Pub Date : 2025-11-21DOI: 10.1016/j.ijrmms.2025.106351
Yi Qiu , Tianshou Ma , Kai Liang , Jiuxin Li , Yang Liu , P.G. Ranjith
To predict the long-term evolution of pore pressure and wellbore stability in shale formations, it is essential to understand the hydro-chemical coupling in anisotropic and chemically active shales. However, characterizing these processes in anisotropic shales remains a significant challenge. Traditional pressure transmission testing (PTT) is primarily designed for isotropic materials and relies solely on downstream pressure data, which provides an incomplete characterization and fails to capture the internal spatiotemporal evolution of pore pressure in anisotropic media. Moreover, the parameter inversion process in traditional methods is often regarded as a "black-box" process, providing limited transparency and interpretability. Therefore, this study developed an integrated experimental PTT system and numerical inversion framework. Firstly, a novel multi-point PTT system equipped with three axially distributed pressure sensors was developed to directly monitor the internal pore pressure evolution. The hydraulic/chemical loading procedure was designed to measure the pressure transmission behavior of anisotropic Longmaxi shale. Next, an anisotropic hydraulic-chemical coupling model was developed based on extended chemo-poroelastic theory, and a grid search-based inversion framework was further implemented to estimate the hydro-chemical coupling parameters of anisotropic shale. Then, the multi-point pressure response was examined for anisotropic Longmaxi shale, and the anisotropic permeability, solute diffusion, and reflection coefficients were inverted. Finally, the merits of multi-point PTT compared to single-point PTT were thoroughly examined. Furthermore, the conventional PTT results of the Pierre II and Ghom shales were benchmarked, and the implications for wellbore stability were thoroughly discussed. The results indicated that the Longmaxi shale exhibited significant anisotropy, with anisotropic ratios of 6.12, 8.33, and 1.38 for the permeability, diffusion, and reflection coefficients, respectively. The maximum and average relative errors of the inversion results based on the multi-point PTT results are 12.1 % and 2.56 %, respectively, which are 5.1 % and 0.71 % lower than those of traditional single-point PTT method. The grid search-based inversion framework was further validated by published datasets of both the Pierre II and the Ghom shales. This work demonstrated the efficacy of multi-point PTT system and transparent inversion framework for characterizing hydro-chemical coupling behavior of anisotropic shale and offering valuable implications for shale wellbore stability.
{"title":"Multi-point pressure transmission testing and transparent inversion of hydro-chemical coupling parameters on anisotropic shale","authors":"Yi Qiu , Tianshou Ma , Kai Liang , Jiuxin Li , Yang Liu , P.G. Ranjith","doi":"10.1016/j.ijrmms.2025.106351","DOIUrl":"10.1016/j.ijrmms.2025.106351","url":null,"abstract":"<div><div>To predict the long-term evolution of pore pressure and wellbore stability in shale formations, it is essential to understand the hydro-chemical coupling in anisotropic and chemically active shales. However, characterizing these processes in anisotropic shales remains a significant challenge. Traditional pressure transmission testing (PTT) is primarily designed for isotropic materials and relies solely on downstream pressure data, which provides an incomplete characterization and fails to capture the internal spatiotemporal evolution of pore pressure in anisotropic media. Moreover, the parameter inversion process in traditional methods is often regarded as a \"black-box\" process, providing limited transparency and interpretability. Therefore, this study developed an integrated experimental PTT system and numerical inversion framework. Firstly, a novel multi-point PTT system equipped with three axially distributed pressure sensors was developed to directly monitor the internal pore pressure evolution. The hydraulic/chemical loading procedure was designed to measure the pressure transmission behavior of anisotropic Longmaxi shale. Next, an anisotropic hydraulic-chemical coupling model was developed based on extended chemo-poroelastic theory, and a grid search-based inversion framework was further implemented to estimate the hydro-chemical coupling parameters of anisotropic shale. Then, the multi-point pressure response was examined for anisotropic Longmaxi shale, and the anisotropic permeability, solute diffusion, and reflection coefficients were inverted. Finally, the merits of multi-point PTT compared to single-point PTT were thoroughly examined. Furthermore, the conventional PTT results of the Pierre II and Ghom shales were benchmarked, and the implications for wellbore stability were thoroughly discussed. The results indicated that the Longmaxi shale exhibited significant anisotropy, with anisotropic ratios of 6.12, 8.33, and 1.38 for the permeability, diffusion, and reflection coefficients, respectively. The maximum and average relative errors of the inversion results based on the multi-point PTT results are 12.1 % and 2.56 %, respectively, which are 5.1 % and 0.71 % lower than those of traditional single-point PTT method. The grid search-based inversion framework was further validated by published datasets of both the Pierre II and the Ghom shales. This work demonstrated the efficacy of multi-point PTT system and transparent inversion framework for characterizing hydro-chemical coupling behavior of anisotropic shale and offering valuable implications for shale wellbore stability.</div></div>","PeriodicalId":54941,"journal":{"name":"International Journal of Rock Mechanics and Mining Sciences","volume":"197 ","pages":"Article 106351"},"PeriodicalIF":7.5,"publicationDate":"2025-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145567447","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 : 2025-11-17DOI: 10.1016/j.ijrmms.2025.106340
Yuantao Wen , Fanzhen Meng , Zhufeng Yue , Wei Wang , Pengyuan Liu , Zhengyang Xu , Dongliang Tian
