International Journal of Rock Mechanics and Mining Sciences最新文献

{"title":"An experimental investigation on the dynamic shear characteristics of wet joints","authors":"Shijie Xie ,&nbsp;Jianchun Li ,&nbsp;Shanyong Wang ,&nbsp;Xing Li","doi":"10.1016/j.ijrmms.2025.106193","DOIUrl":"10.1016/j.ijrmms.2025.106193","url":null,"abstract":"<div><div>This study investigated the dynamic shear behavior of planar granite joints under dry and wet conditions using the impact-induced direct shear test. The effects of shear rate and normal stress on the dynamic shear properties were examined on dry and wet joints under four different normal stress conditions. Dynamic shear stress and shear displacement were measured by stress wave acquisition and digital image correlation method, respectively. Dynamic friction coefficients were calculated using the Mohr-Coulomb criterion. Additionally, fracture energy was calculated and compared with nano-indentation tests. The results revealed that moisture significantly alters the dynamic shear response of rock joints. Although both dry and wet joints exhibited dynamic shear stress–displacement curves consisting of two stages, namely a shear stress accumulation stage and a slip stage, the wet joints displayed notably greater strength degradation. A linearly decreasing relationship between maximum shear displacement and normal stress was observed for both joint types. Within the shear displacement rate range of 4–6 m/s, both dry and wet joints exhibited a negative rate effect, wherein dynamic shear strength decreases with increasing shear rate. Wet joints showed a significant 53.2 % reduction in dynamic friction coefficient, compared to 33.9 % for dry joints. Nano-indentation tests further revealed differences in microscale mechanical behavior between dry and wet joints. Compared to dry joints, wet joints showed a 74.2 % increase in maximum indentation depth and a 50.69 % reduction in fracture energy. These findings suggest that wetting-induced strength weakening of rock joints was governed by reductions in fracture energy and frictional properties.</div></div>","PeriodicalId":54941,"journal":{"name":"International Journal of Rock Mechanics and Mining Sciences","volume":"194 ","pages":"Article 106193"},"PeriodicalIF":7.0,"publicationDate":"2025-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144686958","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}

{"title":"Quantifying the effects of laminae on mechanical and damage characteristic of shale: Numerical investigation on digital rock models","authors":"Dingdian Yan ,&nbsp;Luanxiao Zhao ,&nbsp;Minghui Lu ,&nbsp;Yonghao Zhang ,&nbsp;Min Chen ,&nbsp;Fengshou Zhang","doi":"10.1016/j.ijrmms.2025.106218","DOIUrl":"10.1016/j.ijrmms.2025.106218","url":null,"abstract":"<div><div>Sedimentary rocks with well-developed laminated structures, such as shales, exhibit intricate mechanical responses driven by the variability and heterogeneity of lamina attributes. Quantifying the influence of individual lamina attributes on rock mechanical responses is essential for understanding the complex deformation and failure mechanisms of laminated shales, with broad implications for geo-applications across Earth sciences and energy fields. However, precisely decoupling lamina-related variables in rock experiments is challenging. We develop a digital rock workflow that reconstructs internal fabric and lamina characteristics by integrating CT-derived shale microstructures with a discrete element method-based laminated particle model, with contact parameters for each lamina type calibrated using experimental data. Simulation results show that increasing soft laminae (clay) quantity reduces strength by 15 % and modulus by 35 %, while greater thickness lowers strength by 35 % and halves the modulus, both raising Poisson's ratio. Conversely, shales interspersed with stiff laminae (silica) exhibit the opposite variation. Variations in lamina properties significantly affect microcracking behavior during failure, complicating the damage mode. Increased lamina quantity and thickness amplify the complexity of microcrack evolution, with soft laminae playing a dominant role by facilitating shear slip and promoting shear failure. Analysis of internal stress characteristics within soft and stiff laminae, boundary regions, and the rock matrix reveals that these mechanical variations in laminated shale stem from stress mismatches across these structural components. The greater the disparity, the stronger the mechanical contrast, amplifying localized deformation and failure complexity. Our simulations align well with experimental data, highlighting the potential of digital shale modeling to quantitatively link rock mechanical properties with lamina attributes while providing a crucial micro-mechanical perspective.</div></div>","PeriodicalId":54941,"journal":{"name":"International Journal of Rock Mechanics and Mining Sciences","volume":"194 ","pages":"Article 106218"},"PeriodicalIF":7.0,"publicationDate":"2025-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144670369","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}

