection, etc.
{"title":"Failure behaviour simulation of transversely isotropic rocks considering realistic grain structure and bedding plane morphology","authors":"Renjie Wu , Haibo Li , Guorui Feng , Yuxia Guo , Chong Yu","doi":"10.1016/j.ijrmms.2025.106369","DOIUrl":"10.1016/j.ijrmms.2025.106369","url":null,"abstract":"<div><div>Constructing numerical models based on real microstructures is fundamental for accurately capturing rock failure behaviour. Herein, a novel grain-based model with transverse isotropy (GBM-T) based on the bonded particle method is proposed to explore the intrinsic mechanism underlying the failure of transversely isotropic rocks at the grain scale. First, the mineral composition, grain size and grain shape of transversely isotropic gneiss are obtained, and the uniaxial compressive strength and Young's modulus of gneiss with different bedding plane angles are measured. A transformation algorithm is then applied to construct GBM-T, which considers realistic grain shape and complex bedding plane morphology. The mechanisms of different failure modes are analysed from the view of mineral-scale. Results indicate that the damage of gneiss with different bedding angles can be effectively reproduced using GBM-T. The deformation characteristics of rocks with horizontal bedding planes are dominated by intragranular tensile cracks, while tensile cracks propagating along grain boundaries have a significant impact on the fracture features of rocks with vertical bedding planes. Owing to the widespread occurrence of transversely isotropic rocks on the Earth's surface, GBM-T is expected to be applicable in the engineering fields, such as mining, tunnelling, shale gas extraction, salt cavern storage and slope protection, etc.</div></div>","PeriodicalId":54941,"journal":{"name":"International Journal of Rock Mechanics and Mining Sciences","volume":"198 ","pages":"Article 106369"},"PeriodicalIF":7.5,"publicationDate":"2025-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145689651","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-05DOI: 10.1016/j.ijrmms.2025.106367
Chuanrui Wang , Shouyi Xie , Jian-Fu Shao , Minh-Ngoc Vu , Christophe de Lesquen
The Callovo-Oxfordian (COx) claystone is investigated as host rock in the French project Cigeo for geological disposal of radioactive waste. Temperature rise due to heat emitted by radioactive waste is an important process to be considered. It is crucial to characterize effects of temperature change on the mechanical behavior of host rock. Despite previous studies, the issue is still open. This work presents a complementary study by performing a new series of triaxial compression tests. Six different values of temperature are considered ranging from 20 °C to 90 °C. The tests are performed under three different confining pressures. Elastic properties upon unloading–reloading paths and peak deviatoric stresses are evaluated for each test. It is found that the peak deviatoric stress of COx claystone is more affected by the temperature rise than the elastic properties. Scatters of experimental data are also investigated by comparing several tests performed under the same loading conditions. Finally, the thermal effects on the failure strength are evaluated by using a micromechanics-based criterion.
{"title":"On the thermal effects of mechanical behavior in the Callovo-Oxfordian claystone","authors":"Chuanrui Wang , Shouyi Xie , Jian-Fu Shao , Minh-Ngoc Vu , Christophe de Lesquen","doi":"10.1016/j.ijrmms.2025.106367","DOIUrl":"10.1016/j.ijrmms.2025.106367","url":null,"abstract":"<div><div>The Callovo-Oxfordian (COx) claystone is investigated as host rock in the French project Cigeo for geological disposal of radioactive waste. Temperature rise due to heat emitted by radioactive waste is an important process to be considered. It is crucial to characterize effects of temperature change on the mechanical behavior of host rock. Despite previous studies, the issue is still open. This work presents a complementary study by performing a new series of triaxial compression tests. Six different values of temperature are considered ranging from 20 °C to 90 °C. The tests are performed under three different confining pressures. Elastic properties upon unloading–reloading paths and peak deviatoric stresses are evaluated for each test. It is found that the peak deviatoric stress of COx claystone is more affected by the temperature rise than the elastic properties. Scatters of experimental data are also investigated by comparing several tests performed under the same loading conditions. Finally, the thermal effects on the failure strength are evaluated by using a micromechanics-based criterion.</div></div>","PeriodicalId":54941,"journal":{"name":"International Journal of Rock Mechanics and Mining Sciences","volume":"198 ","pages":"Article 106367"},"PeriodicalIF":7.5,"publicationDate":"2025-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145665696","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-02DOI: 10.1016/j.ijrmms.2025.106364
Timo Saksala , Mahmood Jabareen
The phase field method captures tensile (mode I) fracturing of brittle materials but has serious challenges in uniaxial compression of heterogeneous materials like rock and concrete. In this paper, we mend this drawback by combining a phase field model for mode I fracture with a viscoplastic damage model to capture the shear banding in uniaxial compression of rock. In the present phase field formulation, the mode I fracture is driven by Rankine type of crack driving force, while the Mohr–Coulomb criterion is employed in the viscoplastic damage part of the model to capture the compressive/shear failure. As the model is designed for transient dynamic problems, strain rate sensitivity of rock is accommodated, here by a linear viscous term in both the phase field and viscoplastic damage parts. The viscoplastic part is cast in the consistency format. The phase field variable and the damage variable operate, respectively, on the positive and negative parts of the principal stress returned to the (Mohr–Coulomb) yield surface. The performance of the model is demonstrated in uniaxial tension and compression tests. Finally, the dynamic Brazilian disc test and punch-through shear tests are simulated for further validation. The model captures the strain rate sensitive direct and indirect tensile strength as well as the correct failure modes in these tests.