An in-depth understanding of the mechanical behavior and failure characteristics of deep shale reservoirs under high temperatures and substantial tectonic stress is of great significance for the effective control of wellbore stability and optimized design of shale gas exploitation strategies. In this study, high-temperature true triaxial compression tests were conducted on Longmaxi Formation shale with four bedding angles (i.e., α = 0°, 30°, 60°, and 90°) at different temperatures (i.e., T = 298.15 K, 373.15 K, 423.15 K, and 473.15 K). The strength, deformation, and failure characteristics were studied, and the relationship between peak strain and temperature (or bedding angle) was quantitatively analyzed. The results show that peak strength decreases first and then increases with temperature, while residual strength increases monotonously. The strength and deformation anisotropies are strengthened within a specific temperature range. There is a critical temperature, over which the inherent anisotropy of shale is weakened. The macroscopic failure mode and the fracture surface morphology are affected by bedding orientation, and temperature mainly affects the post-failure fracture angle. Peak strain shows coupled dependence on temperature and bedding orientation, which can be approximately expressed by a quadratic function with hyperbolic coupling term. Additionally, elevated temperature leads to the unstable sliding on new fracture surface in residual stage. These findings provide valuable insights into the anisotropic mechanical behavior of deep reservoir shale and offer guidance for optimizing hydraulic fracturing stimulation schemes.
{"title":"Effects of bedding angle and temperature on mechanical properties and macro-micro failure characteristics of Longmaxi Formation shale under true triaxial compression","authors":"Yuantao Wen , Fanzhen Meng , Zhufeng Yue , Wei Wang , Pengyuan Liu , Zhengyang Xu , Dongliang Tian","doi":"10.1016/j.ijrmms.2025.106340","DOIUrl":"10.1016/j.ijrmms.2025.106340","url":null,"abstract":"<div><div>An in-depth understanding of the mechanical behavior and failure characteristics of deep shale reservoirs under high temperatures and substantial tectonic stress is of great significance for the effective control of wellbore stability and optimized design of shale gas exploitation strategies. In this study, high-temperature true triaxial compression tests were conducted on Longmaxi Formation shale with four bedding angles (i.e., <em>α</em> = 0°, 30°, 60°, and 90°) at different temperatures (i.e., <em>T</em> = 298.15 K, 373.15 K, 423.15 K, and 473.15 K). The strength, deformation, and failure characteristics were studied, and the relationship between peak strain and temperature (or bedding angle) was quantitatively analyzed. The results show that peak strength decreases first and then increases with temperature, while residual strength increases monotonously. The strength and deformation anisotropies are strengthened within a specific temperature range. There is a critical temperature, over which the inherent anisotropy of shale is weakened. The macroscopic failure mode and the fracture surface morphology are affected by bedding orientation, and temperature mainly affects the post-failure fracture angle. Peak strain shows coupled dependence on temperature and bedding orientation, which can be approximately expressed by a quadratic function with hyperbolic coupling term. Additionally, elevated temperature leads to the unstable sliding on new fracture surface in residual stage. These findings provide valuable insights into the anisotropic mechanical behavior of deep reservoir shale and offer guidance for optimizing hydraulic fracturing stimulation schemes.</div></div>","PeriodicalId":54941,"journal":{"name":"International Journal of Rock Mechanics and Mining Sciences","volume":"197 ","pages":"Article 106340"},"PeriodicalIF":7.5,"publicationDate":"2025-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145553997","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 : 2025-11-16DOI: 10.1016/j.ijrmms.2025.106343
Liangjie Gu , Guo-Qiang Zhu , Shaojun Li , Shuo Yu , Yangyi Zhou , Yan Zhang
During the excavation of deep hard rock engineering, the strain energy of the surrounding rock mass exhibits significant spatiotemporal heterogeneity due to complex true triaxial unloading paths. This poses substantial challenges for predicting dynamic disasters such as rockbursts. Conventional studies are mostly limited to single stress path assumptions, making it difficult to reveal the energy differentiation mechanisms under different true triaxial unloading paths in deep excavation. This study designed cyclic loading tests under five typical true triaxial unloading paths for deep excavation based on a true triaxial testing system. By analyzing the stress-strain hysteresis curves during cyclic loading, a calculation method for rock strain energy under different true triaxial unloading paths with cyclic loading was proposed, and the differential distribution laws of strain energy in hard rock under different true triaxial unloading paths were revealed. The results demonstrate that true triaxial unloading paths with increasing maximum or intermediate principal stress can enhance the total strain energy and elastic energy of rock, while unloading the minimum principal stress induces tensile failure, leading to a surge in dissipative energy. The essence lies in the fact that the three-dimensional stress adjustment dominates the energy accumulation and dissipation process. Additionally, the difference in dissipative energy loss between the intermediate and minimum principal stress directions is positively correlated with the macro-failure angle of the rock, and the greater difference in dissipative energy loss coefficients correspond to more pronounced tensile failure characteristics and larger failure angles. A rockburst tendency index quantifies the regulatory effect of the intermediate principal stress on rockburst, revealing the catastrophe mechanism dominated by elastic energy storage under true triaxial constraints. The research results provide a theoretical basis for the stability evaluation and disaster warning of surrounding rocks in deep engineering.
