International Journal of Rock Mechanics and Mining Sciences最新文献

{"title":"Experimental study on the permeability characteristics of reconsolidated salt: Effects of gas and confining pressure","authors":"Zongze Li ,&nbsp;Jinyang Fan ,&nbsp;Yanfei Kang ,&nbsp;Yang Zou ,&nbsp;Marion Fourmeau ,&nbsp;Jie Chen ,&nbsp;Deyi Jiang ,&nbsp;Daniel Nelias","doi":"10.1016/j.ijrmms.2026.106424","DOIUrl":"10.1016/j.ijrmms.2026.106424","url":null,"abstract":"<div><div>Reconsolidated salt, formed from crushed halite under compaction, is a promising buffer and sealing material for deep geological repositories of high-level radioactive waste (HLW) because of its low permeability and self-healing properties. This study investigated the gas permeability behavior of reconsolidated salt with varying porosities under different confining pressures and inlet gas pressures using nitrogen gas. Based on nuclear magnetic resonance (NMR) technology, the pore structure of reconsolidated salt specimens with different porosities was tested and imaged. The experimental results demonstrate that gas permeability decreases with increasing gas and confining pressures, with gas pressure having a more pronounced effect. The observed permeability‒pressure relationship is attributed primarily to the Klinkenberg effect, with gas slippage along pore walls enhancing the measured permeability under low-pressure conditions. Using the Klinkenberg correction, the absolute permeability values of reconsolidated salt were derived, reaching as low as 10⁻¹⁹ m² in low-porosity samples. These values are significantly lower than the apparent gas permeability, indicating excellent sealing performance comparable to or superior to that of bentonite. A logarithmic relationship between the absolute permeability and confining pressure was established, providing a quantitative basis for permeability prediction under repository stress conditions. NMR imaging results indicate that with decreasing porosity, the connectivity between pores also gradually diminishes. Additionally, the slip factor was found to increase with increasing confining pressure, underscoring the evolving influence of pore geometry on gas transport mechanisms. Permeability of reconsolidated granular salt decreases with porosity following a power-law relationship, and the healing supports its sealing effectiveness. This study provides essential data and theoretical insights for evaluating the long-term sealing performance of reconsolidated salt in salt-based HLW repositories.</div></div>","PeriodicalId":54941,"journal":{"name":"International Journal of Rock Mechanics and Mining Sciences","volume":"199 ","pages":"Article 106424"},"PeriodicalIF":7.5,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146039328","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":"Exclusion-dependent percolation threshold of non-convex pores and permeability of porous media","authors":"Wenxiang Xu ,&nbsp;Li Wang ,&nbsp;Dingcheng Dai ,&nbsp;Jiaping Liu ,&nbsp;Jinyang Jiang","doi":"10.1016/j.ijrmms.2026.106417","DOIUrl":"10.1016/j.ijrmms.2026.106417","url":null,"abstract":"<div><div>Intricate morphologies of pores have great influences on the percolation threshold of pore space and even the permeability of porous media. Despite extensive efforts to numerically explore the large design space for continuum percolation models of pore space constituted by overlapping objects with rich convexities and their impacts on the permeability, there is a critical knowledge gap on our understanding of the effect of nature of non-convex pore on the percolation threshold and permeability of porous media. This missing understanding hinders the precise evaluation of sewage transport in marine and soil, the durability optimization of hydropower dam, and the fast development of oil and shale gas exploitation. In this work, we develop and validate a high-fidelity numerical description to bridge this knowledge gap. Our description contains three major powerful models. Starting from a 3D morphology reconstruction of realistic surface of non-convex pore, we propose a mathematically-controllable parameterized method to realize arbitrary-shaped pore. Accordingly, the excluded volume of non-convex pore and its dependence on non-convex morphologies are obtained using large-scale Monte Carlo simulations (LSMCs). Then, we combine LSMCs and finite-size scaling method to accurately determine the long-range percolation threshold of non-convex pore space. By analyzing 311 statistical data for the percolation threshold affected by excluded volume of convex/non-convex objects, a generic exclusion-dependent percolation threshold model is proposed that does not only demonstrate the universality of the excluded-volume theory but is capable of estimating the percolation threshold of overlapping arbitrary-shaped objects from convexity to non-convexity. We also develop a multi-relaxation-time lattice Boltzmann method to precisely capture the permeability of porous media over the entire range of porosities, specifically its non-linear saltation behavior near the percolation threshold of non-convex pore space. Altogether, these results shed fresh light on non-convex pore morphologies that dominate the excluded volume, percolation threshold and permeability. Our description illuminates the universal relationship of “excluded volume-percolation threshold-permeability” in porous media, which in turn can guide the design of geological materials and the pore-level optimization in ways previously unattainable for critical water/gas/oil-energy applications.