{"title":"A combined viscoplastic damage-phase field model for rock fracture under dynamic loading","authors":"Timo Saksala , Mahmood Jabareen","doi":"10.1016/j.ijrmms.2025.106364","DOIUrl":"10.1016/j.ijrmms.2025.106364","url":null,"abstract":"<div><div>The phase field method captures tensile (mode I) fracturing of brittle materials but has serious challenges in uniaxial compression of heterogeneous materials like rock and concrete. In this paper, we mend this drawback by combining a phase field model for mode I fracture with a viscoplastic damage model to capture the shear banding in uniaxial compression of rock. In the present phase field formulation, the mode I fracture is driven by Rankine type of crack driving force, while the Mohr–Coulomb criterion is employed in the viscoplastic damage part of the model to capture the compressive/shear failure. As the model is designed for transient dynamic problems, strain rate sensitivity of rock is accommodated, here by a linear viscous term in both the phase field and viscoplastic damage parts. The viscoplastic part is cast in the consistency format. The phase field variable and the damage variable operate, respectively, on the positive and negative parts of the principal stress returned to the (Mohr–Coulomb) yield surface. The performance of the model is demonstrated in uniaxial tension and compression tests. Finally, the dynamic Brazilian disc test and punch-through shear tests are simulated for further validation. The model captures the strain rate sensitive direct and indirect tensile strength as well as the correct failure modes in these tests.</div></div>","PeriodicalId":54941,"journal":{"name":"International Journal of Rock Mechanics and Mining Sciences","volume":"197 ","pages":"Article 106364"},"PeriodicalIF":7.5,"publicationDate":"2025-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145657714","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-01DOI: 10.1016/j.ijrmms.2025.106359
Bruce Gee , Mengsu Hu , Michael Manga
Deep geologic repositories are a proposed solution to safely dispose of nuclear waste at the end its useful life. As the contents decay, heat is released into the surrounding subsurface, creating stress and driving heat and fluid transport. While it is not expected that a repository would be placed in an area with recent geologic activity, an induced seismic event could have significant detrimental effects on the integrity of the repository and safety of the public. Here we examine the frictional stability of both locked and aseismic creeping faults subjected to nuclear waste decay heating for both granite and argillite rock masses. The stress in the rock mass is evaluated numerically using a volumetric thermo-poro-elastic response and a deviatoric visco-elastic Burgers model. Thermally-dependent rate and state friction models are used to evaluate the frictional stability. The risk of induced seismicity is generally low, as only small perturbations to the factor of safety are induced by the heating. Both rock types have advantages, as the higher friction of granites creates greater factors of safety, while the creep of argillite reduces the thermal stresses. The in-situ conditions have the greatest effect on the risk of induced seismicity, and higher mean in-situ stresses and hydrostatic conditions lower the risks of inducing a seismic event. Faults undergoing aseismic creep are likely to experience an increase in their creep rate but appear unlikely to experience rupture. This analysis provides guidance in site selection to minimize the risk of induced seismicity when building a deep geologic repository.
