International Journal of Rock Mechanics and Mining Sciences最新文献

{"title":"Modeling of thermally driven longitudinal fractures along a vertical well","authors":"Bin Chen ,&nbsp;Quanlin Zhou","doi":"10.1016/j.ijrmms.2024.105942","DOIUrl":"10.1016/j.ijrmms.2024.105942","url":null,"abstract":"<div><div>Fluid injection via a vertical well into a high-temperature formation may induce <em>multiple longitudinal</em> thermal fractures, which may eventually transition to <em>two-wing</em> fractures during fracture propagation, depending on horizontal stress ratio <span><math><mrow><mi>κ</mi></mrow></math></span>. In this study, we develop a plane strain model with radial heat conduction to investigate either two-wing fractures under highly anisotropic stresses <span><math><mrow><msub><mi>κ</mi><mrow><mi>h</mi><mi>a</mi></mrow></msub><mo>≫</mo><mn>1</mn></mrow></math></span> or multiple fractures under isotropic stresses <span><math><mrow><mi>κ</mi><mo>=</mo><mn>1</mn></mrow></math></span>. The coupled dimensionless elasticity equation and criteria of fracture propagation (and <em>arrest</em>) are formulated, discretized, and solved iteratively (with two special algorithms). Two additional critical model parameters are dimensionless effective confining stress <span><math><mrow><mi>T</mi></mrow></math></span> and wellbore radius <span><math><mrow><mi>A</mi></mrow></math></span>. The multiple-fracture solution of dimensionless fracture length <span><math><mrow><mi>L</mi></mrow></math></span>, angular spacing <span><math><mrow><mi>D</mi></mrow></math></span>, and aperture consists of solutions for competitive propagation of fractures with arrests in the near-wellbore region and the subsequent stable propagation of fractures away from the wellbore. Both the multiple-fracture and two-wing-fracture solutions accurately capture the early-time transient and late-time power-law changes with dimensionless time <span><math><mrow><mi>τ</mi></mrow></math></span>, as verified numerically. The late-time fracture propagation follows scaling law <span><math><mi>L</mi><mo>=</mo><mi>f</mi><mfenced><mrow><mi>T</mi><mo>,</mo><mi>A</mi><mo>,</mo><mi>D</mi></mrow></mfenced><msup><mi>τ</mi><mrow><mfenced><mrow><mn>1</mn><mo>−</mo><mn>2</mn><mi>T</mi></mrow></mfenced><mo>/</mo><mn>2</mn></mrow></msup></math></span>. These solutions and scaling laws can be used to well bound a <em>general</em> solution with <span><math><mrow><mn>1</mn><mo>&lt;</mo><mi>κ</mi><mo>&lt;</mo><msub><mi>κ</mi><mrow><mi>h</mi><mi>a</mi></mrow></msub></mrow></math></span> as demonstrated numerically for a geothermal site, for which the maximum fracture length reaches 0.45, 2.71, and 16.42 m in 1, 100 and 10,000 days of cooling, respectively. The applicability of the assumptions used in the theoretical and numerical analysis is discussed.</div></div>","PeriodicalId":54941,"journal":{"name":"International Journal of Rock Mechanics and Mining Sciences","volume":"183 ","pages":"Article 105942"},"PeriodicalIF":7.0,"publicationDate":"2024-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142538896","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 elastoplastic solution for lined hydrogen storage caverns during excavation and operation phases considering strain softening and dilatancy","authors":"Kai Qiu ,&nbsp;Shuchen Li ,&nbsp;Zhongzhong Liu ,&nbsp;Meng Yuan ,&nbsp;Shisen Zhao ,&nbsp;Zeen Wan","doi":"10.1016/j.ijrmms.2024.105949","DOIUrl":"10.1016/j.ijrmms.2024.105949","url":null,"abstract":"<div><div>Underground hydrogen energy storage (UHES) in lined rock caverns (LRCs) represents a crucial solution to the challenge of unstable and uneven clean energy generation. Nevertheless, the attainment of enhanced storage efficiencies frequently necessitates the utilization of elevated hydrogen storage pressures. Consequently, a comprehensive understanding of the elastic-plastic mechanical response of surrounding rock under hydrogen pressure is of paramount importance for ensuring the safety of UHES. In this study, an elastoplastic solution of LRCs during construction and operation phases is established. Two essential phenomena affecting the post-peak mechanical responses of surrounding rock, strain softening and dilatancy, are