</div></div>","PeriodicalId":54941,"journal":{"name":"International Journal of Rock Mechanics and Mining Sciences","volume":"199 ","pages":"Article 106417"},"PeriodicalIF":7.5,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145962149","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":"Advanced thermo-hydro-mechanical modelling of Callovo-Oxfordian claystone: Temperature effects and multi-scale applications for geological disposal safety","authors":"M. Souley ,&nbsp;C. De Lesquen ,&nbsp;M.N. Vu ,&nbsp;G. Armand","doi":"10.1016/j.ijrmms.2026.106397","DOIUrl":"10.1016/j.ijrmms.2026.106397","url":null,"abstract":"<div><div>To support the feasibility of the Cigéo deep geological repository, Andra has carried out extensive thermo-hydro-mechanical (THM) investigations on Callovo-Oxfordian (COx) claystone. These investigations combine in-situ experiments conducted at the Meuse/Haute-Marne Underground Research Laboratory (M-HM URL) with detailed laboratory-scale characterisations. This study introduces an enhanced rheological model that integrates temperature-dependent mechanical characteristics derived from recent experimental data. Implemented in COMSOL Multiphysics®, the model is validated against triaxial THM tests at different temperature levels (20°, 40°, 60° and 80 °C), accurately capturing short-term strength degradation and volumetric behaviour transitions under increasing temperature. Long-term behaviour simulations, including simulation of triaxial creep tests at 40° and 60 °C, show excellent agreement with the analytical results, with deviations remaining below 0.1 %. The proposed model was first applied at the underground structures scale to the GCS drift, which serves as a reference case for validating the constitutive models of the COx claystone. The simulation covered a 20-year period, and the results were successfully compared with the convergence measurements recorded since the gallery's excavation. The model is further applied to the HITEC near-field benchmark to assess thermal impacts on the Excavation-induced Fracture Zone (EFZ) surrounding a heat-emitting waste cell. The results confirm the robustness and applicability of the proposed THM framework for large-scale repository design under thermal loading conditions.</div></div>","PeriodicalId":54941,"journal":{"name":"International Journal of Rock Mechanics and Mining Sciences","volume":"199 ","pages":"Article 106397"},"PeriodicalIF":7.5,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145980632","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":"Rockburst in circular openings under varying confining stress: Acoustic emission characteristics and precursors","authors":"Yang Wang ,&nbsp;Murat Karakus ,&nbsp;Dongqiao Liu ,&nbsp;Manchao He ,&nbsp;Yunpeng Guo","doi":"10.1016/j.ijrmms.2026.106418","DOIUrl":"10.1016/j.ijrmms.2026.106418","url":null,"abstract":"<div><div>Rockburst induced by high in-situ stress is a major threat to the stability of underground structures. Among various controlling factors, confining stress plays a decisive role in governing the initiation, development, and intensity of rockburst. In this study, true triaxial rockburst experiments were conducted on sandstone specimens containing a circular hole under five levels of confining stress. The failure process was monitored through real-time video and acoustic emission (AE) techniques. AE energy, entropy, and microcrack mechanisms were analyzed to characterize the evolution of failure. Two precursor indicators, namely variance based on Critical Slowing Down (CSD) theory and the Hurst exponent derived from Rescaled Range (R/S) analysis, were employed to identify early warning signals. Results show that higher confining stress leads to greater energy accumulation, stronger tangential stress concentration, more abrupt failure behavior, and increased damage brittleness. The variance parameter was more sensitive to sudden failure, whereas the Hurst exponent provided earlier indications of instability. A two-stage damage fitting model revealed accelerated damage growth and increased brittleness with rising confining stress. These findings improve the understanding of rockburst evolution under different stress conditions and contribute to the development of more reliable early warning systems for deep underground engineering.