{"title":"Strain energy calculation and differential evolution in deep hard rocks under different true triaxial unloading paths with cyclic loading","authors":"Liangjie Gu , Guo-Qiang Zhu , Shaojun Li , Shuo Yu , Yangyi Zhou , Yan Zhang","doi":"10.1016/j.ijrmms.2025.106343","DOIUrl":"10.1016/j.ijrmms.2025.106343","url":null,"abstract":"<div><div>During the excavation of deep hard rock engineering, the strain energy of the surrounding rock mass exhibits significant spatiotemporal heterogeneity due to complex true triaxial unloading paths. This poses substantial challenges for predicting dynamic disasters such as rockbursts. Conventional studies are mostly limited to single stress path assumptions, making it difficult to reveal the energy differentiation mechanisms under different true triaxial unloading paths in deep excavation. This study designed cyclic loading tests under five typical true triaxial unloading paths for deep excavation based on a true triaxial testing system. By analyzing the stress-strain hysteresis curves during cyclic loading, a calculation method for rock strain energy under different true triaxial unloading paths with cyclic loading was proposed, and the differential distribution laws of strain energy in hard rock under different true triaxial unloading paths were revealed. The results demonstrate that true triaxial unloading paths with increasing maximum or intermediate principal stress can enhance the total strain energy and elastic energy of rock, while unloading the minimum principal stress induces tensile failure, leading to a surge in dissipative energy. The essence lies in the fact that the three-dimensional stress adjustment dominates the energy accumulation and dissipation process. Additionally, the difference in dissipative energy loss between the intermediate and minimum principal stress directions is positively correlated with the macro-failure angle of the rock, and the greater difference in dissipative energy loss coefficients correspond to more pronounced tensile failure characteristics and larger failure angles. A rockburst tendency index quantifies the regulatory effect of the intermediate principal stress on rockburst, revealing the catastrophe mechanism dominated by elastic energy storage under true triaxial constraints. The research results provide a theoretical basis for the stability evaluation and disaster warning of surrounding rocks in deep engineering.</div></div>","PeriodicalId":54941,"journal":{"name":"International Journal of Rock Mechanics and Mining Sciences","volume":"197 ","pages":"Article 106343"},"PeriodicalIF":7.5,"publicationDate":"2025-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145531395","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 : 2025-11-14DOI: 10.1016/j.ijrmms.2025.106341
Yuxuan Peng , Liyuan Yu , Jiayu Qian , Minghe Ju , Shentao Geng , Wei Li , Jingwei Liu
<div><div>The dynamic damage mechanisms of granite with different grain sizes under multi-velocity and multi-angle penetration are crucial for optimizing the design of underground protective structures and evaluating the impact resistance of rock masses. Although previous studies have focused on the penetration mechanisms of rocks under individual variables, such as penetration velocity, biting angle, and grain size, they often overlook the coupled effects of these factors on crack propagation behavior and failure patterns during penetration. In this study, hypervelocity penetration tests were conducted on granite with a two-stage light gas gun (50/20 mm caliber) under four different impact pressures (14, 15, 16, and 17 MPa) and at four different biting angles (0°, 15°, 30°, and 45°). To quantify the resulting crater morphology parameters—such as the equivalent diameter, penetration depth, crater area, and crater volume—3D scanning and MATLAB point cloud processing techniques were combined with both quantitative and qualitative analyses of fragment splashing during penetration. The evolution of the crater parameters for two granite types (coarse-grained and fine-grained) at various penetration velocities and angles was analyzed in detail. A theoretical model for predicting penetration depth, which incorporates the coupled effects of grain size, penetration velocity, and biting angle, was proposed. The results indicate that fragment splashing velocities result in an axisymmetric distribution under normal penetration conditions. As the biting angle increases, high-speed fragments are shifted toward the impact-opposite side, whereas higher penetration velocities reduce the total number of splashed fragments. In coarse-grained granite, the crater parameters increase with increasing penetration velocity but decrease with increasing biting angle, primarily because of weak grain boundaries and multi-scale crack branching. The fine-grained granite exhibits a similar trend, with the crater parameters increasing with increasing velocity but the penetration depth decreasing with increasing biting angle. However, at high penetration velocities and intermediate biting angles (e.g., 30°), the synergistic propagation of transgranular cracks results in a non-monotonic trend for the crater area and volume: they initially increase, but then decrease as the biting angle rises. At lower velocities, insufficient energy limits short-range crack propagation, resulting in monotonic decreases in the crater area and volume with increasing biting angle. The increasing rates of the crater parameters in coarse-grained granite decrease monotonically with increasing biting angle within a certain velocity range. In contrast, those in fine-grained granite first increase but then decrease because of the synergistic effects of normal-tangential stresses at higher biting angles. Compared with fine-grained granite, coarse-grained granite has a higher strain rate sensitivity coeffici