coupled into the plastic solution. A computational process is developed and its accuracy is validated through comparison with numerical models. The influence of surrounding rock quality parameters, strain softening and dilatancy parameters, concrete quality parameters and hydrogen pressure on the radius of the plastic softening zone (<em>R</em>_<em>s</em>) and plastic residual zone (<em>R</em>_<em>r</em>) were analyzed. Results show that higher surrounding rock quality can effectively reduce both <em>R</em>_<em>s</em> and <em>R</em>_<em>r</em>. Nevertheless, when the surrounding rock quality already reaches a high standard, such as <em>c</em>₁ &gt; 3.5 MPa, <em>φ</em>₁ &gt; 65°, or <em>E</em> &gt; 55 MPa, it becomes inefficient to overly pursue further improvements in the surrounding rock quality. Furthermore, the strain softening and dilatancy phenomena only affect <em>R</em>_<em>r</em>. Additionally, the concrete lining with higher stiffness can share a larger portion of the hydrogen pressure, thus reducing both <em>R</em>_<em>s</em> and <em>R</em>_<em>r</em>. Notably, When the elastic modulus of concrete increases from 20 MPa to 40 MPa, <em>R</em>_<em>r</em> decreases by 31.98 % and <em>R</em>_<em>s</em> decreases by 20.96 %. Moreover, the critical hydrogen pressure (<em>P</em>_<em>Hcr</em>) at which the surrounding rock begins to enter a plastic state is proportional to the ground stress (<em>P</em>₀). Specifically, when <em>P</em>₀ is increased sequentially from 2.5 MPa to 3.0 MPa and 3.5 MPa, <em>P</em>_<em>Hcr</em> sequentially becomes 2.4 MPa, 4.0 MPa, and 5.0 MPa. The findings presented in this study contribute to improving the safety of LRCs during construction and operation.</div></div>","PeriodicalId":54941,"journal":{"name":"International Journal of Rock Mechanics and Mining Sciences","volume":"183 ","pages":"Article 105949"},"PeriodicalIF":7.0,"publicationDate":"2024-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142538808","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 fault activation-shearing-sliding peridynamic model exploring the role of static and kinetic frictional contacts","authors":"Zhen Yang ,&nbsp;HanYi Wang ,&nbsp;Mukul Sharma ,&nbsp;Erdogan Madenci","doi":"10.1016/j.ijrmms.2024.105946","DOIUrl":"10.1016/j.ijrmms.2024.105946","url":null,"abstract":"<div><div>Understanding fault dynamics is essential for comprehending the underlying mechanisms of seismic events. This study introduces a novel fault activation-shearing-sliding model within a peridynamic (PD) framework, characterized by distinctly defined static and kinetic frictional behaviors. Static friction bonds are developed to sustain normal forces perpendicular to the fault plane and to manage tangential frictional forces along the fault's geometry. The failure of these bonds is directly linked to fault activation, while the ensuing sliding phase is governed by a short-range kinetic friction model. Additionally, an adaptive identification method is proposed to accurately determine local unit normal vectors on arbitrarily shaped contact surfaces. The effectiveness and applicability of the model are validated through fault activation and plate sliding friction tests. The model is further utilized to investigate the effects of local geometry, roughness, and friction coefficients on fault behavior, with comparisons to experimental results. Observations indicate that the dominant factors influencing fault shear resistance vary across stages, primarily involving static friction during activation, compaction deformation during shearing, and kinetic friction during sliding. When shear resistance is primarily governed by friction, it exhibits heightened sensitivity to various shear forces, including those from indirect loading disturbances.