</div></div>","PeriodicalId":54941,"journal":{"name":"International Journal of Rock Mechanics and Mining Sciences","volume":"199 ","pages":"Article 106418"},"PeriodicalIF":7.5,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146014876","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":"An interpretable rock mass quality intelligent classification model (IRICM) driven by refined decision rule and its application","authors":"Xiang Wu ,&nbsp;Fengyan Wang ,&nbsp;Jianping Chen ,&nbsp;Mingchang Wang ,&nbsp;Lina Cheng ,&nbsp;Chengyao Zhang ,&nbsp;Junke Xu","doi":"10.1016/j.ijrmms.2026.106430","DOIUrl":"10.1016/j.ijrmms.2026.106430","url":null,"abstract":"<div><div>Rock mass quality classification (RMQC) plays a crucial role in rock mass stability analysis and in the design and construction planning of rock engineering projects. However, current RMQC methods rely on expert experience, which makes it difficult for RMQC to be intelligent, scientific, and interpretable, and is not conducive to understanding rock mass characteristics in engineering applications. Therefore, this study proposes an interpretable rock mass quality intelligent classification model (IRICM) by coupling random forest (RF) and genetic algorithm (GA) to refine decision rules, aiming to enhance the intelligence, scientificity, and interpretability of RMQC. Based on 318 tunnel section data, the RMQC dataset was constructed using rock mass rating (RMR) parameters obtained from field investigations and laboratory experiments. By coupling RF and GA, the rules from all decision trees were selected, combined, and optimized to refine decision rules, achieving a classification accuracy of 87.50 % with only five rules per class. Interpretability analysis of the refined decision rules revealed that rock quality designation (RQD), intact rock strength (IRS), joint spacing (JS), and groundwater (GW) were the most frequently used features, confirming their importance in RMQC. Further analysis using post-hoc interpretability techniques also indicated that RQD, IRS, JS, and GW contributed most significantly to RMQC, especially in distinguishing poor rock mass quality (classes IV and V). The model was applied to the RMQC of tunnels and rock slopes, and the results demonstrated consistency with classification outcomes from the Q, RMR, and geological strength index (GSI) systems, validating its reliability and stability.</div></div>","PeriodicalId":54941,"journal":{"name":"International Journal of Rock Mechanics and Mining Sciences","volume":"199 ","pages":"Article 106430"},"PeriodicalIF":7.5,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146033270","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 response analysis of three-layer anchorage under radial P-wave loading: wave-function expansion for optimal thickness","authors":"Jian Ouyang ,&nbsp;Xiuzhi Shi ,&nbsp;Xianyang Qiu ,&nbsp;Chengxing Zong ,&nbsp;Zongguo Zhang","doi":"10.1016/j.ijrmms.2026.106416","DOIUrl":"10.1016/j.ijrmms.2026.106416","url":null,"abstract":"<div><div>Blasting-induced dynamic loads are a primary risk factor for failure in underground support structures. Based on the wave-function expansion method, this study develops a dynamic response model of a surrounding rock-anchoring agent-bolt system subjected to cylindrical P-wave incidence. A dimensionless dynamic stress concentration factor (DSCF) is introduced to characterize the stress within the system. The influences of blasting source frequency, impact distance, anchoring agent thickness, and material impedance mismatch on the evolution of DSCF are systematically analyzed. Parametric analyses reveal that low-frequency excitation leads to lower and more uniformly distributed DSCF. The thickness and shear modulus of the anchoring agent significantly affect the magnitude and directional distribution of DSCF. The LS-DYNA simulations validate the model's ability to capture wave propagation, interface reflections, and stress concentration, confirming that reflected shear waves govern circumferential stress and make the 90° direction most prone to tensile failure. Physical model tests further verify this trend, with higher 90° strain and stronger internal interface response, supporting the model's engineering applicability. A three-dimensional response surface is established, incorporating frequency, impedance, and thickness. Based on this surface, a quantitative optimization strategy is proposed: within the parameter space examined here, thickness ratios in the range of 1.4–1.8 reduce DSCF, combined with suitable impedance matching, can effectively minimize DSCF under multi-frequency excitation under the adopted model assumptions. This study establishes an analytical framework and validated failure mechanism for radial dynamic stress concentration, and proposes a quantifiable design criterion that enables more reliable optimization of anchorage systems under blasting loads.