{"title":"Multi-angle and velocity response of granite with different grain sizes to the penetration performance of rigid tungsten alloy projectiles","authors":"Yuxuan Peng , Liyuan Yu , Jiayu Qian , Minghe Ju , Shentao Geng , Wei Li , Jingwei Liu","doi":"10.1016/j.ijrmms.2025.106341","DOIUrl":"10.1016/j.ijrmms.2025.106341","url":null,"abstract":"<div><div>The dynamic damage mechanisms of granite with different grain sizes under multi-velocity and multi-angle penetration are crucial for optimizing the design of underground protective structures and evaluating the impact resistance of rock masses. Although previous studies have focused on the penetration mechanisms of rocks under individual variables, such as penetration velocity, biting angle, and grain size, they often overlook the coupled effects of these factors on crack propagation behavior and failure patterns during penetration. In this study, hypervelocity penetration tests were conducted on granite with a two-stage light gas gun (50/20 mm caliber) under four different impact pressures (14, 15, 16, and 17 MPa) and at four different biting angles (0°, 15°, 30°, and 45°). To quantify the resulting crater morphology parameters—such as the equivalent diameter, penetration depth, crater area, and crater volume—3D scanning and MATLAB point cloud processing techniques were combined with both quantitative and qualitative analyses of fragment splashing during penetration. The evolution of the crater parameters for two granite types (coarse-grained and fine-grained) at various penetration velocities and angles was analyzed in detail. A theoretical model for predicting penetration depth, which incorporates the coupled effects of grain size, penetration velocity, and biting angle, was proposed. The results indicate that fragment splashing velocities result in an axisymmetric distribution under normal penetration conditions. As the biting angle increases, high-speed fragments are shifted toward the impact-opposite side, whereas higher penetration velocities reduce the total number of splashed fragments. In coarse-grained granite, the crater parameters increase with increasing penetration velocity but decrease with increasing biting angle, primarily because of weak grain boundaries and multi-scale crack branching. The fine-grained granite exhibits a similar trend, with the crater parameters increasing with increasing velocity but the penetration depth decreasing with increasing biting angle. However, at high penetration velocities and intermediate biting angles (e.g., 30°), the synergistic propagation of transgranular cracks results in a non-monotonic trend for the crater area and volume: they initially increase, but then decrease as the biting angle rises. At lower velocities, insufficient energy limits short-range crack propagation, resulting in monotonic decreases in the crater area and volume with increasing biting angle. The increasing rates of the crater parameters in coarse-grained granite decrease monotonically with increasing biting angle within a certain velocity range. In contrast, those in fine-grained granite first increase but then decrease because of the synergistic effects of normal-tangential stresses at higher biting angles. Compared with fine-grained granite, coarse-grained granite has a higher strain rate sensitivity coeffici","PeriodicalId":54941,"journal":{"name":"International Journal of Rock Mechanics and Mining Sciences","volume":"197 ","pages":"Article 106341"},"PeriodicalIF":7.5,"publicationDate":"2025-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145521284","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 : 2025-11-14DOI: 10.1016/j.ijrmms.2025.106302
Javiera Brevis , Fernanda Vera , René Gómez , Ebrahim F. Salmi
The continuous decline in ore grades has driven the mining industry to adopt innovative strategies to sustain and potentially increase production, particularly in response to the rising demand for strategic and critical minerals such as copper, which is essential for the energy transition. In underground mining, such as sublevel caving operations, ore passes are commonly used to transport ore between levels. Expanding and optimising the use of ore passes can improve operational efficiency, reduce energy consumption, and lower carbon emissions associated with hauling.
However, significant challenges arise in maintaining reliable gravitational flow within ore passes due to substantial vertical distances and increasing mining depths. To address these challenges, this study utilises a scaled physical model to investigate the flow behaviour of various particle types within an ore pass. The analysis considers multiple variables, including filling levels, particle size distributions, and particle properties. A total of 4160 flow experiments were conducted across 52 combinations of particle shapes and sizes to quantify the influence of these variables on material flow.