</div></div>","PeriodicalId":54941,"journal":{"name":"International Journal of Rock Mechanics and Mining Sciences","volume":"183 ","pages":"Article 105946"},"PeriodicalIF":7.0,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142535664","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":"Geothermal fluid extraction and injection-related fracture slip susceptibility and seismicity in naturally fractured rocks","authors":"Wenzhuo Cao ,&nbsp;Sevket Durucan ,&nbsp;Ji-Quan Shi ,&nbsp;Anna Korre ,&nbsp;Thomas Ratouis ,&nbsp;Vala Hjörleifsdóttir","doi":"10.1016/j.ijrmms.2024.105939","DOIUrl":"10.1016/j.ijrmms.2024.105939","url":null,"abstract":"<div><div>Understanding fracture slip susceptibility in geothermal reservoirs is central to the control of fluid injection-induced seismicity. To investigate the role of regional fracture systems on induced seismicity, a coupled thermo-hydro-mechanical (THM) model containing fracture networks was developed, which features direct coupling between different physics for explicit fractures, fractured rocks (porous matrix blocks with small-scale fractures) and their interactions, as well as indirect coupling through changes of material properties, such as stress-dependent fracture and rock permeabilities. The model was applied to simulate geothermal fluid extraction and re-injection in a natural fracture system comprised of three dominant fracture sets at the Hellisheiði geothermal field over a 10-year period (2011–2021), utilising field recorded monthly production and re-injection rates. Based on the model results, the slip susceptibility of regional fracture systems was examined under reservoir conditions before and after the start of fluid re-injection across different time scales, i.e., over short (1 month), intermediate (1 year) and long-term (10 years). Two model scenarios, one with cooling contraction and one without, were considered to examine the relative contribution of cooling contraction and fluid overpressure on fracture slip susceptibility. Results have shown that fracture networks act as preferential fluid flow paths that influence fluid pressure and stress distribution and fracture slip susceptibility in geothermal reservoirs. NE-SW and N-S trending fractures at Hellisheiði are susceptible to slippage before the start of fluid re-injection. During fluid re-injection, the distribution of fractures with enhanced slip susceptibility gradually shifts from surrounding the re-injection region to forming a two-lobed pattern in the fault-normal direction around the re-injection region, indicating the dominant role of cooling contraction over fluid overpressure on the fracture slip susceptibility in the intermediate- and long-term.</div></div>","PeriodicalId":54941,"journal":{"name":"International Journal of Rock Mechanics and Mining Sciences","volume":"183 ","pages":"Article 105939"},"PeriodicalIF":7.0,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142535663","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"3D in-situ stress prediction for shale reservoirs based on the CapsNet-BiLSTM hybrid model","authors":"Fen Lyu ,&nbsp;Junping Liu ,&nbsp;Li Chen ,&nbsp;Bocheng Tao ,&nbsp;Xingye Liu","doi":"10.1016/j.ijrmms.2024.105937","DOIUrl":"10.1016/j.ijrmms.2024.105937","url":null,"abstract":"<div><div>In-situ stress is essential in shale reservoir fracturing, driving oil and gas migration and informing wellbore stability and drilling optimization. The accurate prediction of 3D in-situ stress is inseparable from seismic data. However, existing methods predominantly rely on empirical formulas or simplified assumptions, which limit their accuracy in representing the real distribution of in-situ stress. Furthermore, these methods often predict in-situ stress from a single factor, leading to high uncertainty. To address these, we propose a method for predicting 3D in-situ stress that leverages a hybrid Capsule Network-Bidirectional Long Short-Term Memory (CapsNet-BiLSTM) model. This approach takes into account various factors, such as geological features and seismic attributes, to achieve more accurate predictions. First, we analyze the structural characteristics of shale formations and use rock petrophysical knowledge to reasonably filter input data, eliminating the impact of redundant parameters on in-situ stress prediction. Then, to overcome the limitations of traditional deep learning models in capturing correlations within complex data structures, we construct a CapsNet-BiLSTM network model. This model integrates the spatial relationship modeling capability of CapsNet and the temporal modeling capability of BiLSTM, better accounting for the anisotropic features