{"title":"A line-to-volume contact algorithm for modeling the complex bond-slip behavior of grouted bolts in rock mass","authors":"Huangcheng Fang ,&nbsp;Weijian Liang ,&nbsp;Zhen-Yu Yin ,&nbsp;Dingli Zhang ,&nbsp;Qian Fang","doi":"10.1016/j.ijrmms.2025.106215","DOIUrl":"10.1016/j.ijrmms.2025.106215","url":null,"abstract":"<div><div>Timely installation of rock bolts is essential in tunneling through weak surrounding rock to prevent rapid deformation behind the excavation face. However, understanding the support mechanism of rock bolts remains a challenge, primarily due to the highly nonlinear bond-slip behavior at the bolt-rock interface. This difficulty is further compounded by the large disparity in cross-sectional dimensions between the bolt and the surrounding rock mass. This study presents a novel and efficient finite element contact algorithm to simulate the interaction between rock bolts and the surrounding rock. Unlike conventional methods that establish direct contact constraints, our approach introduces relative displacement as the new degree of freedom (DOF) based on the dual Lagrange multiplier method. This new DOF is subsequently employed in the discretization of contact constraints and contact virtual work. The formulation enables direct integration of existing constitutive models for the bolt-rock interface, which are typically expressed in terms of relative slip displacement. In addition, it improves numerical stability by avoiding the saddle-point problems and spurious stress oscillations commonly observed in traditional contact formulations. Moreover, this method accommodates non-conforming meshes, enabling the rock bolt to be meshed separately and arbitrarily assembled into the mesh of the rock mass, thus enhancing the flexibility of numerical modeling. The accuracy and efficiency of our method are first validated against existing methods. Subsequently, the developed algorithm is applied to perform a detailed analysis of the mechanical response and support mechanism of rock bolts during tunnel excavation.</div></div>","PeriodicalId":54941,"journal":{"name":"International Journal of Rock Mechanics and Mining Sciences","volume":"194 ","pages":"Article 106215"},"PeriodicalIF":7.0,"publicationDate":"2025-07-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144662499","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}

{"title":"Investigation of physical mechanisms behind full-scale engineered barrier systems through coupled thermal-hydraulic-mechanical (THM) simulations","authors":"Chia-Wei Kuo ,&nbsp;Wan-Jung Kuo ,&nbsp;Chung-Yi Lin","doi":"10.1016/j.ijrmms.2025.106155","DOIUrl":"10.1016/j.ijrmms.2025.106155","url":null,"abstract":"<div><div>This work presents simulation results of the FEBEX experiment, performed using the 2019 rendition of the coupled thermal-hydraulic-mechanical-chemical simulator, HYDROGEOCHEM 5.3 (HGC 5.3 Taiwan Power Company version). These simulations were carried out as part of the DECOVALEX-2019 project. The simulations consider the variably saturated flow, thermal transport, and linear geomechanics, including the effects of bentonite swelling. This study systematically investigates the hydro-thermal-mechanical processes in bentonite, which services as the sealing material in a near-field full-scale engineering barrier system. It explores important issues such as how the engineering barrier in the disposal site undergoes resaturation processes, thermal transport processes, and the resulting stress behavior. The simulation results are compared with experiments to understand the underlying physical mechanisms. We can qualitatively and quantitatively predict most of the experimental results, including the evolution and radial distribution of relative humidity, the evolution of heating power, the evolution as well as axial and radial distribution of temperature, the evolution of total stress, and the distribution of degree of saturation and moisture content for the first and final dismantling.</div><div>Through this study, we aim to better understand the dominant physical mechanisms behind the evolution of material properties of engineering barriers. This understanding will enable us to evaluate the functions of near-field engineering barriers and improve the numerical technical capabilities for the safety assessment and analysis of nuclear waste disposal. The insights gained from this research can be applied to address important environmental issues involving these fundamental processes, particularly the safety of nuclear waste disposal repositories that use bentonite as a buffer or backfill material.</div></div>","PeriodicalId":54941,"journal":{"name":"International Journal of Rock Mechanics and Mining Sciences","volume":"194 ","pages":"Article 106155"},"PeriodicalIF":7.0,"publicationDate":"2025-07-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144633854","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}