</div></div>","PeriodicalId":54941,"journal":{"name":"International Journal of Rock Mechanics and Mining Sciences","volume":"199 ","pages":"Article 106416"},"PeriodicalIF":7.5,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145956878","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":"Influence of rock creep on the performance of lined caverns under cyclic pressurization and hydrogen embrittlement","authors":"Chenxi Zhao ,&nbsp;Haiyang Yu ,&nbsp;Zixin Zhang ,&nbsp;Qinghua Lei","doi":"10.1016/j.ijrmms.2026.106401","DOIUrl":"10.1016/j.ijrmms.2026.106401","url":null,"abstract":"<div><div>Lined rock cavern (LRC) technology, known for its remarkable geographical flexibility, stands out as a promising and cost-effective approach to underground hydrogen storage. However, since these caverns are often built in complex geological settings and designed for prolonged operation, evaluating their long-term stability is crucial, which should take into account both the creep of rock masses under fatigue loading and the degradation of the steel lining under hydrogen embrittlement (HE). In this paper, we present a comprehensive numerical analysis of LRCs within fractured rock masses, incorporating the effects of time-dependent viscoelastic deformation in the host rock and HE processes in the steel lining under cyclic pressurization. A novel two-dimensional multiscale model is developed that captures the interactions between the LRC structure and the surrounding fractured rocks to assess the damage and degradation of concrete, rock, and steel components in the LRC system. Our framework uniquely integrates rock viscoelasticity and steel hydrogen embrittlement mechanisms, providing a quantitative means to evaluate the long-term mechanical–chemical interactions. The findings demonstrate that the rock’s viscoelastic behavior significantly impacts the time-dependent integrity of the LRC, with damage progressively accumulating during prolonged operation. Additionally, damage evolution in the concrete lining and rock mass, along with steel degradation, are strongly influenced by pre-existing fractures in the rock mass. While small relaxation times in the viscoelastic response lead to rapid system stabilization, moderate relaxation times can trigger time-dependent stress redistribution and further damage progression. The results also highlight the important effect of HE on LRC performance, especially when the surrounding rock mass is characterized by the presence of interconnected fractures. The insights gained in this study are critical to optimizing the design and ensuring the long-term safe operation of LRCs in the context of sustainable underground hydrogen storage.</div></div>","PeriodicalId":54941,"journal":{"name":"International Journal of Rock Mechanics and Mining Sciences","volume":"199 ","pages":"Article 106401"},"PeriodicalIF":7.5,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145908712","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":"The Cosserat continuum with the hyperbolic Mohr-Coulomb failure surface and its applications to strength problems","authors":"Le Zhang,&nbsp;Hong Zheng","doi":"10.1016/j.ijrmms.2026.106425","DOIUrl":"10.1016/j.ijrmms.2026.106425","url":null,"abstract":"<div><div>In the field of continuum mechanics, the Cauchy continuum model has traditionally held a dominant position. In contrast, the Cosserat continuum model, which serves as a significant complement to the Cauchy model, has primarily been used to address strain softening or to simulate the growth of shear bands. In the limited applications of the Cosserat continuum to strength problems, the elasto-plastic model employed takes the Drucker-Prager criterion as the failure criterion, rather than the Mohr-Coulomb criterion that better captures the failure characteristics of geomaterials. This is largely due to the fact that a non-smooth Mohr-Coulomb yield surface poses substantial challenges for elasto-plastic constitutive integration. To address this issue, this study develops a projection-contraction algorithm based on Gauss-Seidel iteration to implement stress updates within the framework of the Cosserat model, using a hyperbolic Mohr-Coulomb (HMC) criterion as the yield criterion. The Gauss–Seidel Projection-Contraction (GSPC) algorithm eliminates the need to compute the Hessian matrix of the yield function and exhibits superior numerical performance compared to the widely-used return-mapping method. Meanwhile, a displacement control method (DCM) is designed to bring models to the limit equilibrium state. This proposed procedure exhibits superior numerical performance compared to load control method (LCM) based on Newton iteration. Analysis of typical case studies reveals that the proposed method is free from mesh dependency and possesses robust numerical characteristics. In particular, the Cosserat continuum naturally regularizes strain localization in elastic–perfectly plastic problems, and the internal characteristic length significantly influences the thickness of shear bands and the distribution of plastic zones.