and temporal sequence information of shale reservoirs. Applying this method to a study area in the Sichuan Basin demonstrates that the constructed CapsNet-BiLSTM hybrid model accurately predicts in-situ stress values, effectively capturing the spatial distribution patterns of complex in-situ stress within shale reservoirs, thus proving the effectiveness and potential of our method in geological engineering applications for shale oil and gas reservoirs. This hybrid model-based prediction method not only improves the accuracy of in-situ stress prediction but also provides a valuable methodological and technical support for scientific research and engineering practices in related fields.</div></div>","PeriodicalId":54941,"journal":{"name":"International Journal of Rock Mechanics and Mining Sciences","volume":"183 ","pages":"Article 105937"},"PeriodicalIF":7.0,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142535662","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 role of annealing and grain boundary controls on the mechanical properties of limestones and marbles","authors":"Rui Zhang ,&nbsp;Paul A. Bosomworth ,&nbsp;Juliane Weber ,&nbsp;Jan Ilavsky ,&nbsp;Si Athena Chen ,&nbsp;Alexis Flores-Betancourt ,&nbsp;Elliot Paul Gilbert ,&nbsp;Jitendra Mata ,&nbsp;Mark L. Rivers ,&nbsp;Peter J. Eng ,&nbsp;Lawrence M. Anovitz","doi":"10.1016/j.ijrmms.2024.105926","DOIUrl":"10.1016/j.ijrmms.2024.105926","url":null,"abstract":"<div><div>Chemical and mechanical processes are coupled in many geological and geochemical environments. Reactive processes anneal defects and restructure grain boundaries, modifying their elastic properties, levels of internal friction, wave propagation rates and fracture behaviors. The nature of these changes is, however, contingent on the initial state of the rock. In this study, impulse excitation was used to measure changes in mechanical properties as a function of dry and steam heating time at 300 °C for three carbonate rocks: Carrara marble, Carthage marble (Burlington Limestone), and Texas Cream limestone (Edwards limestone), with initial porosities of about 1 %, 3 %, and 27 %, respectively. Frequency-dependent phenomena along with mineral recrystallization were observed. This was coupled with small-angle X-ray and neutron scattering analysis to determine the relationship between changes in bulk mechanical and microstructural properties. An observed decrease in both the Young's and shear moduli in the experimental limestones as a function of heating time reflects and quantifies a reduction in the stiffness of the rock due to annealing. The internal friction of the samples first increases then decreases with reaction time, reflecting defect annealing, but this was balanced against grain boundary dissolution apparently driven by condensation of steam in the confined grain-boundary environment. This suggests an increase in the boiling point under confinement leading to dissolution, increased porosity and widening of the grain boundaries. In addition, comparison of small-angle X-ray and neutron scattering results suggests that it is inappropriate to assume that pores are empty for quantitative analysis of typical small-angle scattering samples.</div></div>","PeriodicalId":54941,"journal":{"name":"International Journal of Rock Mechanics and Mining Sciences","volume":"183 ","pages":"Article 105926"},"PeriodicalIF":7.0,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142535665","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 energy-driven crushing-plasticity coupling model for grain crushing in porous rocks","authors":"Yaolan Tang ,&nbsp;Jianchun Li ,&nbsp;Dapeng Wang ,&nbsp;Congying Li ,&nbsp;Chunshun Zhang","doi":"10.1016/j.ijrmms.2024.105931","DOIUrl":"10.1016/j.ijrmms.2024.105931","url":null,"abstract":"<div><div>This research develops an energy-driven constitutive model designed to tackle the complex phenomenon of grain crushing in porous rocks. Initially, a novel coupled relationship is proposed to integrate various energy dissipation mechanisms, including both plastic and crushing effects, using spherical polar coordinates. This approach results in a robust coupling of energy dissipation, providing a comprehensive depiction