{"title":"Evaluating the risk of induced seismicity in nuclear waste disposal","authors":"Bruce Gee , Mengsu Hu , Michael Manga","doi":"10.1016/j.ijrmms.2025.106359","DOIUrl":"10.1016/j.ijrmms.2025.106359","url":null,"abstract":"<div><div>Deep geologic repositories are a proposed solution to safely dispose of nuclear waste at the end its useful life. As the contents decay, heat is released into the surrounding subsurface, creating stress and driving heat and fluid transport. While it is not expected that a repository would be placed in an area with recent geologic activity, an induced seismic event could have significant detrimental effects on the integrity of the repository and safety of the public. Here we examine the frictional stability of both locked and aseismic creeping faults subjected to nuclear waste decay heating for both granite and argillite rock masses. The stress in the rock mass is evaluated numerically using a volumetric thermo-poro-elastic response and a deviatoric visco-elastic Burgers model. Thermally-dependent rate and state friction models are used to evaluate the frictional stability. The risk of induced seismicity is generally low, as only small perturbations to the factor of safety are induced by the heating. Both rock types have advantages, as the higher friction of granites creates greater factors of safety, while the creep of argillite reduces the thermal stresses. The in-situ conditions have the greatest effect on the risk of induced seismicity, and higher mean in-situ stresses and hydrostatic conditions lower the risks of inducing a seismic event. Faults undergoing aseismic creep are likely to experience an increase in their creep rate but appear unlikely to experience rupture. This analysis provides guidance in site selection to minimize the risk of induced seismicity when building a deep geologic repository.</div></div>","PeriodicalId":54941,"journal":{"name":"International Journal of Rock Mechanics and Mining Sciences","volume":"197 ","pages":"Article 106359"},"PeriodicalIF":7.5,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145651077","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-29DOI: 10.1016/j.ijrmms.2025.106358
Shupeng Chai , Yuan Zou , Huanyu Wu , Mohammadreza Akbariforouz , Boyang Su , Giovanni Grasselli , Derek Elsworth , Yossef H. Hatzor , Qi Zhao
Laboratory shear tests are widely used to investigate the evolution of first and second-order frictional behavior and rupture nucleation on rock discontinuities. Average stress across the sample, instead of spatial stress distributions, is typically assumed in analysis. We provide a thorough numerical investigation of eight common laboratory shear test configurations, considering a linear velocity-weakening friction law on a planar sliding surface, to quantify the temporal and spatial nonuniformity of stress both before shear and during stick-slip cycles. Our results indicate that non-uniform stress distribution resulting from the test configuration exists in all laboratory shear tests, with stress concentration occurring at the edges of the shear plane, while the stress in the central portion of laboratory faults remains almost uniform. Stress heterogeneity is more pronounced in direct shear than in inclined and rotary shear configurations. During stick-slip cycles, the local shear stress significantly dropped as the rupture front propagated through, resulting in a more uniform stress distribution in the slip phase than in the stick phase. Stress concentration near the sample edge governs the rupture process and the resulting localization of damage. These findings highlight the importance of considering stress heterogeneity in laboratory investigations of damage evaluation on rock discontinuities. We suggest that test configuration-related stress heterogeneity should be distinguished from surface roughness-induced stress heterogeneity, and utilizing average stress may lead to misinterpretation of the rupture dynamics and damage patterns. Our results provide a guide on quantitative analysis of the shear behavior of rock discontinuities, considering stress heterogeneity in laboratory experiments.
{"title":"Influence of stress heterogeneity on shear behavior of rock discontinuities in laboratory experiments: New insights from numerical simulations","authors":"Shupeng Chai , Yuan Zou , Huanyu Wu , Mohammadreza Akbariforouz , Boyang Su , Giovanni Grasselli , Derek Elsworth , Yossef H. Hatzor , Qi Zhao","doi":"10.1016/j.ijrmms.2025.106358","DOIUrl":"10.1016/j.ijrmms.2025.106358","url":null,"abstract":"<div><div>Laboratory shear tests are widely used to investigate the evolution of first and second-order frictional behavior and rupture nucleation on rock discontinuities. Average stress across the sample, instead of spatial stress distributions, is typically assumed in analysis. We provide a thorough numerical investigation of eight common laboratory shear test configurations, considering a linear velocity-weakening friction law on a planar sliding surface, to quantify the temporal and spatial nonuniformity of stress both before shear and during stick-slip cycles. Our results indicate that non-uniform stress distribution resulting from the test configuration exists in all laboratory shear tests, with stress concentration occurring at the edges of the shear plane, while the stress in the central portion of laboratory faults remains almost uniform. Stress heterogeneity is more pronounced in direct shear than in inclined and rotary shear configurations. During stick-slip cycles, the local shear stress significantly dropped as the rupture front propagated through, resulting in a more uniform stress distribution in the slip phase than in the stick phase. Stress concentration near the sample edge governs the rupture process and the resulting localization of damage. These findings highlight the importance of considering stress heterogeneity in laboratory investigations of damage evaluation on rock discontinuities. We suggest that test configuration-related stress heterogeneity should be distinguished from surface roughness-induced stress heterogeneity, and utilizing average stress may lead to misinterpretation of the rupture dynamics and damage patterns. Our results provide a guide on quantitative analysis of the shear behavior of rock discontinuities, considering stress heterogeneity in laboratory experiments.</div></div>","PeriodicalId":54941,"journal":{"name":"International Journal of Rock Mechanics and Mining Sciences","volume":"197 ","pages":"Article 106358"},"PeriodicalIF":7.5,"publicationDate":"2025-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145614045","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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