The highest number of hang-ups was observed for large triangular prismatic particles, with 125 events, followed by large spherical particles, which exhibited 96 hang-ups. In contrast, no hang-ups occurred for small spherical or octahedral particles. The hang-up frequency index decreased by 98.48 % when sphericity was reduced by 23.47 %, indicating a strong influence of particle shape on flow behaviour. For spherical particles, lower ore pass filling levels reduced the occurrence of hang-ups, whereas this effect was not observed in mixed prismatic particle shapes. This detailed analysis of hang-up events under varying conditions can help to identify critical scenarios affecting particle flow within ore passes. The findings provide essential insights into the parameters governing particle movement, thereby advancing the understanding of complex flow dynamics in ore pass operations.
{"title":"Physical modelling of ore flow in ore passes for haulage decarbonisation in deep mining","authors":"Javiera Brevis , Fernanda Vera , René Gómez , Ebrahim F. Salmi","doi":"10.1016/j.ijrmms.2025.106302","DOIUrl":"10.1016/j.ijrmms.2025.106302","url":null,"abstract":"<div><div>The continuous decline in ore grades has driven the mining industry to adopt innovative strategies to sustain and potentially increase production, particularly in response to the rising demand for strategic and critical minerals such as copper, which is essential for the energy transition. In underground mining, such as sublevel caving operations, ore passes are commonly used to transport ore between levels. Expanding and optimising the use of ore passes can improve operational efficiency, reduce energy consumption, and lower carbon emissions associated with hauling.</div><div>However, significant challenges arise in maintaining reliable gravitational flow within ore passes due to substantial vertical distances and increasing mining depths. To address these challenges, this study utilises a scaled physical model to investigate the flow behaviour of various particle types within an ore pass. The analysis considers multiple variables, including filling levels, particle size distributions, and particle properties. A total of 4160 flow experiments were conducted across 52 combinations of particle shapes and sizes to quantify the influence of these variables on material flow.</div><div>The highest number of hang-ups was observed for large triangular prismatic particles, with 125 events, followed by large spherical particles, which exhibited 96 hang-ups. In contrast, no hang-ups occurred for small spherical or octahedral particles. The hang-up frequency index decreased by 98.48 % when sphericity was reduced by 23.47 %, indicating a strong influence of particle shape on flow behaviour. For spherical particles, lower ore pass filling levels reduced the occurrence of hang-ups, whereas this effect was not observed in mixed prismatic particle shapes. This detailed analysis of hang-up events under varying conditions can help to identify critical scenarios affecting particle flow within ore passes. The findings provide essential insights into the parameters governing particle movement, thereby advancing the understanding of complex flow dynamics in ore pass operations.</div></div>","PeriodicalId":54941,"journal":{"name":"International Journal of Rock Mechanics and Mining Sciences","volume":"197 ","pages":"Article 106302"},"PeriodicalIF":7.5,"publicationDate":"2025-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145521283","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 : 2025-11-12DOI: 10.1016/j.ijrmms.2025.106329
Jia Wang , Wen Zhang , Han Yin , Rui Fu , Qi Sun , Jiali Han , Junqi Chen
Large jointed rock masses are characterized by numerous discontinuities across multiple scales. Oversimplifying these features leads to inaccurate mechanical representation, while fully resolving them in numerical models is computationally prohibitive. This study proposes a multi-scale structural equivalent method that integrates explicit modelling of large- and medium-scale discontinuities, while representing small-scale discontinuities through equivalent continuum parameters. The method is developed based on 3D discrete fracture network (DFN) modelling and the representative elementary volume (REV) concept. A high-steep rock slope located in the Tibet Autonomous Region, China, serves as the application site. Multi-scale discontinuity data were rapidly extracted using unmanned aerial vehicle (UAV) photogrammetry combined with automated interpretation. The further generated 3D DFN model contains millions of discontinuities, so the synthetic rock mass (SRM) technique in 3DEC was employed to equivalently embed small-scale discontinuities into intact rock. To determine the input parameters of the SRM model, numerical uniaxial and triaxial compression experiments were performed. Results confirm that small-scale discontinuities significantly weaken rock mass strength, indicating that their degradation effect should be included in slope stability analysis. The established multi-scale slope model effectively captures overall deformation zones and primary failure boundaries controlled by large-scale discontinuities, as well as localized collapses associated with medium-scale discontinuities. Field observations further validate the accuracy of this approach, demonstrating its potential for application in large jointed rock mass projects.