{"title":"Comprehensive evaluation of three-dimensional Hoek–Brown strength criteria: Properties, applicability, and parameter reliability","authors":"Chenlong Su ,&nbsp;Hehua Zhu ,&nbsp;Wuqiang Cai ,&nbsp;Lianyang Zhang ,&nbsp;Haohua Chen ,&nbsp;Qi Zhang ,&nbsp;Zhi Zheng","doi":"10.1016/j.ijrmms.2025.106213","DOIUrl":"10.1016/j.ijrmms.2025.106213","url":null,"abstract":"<div><div>The Hoek–Brown (HB) criterion has evolved into a mature and widely adopted parameter system in rock mechanics. Although existing three-dimensional HB criteria consider the intermediate principal stress effect, issues concerning the reliability of their parameters and the inheritance of the HB parameter system remain insufficiently addressed. In this study, the failure strength distribution of sandstone on the π-plane is obtained through true triaxial failure test under the given stress conditions. The non-convexity of the rock strength on the π-plane is experimentally demonstrated for the first time, and its dual nonlinear tension-compression transition law on both the π-plane and the meridian plane is revealed. Based on 50 sets of true triaxial test data, a comparative analysis of 12 HB series criteria is conducted. The results indicate that the curvilinear hexagonal strength criterion is more consistent with the failure strength envelope morphology of sandstone and has a better comprehensive strength prediction accuracy of various rock types. Among criteria without introducing additional parameters, the generalized Zhang–Zhu criterion demonstrates the best comprehensive performance, maintaining the inheritance of the accumulated experience of the HB parameter system and facilitating practical engineering applications. While criteria incorporating additional parameters achieve higher prediction accuracy and parameter stability, their practical application is limited by ambiguous physical interpretations, immature parameter determination methods, and potential disruption of the original HB parameters, lacking guiding significance for rock mass engineering.</div></div>","PeriodicalId":54941,"journal":{"name":"International Journal of Rock Mechanics and Mining Sciences","volume":"194 ","pages":"Article 106213"},"PeriodicalIF":7.0,"publicationDate":"2025-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144623324","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}

{"title":"Integrating time of exposure into quantitative evolving rockfall hazard assessment for open-pit mining","authors":"F. Bahootoroody ,&nbsp;A. Giacomini ,&nbsp;K. Thoeni ,&nbsp;D.E. Guccione ,&nbsp;F. Ferrari ,&nbsp;M. Jaboyedoff","doi":"10.1016/j.ijrmms.2025.106216","DOIUrl":"10.1016/j.ijrmms.2025.106216","url":null,"abstract":"<div><div>A quantitative Evolving Rockfall Hazard Assessment (qERHA) methodology is proposed to address rockfall risks in open-pit mines, integrating site-specific factors such as failure frequency, block size distribution, and highwall geometry. Unlike conventional approaches reliant on return periods, qERHA introduces a novel time of exposure (ToE) framework tailored to mining operations, enabling hazard assessment over durations ranging from hourly shifts to multi-year plans. The implemented energy thresholds reflect mining infrastructure vulnerabilities. The methodology employs stochastic rockfall trajectory simulations, geological layer segmentation, and Poisson-derived likelihood analysis to generate spatially explicit hazard maps. These maps identify critical zones for targeted mitigation and operational planning based on safety considerations. A case study shows how qERHA can be applied to investigate the likelihood of rockfall occurrence in the context of machinery operating at the toe of a highwall over a period of 3 months. Results indicate that targeted reinforcement of critical geological layers significantly decreases the likelihood of rockfall hazards. The study bridges gaps in existing qualitative and quantitative hazard assessments by incorporating mining-specific energy thresholds and ToE metrics, offering a practical framework for enhancing safety and operational efficiency in open-pit environments.</div></div>","PeriodicalId":54941,"journal":{"name":"International Journal of Rock Mechanics and Mining Sciences","volume":"194 ","pages":"Article 106216"},"PeriodicalIF":7.0,"publicationDate":"2025-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144604641","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}