</div></div>","PeriodicalId":54941,"journal":{"name":"International Journal of Rock Mechanics and Mining Sciences","volume":"199 ","pages":"Article 106425"},"PeriodicalIF":7.5,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146033269","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":"Analysis of seismic potential in a depleted chalk reservoir subject to CO2 injection","authors":"M.R. Hajiabadi,&nbsp;F. Amour,&nbsp;B. Hosseinzadeh,&nbsp;A.C. Cheriki,&nbsp;H. Nick","doi":"10.1016/j.ijrmms.2025.106394","DOIUrl":"10.1016/j.ijrmms.2025.106394","url":null,"abstract":"<div><div>This study presents a multi-scale modelling framework to evaluate fault reactivation risks and seismic potential during CO₂ injection into a highly depleted and deformable chalk reservoir, using the Harald East field in the northern part of the Danish North Sea as a case study. A robust multi-scale Thermo-Hydro-Mechanical (THM) modeling approach is developed to bridge field- and fault-scale processes, supporting fault stability and seismic risk assessment in CO₂ storage. A field-scale coupled flow-geomechanical model is used to screen for critically-stressed faults, while fault-scale simulations investigate slip behaviour using a Mohr-Coulomb frictional model, combined with a rate-dependent frictional model to assess specific potential seismic events. THM analysis under realistic CO₂ injection scenarios reveals that faults remain stable with friction coefficients of 0.6. However, simulations with reduced initial friction coefficients (e.g., 0.27 and 0.36) indicate localized slip risks during both production and injection phases along the plane of one single fault out of a total of 30 faults analysed. As the reservoir repressurizes, the stress regime transitions from normal to reverse faulting, accompanied by a significant reorientation in principal stress. This shift of stress regime causes a progressive rise in shear stress on the fault plane as repressurization continues, resulting in higher slip tendency values and a greater likelihood of seismic reactivation. Besides, the results demonstrate the benefit of a combined field- and fault-scale approach that enhances computational efficiency by restricting detailed analyses to critical faults and critical time throughout the injection period. This work provides a framework for fault stability and seismic risk assessments, offering key insights for the safe implementation of underground CO₂ storage projects.</div></div>","PeriodicalId":54941,"journal":{"name":"International Journal of Rock Mechanics and Mining Sciences","volume":"199 ","pages":"Article 106394"},"PeriodicalIF":7.5,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145941325","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":"Rapidly improving the acid-fracture conductivity in deep and ultra-deep carbonate reservoirs through mineral alteration: a new method","authors":"Xiang Chen ,&nbsp;Zhaoxu Deng ,&nbsp;Pingli Liu ,&nbsp;Tianyu Zhang ,&nbsp;Juan Du ,&nbsp;Hongming Tang ,&nbsp;Haitai Hu ,&nbsp;Xuan Gao ,&nbsp;Zhongxuan Wang ,&nbsp;Xiaotian He","doi":"10.1016/j.ijrmms.2026.106415","DOIUrl":"10.1016/j.ijrmms.2026.106415","url":null,"abstract":"<div><div>Deep and ultra-deep carbonate reservoirs contain abundant geothermal and natural gas resources, and the conductivity of acid-fractured fractures is a critical factor determining the development efficiency of these resources. However, high closure stress and acid-induced damage can lead to fracture closure and conductivity degradation. Mineral alteration refers to the in-situ conversion of existing minerals into new compounds, but the mineral alteration process is currently too slow (72 h). The Na₂HPO₄ + H₃PO₄ buffer solution (PPN) has been preliminarily proven effective in rapidly enhancing rock strength. This study investigated the effects of different acid systems (gelling acid and organic acid) and PPN treatment at 200 °C on the etching morphology, hardness, and fracture conductivity of dense carbonate rocks from two formations: the Mao-kou limestone and the Jialingjiang argillaceous limestone. The experimental results confirm that PPN rapid treatment under ultra-high temperature is effective in enhancing the fracture conductivity under high closure stress, and also reveal its mechanism of action. After 4 h of PPN treatment at 200 °C, the fracture conductivity of the Mao-kou formation and Jialingjiang formation samples increased by factors of 29.4 and 19.0, respectively, compared with untreated samples. Acid dissolution caused the rock's microstructure to transform from being dense and compact to becoming loose, with numerous dissolution pores and micro-fractures. In contrast, PPN treatment converted carbonate minerals on the fracture surfaces in situ into harder hydroxyapatite and repaired acid-induced structural damage, thereby enhancing rock strength and deformation resistance, resulting in smaller fracture-closure displacement under stress. Acid-induced damage reduced the hardness of Mao-kou formation and Jialingjiang formation samples by up to 25.6 % and 36.9 %, respectively. PPN treatment was effective for both limestone and argillaceous limestone, with the maximum increases in rock hardness reaching 39.4 % and 29.8 %, respectively. The organic acid produced a more heterogeneous etching morphology in the argillaceous limestone than the gelling acid did in the limestone. This study provides a new pathway for the rapid construction of high-conductivity fractures in deep and ultra-deep reservoir and efficient energy development.</div></div>","PeriodicalId":54941,"journal":{"name":"International Journal of Rock Mechanics and Mining Sciences","volume":"199 ","pages":"Article 106415"},"PeriodicalIF":7.5,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146014869","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}