{"title":"A novel multi-scale structural equivalent method for jointed rock masses and its application to slope stability analysis","authors":"Jia Wang , Wen Zhang , Han Yin , Rui Fu , Qi Sun , Jiali Han , Junqi Chen","doi":"10.1016/j.ijrmms.2025.106329","DOIUrl":"10.1016/j.ijrmms.2025.106329","url":null,"abstract":"<div><div>Large jointed rock masses are characterized by numerous discontinuities across multiple scales. Oversimplifying these features leads to inaccurate mechanical representation, while fully resolving them in numerical models is computationally prohibitive. This study proposes a multi-scale structural equivalent method that integrates explicit modelling of large- and medium-scale discontinuities, while representing small-scale discontinuities through equivalent continuum parameters. The method is developed based on 3D discrete fracture network (DFN) modelling and the representative elementary volume (REV) concept. A high-steep rock slope located in the Tibet Autonomous Region, China, serves as the application site. Multi-scale discontinuity data were rapidly extracted using unmanned aerial vehicle (UAV) photogrammetry combined with automated interpretation. The further generated 3D DFN model contains millions of discontinuities, so the synthetic rock mass (SRM) technique in 3DEC was employed to equivalently embed small-scale discontinuities into intact rock. To determine the input parameters of the SRM model, numerical uniaxial and triaxial compression experiments were performed. Results confirm that small-scale discontinuities significantly weaken rock mass strength, indicating that their degradation effect should be included in slope stability analysis. The established multi-scale slope model effectively captures overall deformation zones and primary failure boundaries controlled by large-scale discontinuities, as well as localized collapses associated with medium-scale discontinuities. Field observations further validate the accuracy of this approach, demonstrating its potential for application in large jointed rock mass projects.</div></div>","PeriodicalId":54941,"journal":{"name":"International Journal of Rock Mechanics and Mining Sciences","volume":"197 ","pages":"Article 106329"},"PeriodicalIF":7.5,"publicationDate":"2025-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145515805","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 : 2025-11-12DOI: 10.1016/j.ijrmms.2025.106339
Ning Yang , Peng-Zhi Pan , Shuting Miao , Wenbo Hou
Under deep injection disturbance, critical state faults in the quiescent period are prone to reactivation, and the induced stick-slip behavior may trigger seismic hazards. The healing mechanism of quiescent faults exerts significant control on the reactivation stability; however, current research on fault healing still relies on ex-post result analysis after reactivation. To address this limitation, we designed and conducted shear-flow experiments with variables of stress environments and healing periods, based on a fault slip model inclined to the loading direction. The results show that the absolute stress-strain ratio () in the stable micro-slip stage decreases from an initial 10 GPa to 0 with increasing healing period, while the product of healing period and holding-phase shear stress (TIEC) reduces from an initial 300 MPa·s to 225 MPa·s. This indicates that the higher the stress environment and the longer the healing period, the earlier the fault tends to become unstable. Statistical analysis reveals that when shear stress is below 60 MPa, the positive correlation coefficient between cumulative slip distance during the healing period and reactivation intensity is mostly above 0.75, whereas excessively high stress weakens this correlation. Microscopic observation of slip traces shows that continuous micro-slip does not prevent healing, which may be attributed to the plowing of asperities. These results facilitate exploring and quantifying the correlation between fault healing and reactivation stability, and support interpreting and predicting fault reactivation risks at an earlier stage.
{"title":"Laboratory-scale characteristics of micro-slip during fault quiescence and implications for injection-induced reactivation stability","authors":"Ning Yang , Peng-Zhi Pan , Shuting Miao , Wenbo Hou","doi":"10.1016/j.ijrmms.2025.106339","DOIUrl":"10.1016/j.ijrmms.2025.106339","url":null,"abstract":"<div><div>Under deep injection disturbance, critical state faults in the quiescent period are prone to reactivation, and the induced stick-slip behavior may trigger seismic hazards. The healing mechanism of quiescent faults exerts significant control on the reactivation stability; however, current research on fault healing still relies on ex-post result analysis after reactivation. To address this limitation, we designed and conducted shear-flow experiments with variables of stress environments and healing periods, based on a fault slip model inclined to the loading direction. The results show that the absolute stress-strain ratio (<span><math><mrow><mi>γ</mi></mrow></math></span>) in the stable micro-slip stage decreases from an initial 10 GPa to 0 with increasing healing period, while the product of healing period and holding-phase shear stress (<em>TIEC</em>) reduces from an initial 300 MPa·s to 225 MPa·s. This indicates that the higher the stress environment and the longer the healing period, the earlier the fault tends to become unstable. Statistical analysis reveals that when shear stress is below 60 MPa, the positive correlation coefficient between cumulative slip distance during the healing period and reactivation intensity is mostly above 0.75, whereas excessively high stress weakens this correlation. Microscopic observation of slip traces shows that continuous micro-slip does not prevent healing, which may be attributed to the plowing of asperities. These results facilitate exploring and quantifying the correlation between fault healing and reactivation stability, and support interpreting and predicting fault reactivation risks at an earlier stage.</div></div>","PeriodicalId":54941,"journal":{"name":"International Journal of Rock Mechanics and Mining Sciences","volume":"197 ","pages":"Article 106339"},"PeriodicalIF":7.5,"publicationDate":"2025-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145515662","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 : 2025-11-10DOI: 10.1016/j.ijrmms.2025.106326
Carlos Guevara Morel, Jan Thiedau, Jobst Maßmann
A crystalline host rock for the deep geological disposal of heat generating nuclear waste is one of the options discussed in Germany. Since a sufficiently large undisturbed rock zone to provide the essential safety function for containment of the waste cannot be assumed, a concept for disposal in multiple smaller unfractured rock zones has been developed and investigated in the joint research project CHRISTA-II. Regulation then requires the proof of integrity under thermo-hydro-mechanical (THM) load introduced by the repository. This contribution presents a modeling approach for the THM system evolution that allows for the assessment of the safety function of the geological barrier in crystalline rock, considering German regulatory requirements. Moreover with the proposed modeling approach, the quantification of the potential safety reserves at the repository can be quantified. Modeling results show that for the selected model conditions, the repository units have less safety reserves regarding tensile failure as compared to dilatant or thermal induced failure.