{"title":"Bayesian inversion of microseismic moment tensors with 3D velocity models and characteristic waveforms","authors":"Zhonghao Luo ,&nbsp;Xueyi Shang ,&nbsp;Yi Wang ,&nbsp;Jingnan Sun ,&nbsp;Yuanyuan Pu","doi":"10.1016/j.ijrmms.2025.106189","DOIUrl":"10.1016/j.ijrmms.2025.106189","url":null,"abstract":"<div><div>Microseismic (MS) source moment tensor (MT) plays an essential role in understanding dynamic disasters such as rock bursts in underground mines. However, the commonly used full-waveform MT inversion result can be affected by the adopted simple velocity model and MS waveform tails. To handle this, we proposed a source MT Bayesian inversion method through a three-dimensional (3D) velocity model and characteristic waveforms. Firstly, broadband Green's functions (10–70 Hz) were constructed using the spectral element method within a 3D velocity model, which realized a high-frequency up to 77Hz waveform modeling in a mining region for the first time. Then, a short-term average/long-term average (STA/LTA) technique was employed to pick seismic phase arrivals, enabling the extraction of characteristic waveform segments surrounding these arrivals. Finally, an MT Bayesian waveform inversion method was developed using the Markov Chain Monte Carlo (MCMC) technique. Three typical synthetic events and five blasting events were adopted to validate the proposed method. Synthetic results show that an average cross-correlation coefficient is more than 90 % when the signal-to-noise ratio (SNR) is larger than 10, representing a 5 % accuracy increase compared with that using a homogeneous velocity model. The MTs for the five blasting events achieved the average waveform fitting accuracy of 85.20 % and an isotropic (ISO) component of more than 50 %, showing satisfactory inversion results. Furthermore, two typical MS events were analyzed. The MS event 2 near the fault F350 shows a 26.43 % compensated linear vector dipole (CLVD) component with strike and dip angles aligning with the fault orientation. In contrast, the MS event 1 near fault F310 reveals a more complex focal mechanism affected by mining disturbances. It shows that mining disturbances can impact the CLVD component of MS events and offer valuable insights into mining-induced fault slips.</div></div>","PeriodicalId":54941,"journal":{"name":"International Journal of Rock Mechanics and Mining Sciences","volume":"194 ","pages":"Article 106189"},"PeriodicalIF":7.0,"publicationDate":"2025-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144604642","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}

{"title":"Representative elementary volume-enabled quality evaluation for complex structural rock masses: From the analytical perspective of the connectivity-controlled non-persistent fracture networks","authors":"Yongqiang Liu ,&nbsp;Jianping Chen ,&nbsp;Jiewei Zhan","doi":"10.1016/j.ijrmms.2025.106214","DOIUrl":"10.1016/j.ijrmms.2025.106214","url":null,"abstract":"<div><div>Rock mass quality evaluation is a critical preliminary step in rock engineering, yet conventional methods often overlook the analytical connectivity of non-persistent fracture networks, reducing their precision and scope. To bridge this gap, this study proposes a novel connectivity-based geological strength index (CGSI) for rock mass quality assessment and establishes explicit and quantitative conversion relationships between different classification systems, thereby improving reliability across diverse engineering contexts. Using the representative elementary volume (REV) as the fundamental scale, an extensive quality evaluation of homogeneous domain #7 on a high and steep slope was conducted. Samples were optimized based on the REV, and four established assessment systems were applied to formulate conversion expressions. By integrating their core principles, we developed CGSI and established twelve quantitative conversion relationships spanning different rock strength ranges. CGSI's novelty lies in its capacity to quantify rock mass quality at the REV scale by incorporating surface conditions, structural distribution, fracture connectivity and fracture orientation effects to capture the three-dimensional fracture network. Field investigations and comparative analyses validated CGSI, identifying grade III as the optimal quality for domain #7. Results demonstrate CGSI's superior conversion accuracy for fractured rock masses and its strong applicability in engineering practice. Extending the method to other homogeneous domains yielded overall quality ratings of II ∼ IV. Information entropy analysis revealed that the number of moderately dipping fracture sets, REV size and mean fracture size are the dominant controlling factors. Notably, domains #1, #4, #6, #8, #12 and #14 were classified as grade IV, indicating elevated instability risks and the need for targeted reinforcement.</div></div>","PeriodicalId":54941,"journal":{"name":"International Journal of Rock Mechanics and Mining Sciences","volume":"194 ","pages":"Article 106214"},"PeriodicalIF":7.0,"publicationDate":"2025-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144596443","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}