of the influence of grain crushing on plastic deformation. An energy-based yield criterion is then formulated by comparing elastic potential energy contours with experimental findings, and the behaviour of crushing hardening is examined through energy evolution. Flow rules are subsequently derived, both independently and with consideration of plasticity-crushing coupling. Finally, validation against a range of experimental tests highlights the model's versatility. The proposed model enhances the understanding of rock-crushing issues from an energy perspective and demonstrates simplicity with only 4 or 5 easily calibrated parameters.</div></div>","PeriodicalId":54941,"journal":{"name":"International Journal of Rock Mechanics and Mining Sciences","volume":"183 ","pages":"Article 105931"},"PeriodicalIF":7.0,"publicationDate":"2024-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142535670","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":"Numerical simulation on multi-well fracturing considering multiple thin layers in vertical direction","authors":"Yunpeng Wang ,&nbsp;Tiankui Guo ,&nbsp;Ming Chen ,&nbsp;Xuliang Jia ,&nbsp;Dingwei Weng ,&nbsp;Zhanqing Qu ,&nbsp;Zunpeng Hu ,&nbsp;Bo Zhang ,&nbsp;Jiwei Wang","doi":"10.1016/j.ijrmms.2024.105951","DOIUrl":"10.1016/j.ijrmms.2024.105951","url":null,"abstract":"<div><div>Multiwell fracturing is a key technology for developing shale gas and shale oil reservoirs. In this study, a multiple planar 3D (PL3D) fracture simulator that can capture multiple thin layers was developed to examine the propagation of multiple fractures during multicluster fracturing in multiple horizontal wells. The simulator considers multiple thin layers in the vertical direction. The results of the model are validated against the analytical solution of a single radial fracture and the implicit level set algorithm (ILSA). Using the simulator, a series of numerical simulations based on the field case are performed to investigate the fracture propagation mechanism of multiwell fracturing. The completion sequence, well placement pattern, well spacing, and cluster spacing are investigated to optimize the treatment parameters. The effective fracture area is used to quantitatively describe the stimulation effect. The adaptability of the completion sequence and well placement pattern is also analysed from the perspective of “frac hits”. The results show that the completion sequence has a critical influence on the stimulation effect and fracture geometry. From the perspective of avoiding “frac-hit” fractures, fracturing the low-stress layer can form an “artificial stress barrier”, which slightly protects the well from interference from other fractures. The staggered well pattern is better than the stacked well pattern. Compared with the stacked pattern, the staggered pattern can reduce the overlap area of fractures by 80 %, which greatly reduces the probability of “frac-hits”. With increasing well spacing from 200 m to 500 m, the fracture area increases by 25 %, and the degree of uneven stimulation between the two pay zones also increases by 6 %. Considering that a small well spacing is prone to “frac hits”, a large well spacing leads to an unstimulated area between two wells, and a 350 m well spacing is optimal. The effective fracture area decreases slightly with increasing perforation cluster spacing, but the fracture geometry becomes much more regular. The results can be helpful for the field design of multiwell fracturing.</div></div>","PeriodicalId":54941,"journal":{"name":"International Journal of Rock Mechanics and Mining Sciences","volume":"183 ","pages":"Article 105951"},"PeriodicalIF":7.0,"publicationDate":"2024-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142535669","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":"Exposure behavior and drilling efficiency of basalt fiber composite impregnated diamond bits in hard granite","authors":"Yinlong Ma ,&nbsp;Jie Ren ,&nbsp;Qingquan Zhou","doi":"10.1016/j.ijrmms.2024.105950","DOIUrl":"10.1016/j.ijrmms.2024.105950","url":null,"abstract":"<div><div>Impregnated diamond bits (IDBs) are widely used for drilling in hard formations. To improve the drilling efficiency and exposure behavior of