{"title":"Numerical assessment of the barrier integrity for a generic nuclear waste repository in crystalline rock","authors":"Carlos Guevara Morel, Jan Thiedau, Jobst Maßmann","doi":"10.1016/j.ijrmms.2025.106326","DOIUrl":"10.1016/j.ijrmms.2025.106326","url":null,"abstract":"<div><div>A crystalline host rock for the deep geological disposal of heat generating nuclear waste is one of the options discussed in Germany. Since a sufficiently large undisturbed rock zone to provide the essential safety function for containment of the waste cannot be assumed, a concept for disposal in multiple smaller unfractured rock zones has been developed and investigated in the joint research project CHRISTA-II. Regulation then requires the proof of integrity under thermo-hydro-mechanical (THM) load introduced by the repository. This contribution presents a modeling approach for the THM system evolution that allows for the assessment of the safety function of the geological barrier in crystalline rock, considering German regulatory requirements. Moreover with the proposed modeling approach, the quantification of the potential safety reserves at the repository can be quantified. Modeling results show that for the selected model conditions, the repository units have less safety reserves regarding tensile failure as compared to dilatant or thermal induced failure.</div></div>","PeriodicalId":54941,"journal":{"name":"International Journal of Rock Mechanics and Mining Sciences","volume":"197 ","pages":"Article 106326"},"PeriodicalIF":7.5,"publicationDate":"2025-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145485533","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 : 2025-11-10DOI: 10.1016/j.ijrmms.2025.106327
Zhenting Sun , Lei Ma , Quan Li , Yaping Deng , Han Qiu , Haichun Ma , Cihai Chen , Yongshuai Yan , Jiazhong Qian
Characterizing fracture networks is critical for groundwater development, geothermal exploitation, hydrocarbon recovery, and geological CO2 sequestration, yet their complex and uncertain spatial distribution poses a persistent challenge. This study proposes an intelligent inversion framework that integrates a 3D-UNet surrogate model, reversible jump Markov Chain Monte Carlo (rjMCMC), and multi-source data fusion for three-dimensional discrete fracture network (DFN) characterization at the field scale. Within this framework, a 3D-UNet model trained on large datasets of fracture configurations, hydraulic head, and electrical potential provides an efficient initial inversion of fracture parameters. Fracture geometries are then extracted with the RANSAC algorithm and iteratively refined via rjMCMC, where the surrogate 3D-UNet replaces conventional forward modeling. This innovation reduces computational costs by an order of magnitude, enabling efficient large-scale inversion. Furthermore, the fusion of electrical potential with hydraulic head data enhances inversion accuracy by about 10 %. Validation demonstrates that the framework reliably reconstructs the spatial distribution of fracture networks, capturing both low-density zones and dominant hydraulic pathways in highly heterogeneous domains. By combining computational efficiency with improved accuracy, this approach offers a practical and scalable solution for field-scale fracture network characterization in a wide range of hydrogeological and engineering applications.