{"title":"Dynamic mode III fracture behaviors in shale: Unraveling the controlling role of bedding structures through experimental characterization and theoretical insights","authors":"Zelin Yan ,&nbsp;Jidong Jin ,&nbsp;Jianxiang Wang ,&nbsp;Mingdong Wei ,&nbsp;Feng Dai ,&nbsp;Yi Liu","doi":"10.1016/j.ijrmms.2025.106211","DOIUrl":"10.1016/j.ijrmms.2025.106211","url":null,"abstract":"<div><div>Understanding the dynamic cracking mechanism of shale poses fundamental in the hydraulic fracturing engineering and controllable shock wave fracturing technique for shale oil and gas exploitation. Despite its importance, existing studies mainly focus on mode I and mode II fracture, experiments on the dynamic mode III fracture behaviors of shale remains scarce. In this study, using the novel axially notched flattened Brazilian disc, we systematically characterized the quasi-static and dynamic mode III fracture behaviors of Lushan shale and compared the rate-dependent anisotropic mode I, mode II and mode III fracture toughness. Experimental results show that the <em>K</em>_IIId values are slightly smaller than <em>K</em>_IId values, while significant larger than <em>K</em>_Id values of shale. The dynamic fracture toughness that penetrating the shale bedding plane is always higher than that along the shale bedding plane. Furthermore, we quantitatively analyzed the rate-dependent spatio-temporal mode III fracture morphology characteristics of shale by fractal dimension and joint roughness coefficient (<em>JRC</em>). The results indicate that the Arrester orientation samples exhibit rougher fracture surface and higher loading rate can reduce the roughness. Interestingly, two types of unconventional mode III fracture behaviors that violate the classical mode III fracture patterns of isotropic solids are firstly observed in shale: the ubiquitous mode III crack front segmentation phenomenon vanishes in the Short-transverse orientation and the famous facet coarsening phenomenon is suppressed in the Arrester orientation. Finally, these unconventional mode III fracture behaviors of shale are theoretically predicted and interpreted using an anisotropic strength criterion. The predicted facet tilting angle agrees well with the experimental results. Our findings highlight that the mode III fracture behaviors of shale are controlled by the bedding structure and loading rate. These results may hold significant implication for guiding the dynamic fracturing of shale reservoir using the controllable shock wave fracturing technique.</div></div>","PeriodicalId":54941,"journal":{"name":"International Journal of Rock Mechanics and Mining Sciences","volume":"194 ","pages":"Article 106211"},"PeriodicalIF":7.0,"publicationDate":"2025-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144587724","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}

{"title":"CO2 phase fluctuation-induced topological damage enhances shale strength","authors":"Changliang Wu ,&nbsp;Hongjian Zhu ,&nbsp;Yiwen Ju ,&nbsp;Zongquan Hu ,&nbsp;Yanjun Lu ,&nbsp;Ali Raza ,&nbsp;Jianchao Cai","doi":"10.1016/j.ijrmms.2025.106206","DOIUrl":"10.1016/j.ijrmms.2025.106206","url":null,"abstract":"<div><div>Pressure drops and low-temperature fracture zones readily induce CO₂ phase-state transitions, significantly affecting methane recovery and storage safety. This study conducted a series of CO₂ phase-transition erosion experiments coupled with triaxial cyclic loading-unloading tests under temperature-confining pressure (<strong><em>T-P</em></strong>_{<em><strong>c</strong></em>}) conditions. Key findings include: (1) Shale structural discontinuity is exacerbated by cyclic CO₂ phase transitions under loading, which cause physicochemical damage. As a result, the macroscopic mechanical characteristics and damage variables (quantified by dissipated energy and stiffness degradation) become disconnected. We show that, contrary to the conventional assumption that damage always weakens materials, the controlled damage distribution can counterintuitively improve mechanical performance. (2) To appropriately define damage evolution, we created a multiscale spatial-structure complexity evolution model (<strong><em>D</em>_<em>T</em></strong>) based on the inherent nature of damage: the geometric complexity evolution of structural defects. The dynamics of damage progression are accurately quantified by this model. The system produces enough microdefects to induce distributed damage when <strong><em>D</em>_<em>T</em></strong> exceeds 0.67, which enhances fatigue resistance. (3) A higher phase-transition frequency concurrently decreases permeability (P₂ &lt; 0.0469 μm²) and increases porosity (P₁ &gt; 6.65 %). This reduces pore connection and promotes the spread of distinct micro-defects within the spatial structure of shale. Paradoxically, macroscopic mechanical characteristics are significantly improved by such intensified damage. (4) A fundamental shift in the mechanism of shale damage is induced by cyclic loading with CO₂ phase transitions (15 h/cycle). Our results reveal that static damage parameters are insufficient for predicting macroscopic mechanical responses. Importantly, the spatial configuration of internal damage patterns is the major factor driving macroscopic strength evolution in rocks.</div></div>","PeriodicalId":54941,"journal":{"name":"International Journal of Rock Mechanics and Mining Sciences","volume":"194 ","pages":"Article 106206"},"PeriodicalIF":7.0,"publicationDate":"2025-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144580853","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}