IDBs in granite, three types of Cu-based basalt fiber (BF) composite IDBs were designed and prepared by using the medium-frequency induction hot-pressing and sintering method, in which 0 wt% BF and 25 vol% diamond were used in 0BF25D IDB, 1 wt% BF and 25 vol% diamond were used in 1BF25D IDB, 1 wt% BF and 20 vol% diamond were used in 1BF20D IDB. The drilling efficiency of each IDB was tested under different drilling pressures (WOB), and the exposure behavior of IDBs was investigated by scanning electron microscopy and ultra field microstructural characterization. Results show that drilling granite with grade 9 drillability, low drilling pressure can drill successfully with the addition of BF. The average rate of penetration (ROP) of 1BF20D IBD under 6 kN WOB was 4.78 m/h, which was improved by 60 %∼80 %, energy consumption decreased by 66 % for each meter, torque (TOB) decreased, and rotational speed (RPM) was more stable during the drilling process. The addition of BF and reasonable diamond concentration enhanced the holding power of the diamond which promoted the exposure of the diamond. The average exposed height of the diamond in 1BF20D IDB reached 121.2 μm with 22 %–29 % of the whole diamond.</div></div>","PeriodicalId":54941,"journal":{"name":"International Journal of Rock Mechanics and Mining Sciences","volume":"183 ","pages":"Article 105950"},"PeriodicalIF":7.0,"publicationDate":"2024-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142535789","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":"Determination of the REV size for heterogeneous rocks with different grain sizes: Deep learning and numerical approaches","authors":"Lei Peng ,&nbsp;Mingyao Li ,&nbsp;Jianping Zuo ,&nbsp;Dejun Liu ,&nbsp;Jena Jeong","doi":"10.1016/j.ijrmms.2024.105940","DOIUrl":"10.1016/j.ijrmms.2024.105940","url":null,"abstract":"<div><div>Accurate determination of the representative elementary volume (REV) size plays a pivotal role in analysing the mechanical properties and failure processes of heterogeneous rocks in complex engineering environments. In this study, a novel microstructure modelling strategy (NMMS) for determining the REV size is proposed by combining deep learning and an improved phase-field method (PFM). Micro- and macroscale experiments are systematically conducted to determine the real microstructural characteristics and mechanical properties of heterogeneous rocks with different grain sizes. On the basis of this experimental evidence, geometric models of different sizes were reconstructed through deep learning to avoid the limitations of human-based methods, and an improved PFM was used for numerical calculations. These models were then employed to perform numerical tests under uniaxial loading conditions, and the coefficient of variation was introduced to determine the REV size of heterogeneous rocks with different grain sizes. The research findings indicate that the final REV size is the maximum value of the REVs defined by the evaluation properties within an acceptable coefficient of variation. At a criterion of 5% for the coefficient of variation, the REV sizes are 60 mm<span><math><mo>×</mo></math></span>60 mm, 70 mm<span><math><mo>×</mo></math></span>70 mm, and 90 mm<span><math><mo>×</mo></math></span>90 mm for fine-medium-grained (FMG), medium-grained (MG), and coarse-grained (CG) rocks, respectively. Furthermore, the REV determined by the NMMS was applied to investigate the effects of microstructure on macromechanical properties and damage evolution under triaxial loading conditions. The numerical results show that the NMMS can accurately predict the macromechanical properties and microcracking patterns of heterogeneous rocks, especially the intracrystalline cracks in feldspar, the interfacial cracks in gravel, and the “voids” of cracks in biotite. This research can provide some basic references for the optimal choice of the REV size of heterogeneous rocks.</div></div>","PeriodicalId":54941,"journal":{"name":"International Journal of Rock Mechanics and Mining Sciences","volume":"183 ","pages":"Article 105940"},"PeriodicalIF":7.0,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142535666","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}