{"title":"Three-dimensional discrete fracture network identification based on deep learning and reversible jump Markov chain Monte Carlo algorithm","authors":"Zhenting Sun , Lei Ma , Quan Li , Yaping Deng , Han Qiu , Haichun Ma , Cihai Chen , Yongshuai Yan , Jiazhong Qian","doi":"10.1016/j.ijrmms.2025.106327","DOIUrl":"10.1016/j.ijrmms.2025.106327","url":null,"abstract":"<div><div>Characterizing fracture networks is critical for groundwater development, geothermal exploitation, hydrocarbon recovery, and geological CO<sub>2</sub> sequestration, yet their complex and uncertain spatial distribution poses a persistent challenge. This study proposes an intelligent inversion framework that integrates a 3D-UNet surrogate model, reversible jump Markov Chain Monte Carlo (rjMCMC), and multi-source data fusion for three-dimensional discrete fracture network (DFN) characterization at the field scale. Within this framework, a 3D-UNet model trained on large datasets of fracture configurations, hydraulic head, and electrical potential provides an efficient initial inversion of fracture parameters. Fracture geometries are then extracted with the RANSAC algorithm and iteratively refined via rjMCMC, where the surrogate 3D-UNet replaces conventional forward modeling. This innovation reduces computational costs by an order of magnitude, enabling efficient large-scale inversion. Furthermore, the fusion of electrical potential with hydraulic head data enhances inversion accuracy by about 10 %. Validation demonstrates that the framework reliably reconstructs the spatial distribution of fracture networks, capturing both low-density zones and dominant hydraulic pathways in highly heterogeneous domains. By combining computational efficiency with improved accuracy, this approach offers a practical and scalable solution for field-scale fracture network characterization in a wide range of hydrogeological and engineering applications.</div></div>","PeriodicalId":54941,"journal":{"name":"International Journal of Rock Mechanics and Mining Sciences","volume":"197 ","pages":"Article 106327"},"PeriodicalIF":7.5,"publicationDate":"2025-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145476166","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 : 2025-11-09DOI: 10.1016/j.ijrmms.2025.106338
Kai Guan , Runze Zhu , Ignacio Pérez-Rey , Wancheng Zhu , Xige Liu , Jianyu Zhou
Rock creep and dynamic behaviors are distinct mechanical responses with different strain rates, and their interaction can cause asynchronous deformation in anchoring systems, reducing bolt prestress and increasing time-dependent instability risk. Using the self-developed rock creep-impact testing machine, this study highlights that under combined creep and dynamic loading, unbolted specimens tend to experience delayed failure, whereas bolt-reinforced specimens fail more promptly during impact, indicating improved predictability and stability due to reinforcement. The application of bolt prestress significantly enhances impact resistance by suppressing axial strain increases and damage during dynamic events, thereby extending the time-to-failure and improving overall performance. During creep, bolt strain gradually increases, but impact causes rapid escalation, demonstrating that transient disturbances are more effective in activating bolt reinforcement than slow creep. Repeated dynamic impacts diminish anchoring effectiveness, increasing acoustic emission energy, but higher prestress levels delay weakening and facilitate a transition to more controlled energy dissipation. Prestress initially decline rapidly before stabilizing, with subsequent impacts inducing stepwise reductions and occasional abnormal rebounds that may serve as early-warning signals for potential failure. Prestress relaxation arises from bolt elongation pre-impact and time-dependent damage to the rock mass post-impact, necessitating timely re-tensioning in vibration-prone environments. The progression and failure of cracks are significantly influenced by prestress levels, with higher prestress shifting through-cracking extending along the joint towards both the top and bottom to propagating laterally across the specimen, especially near the tray region, thereby reducing localized damage. Overall, the findings underscore the critical role of prestress management and reinforcement strategies in improving the resilience of anchoring systems under creep stress and dynamic impact conditions, contributing to safer and more durable rock engineering applications.
{"title":"Creep behavior and prestress relaxation mechanism of bolt-reinforced jointed specimen disturbed by dynamic impact","authors":"Kai Guan , Runze Zhu , Ignacio Pérez-Rey , Wancheng Zhu , Xige Liu , Jianyu Zhou","doi":"10.1016/j.ijrmms.2025.106338","DOIUrl":"10.1016/j.ijrmms.2025.106338","url":null,"abstract":"<div><div>Rock creep and dynamic behaviors are distinct mechanical responses with different strain rates, and their interaction can cause asynchronous deformation in anchoring systems, reducing bolt prestress and increasing time-dependent instability risk. Using the self-developed rock creep-impact testing machine, this study highlights that under combined creep and dynamic loading, unbolted specimens tend to experience delayed failure, whereas bolt-reinforced specimens fail more promptly during impact, indicating improved predictability and stability due to reinforcement. The application of bolt prestress significantly enhances impact resistance by suppressing axial strain increases and damage during dynamic events, thereby extending the time-to-failure and improving overall performance. During creep, bolt strain gradually increases, but impact causes rapid escalation, demonstrating that transient disturbances are more effective in activating bolt reinforcement than slow creep. Repeated dynamic impacts diminish anchoring effectiveness, increasing acoustic emission energy, but higher prestress levels delay weakening and facilitate a transition to more controlled energy dissipation. Prestress initially decline rapidly before stabilizing, with subsequent impacts inducing stepwise reductions and occasional abnormal rebounds that may serve as early-warning signals for potential failure. Prestress relaxation arises from bolt elongation pre-impact and time-dependent damage to the rock mass post-impact, necessitating timely re-tensioning in vibration-prone environments. The progression and failure of cracks are significantly influenced by prestress levels, with higher prestress shifting through-cracking extending along the joint towards both the top and bottom to propagating laterally across the specimen, especially near the tray region, thereby reducing localized damage. Overall, the findings underscore the critical role of prestress management and reinforcement strategies in improving the resilience of anchoring systems under creep stress and dynamic impact conditions, contributing to safer and more durable rock engineering applications.</div></div>","PeriodicalId":54941,"journal":{"name":"International Journal of Rock Mechanics and Mining Sciences","volume":"196 ","pages":"Article 106338"},"PeriodicalIF":7.5,"publicationDate":"2025-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145473193","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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