International Journal of Rock Mechanics and Mining Sciences最新文献_第2页

Asymmetric failure mechanisms of anisotropic shale under direct shear 各向异性页岩在直接剪切作用下的非对称破坏机制

IF 7 1区工程技术 Q1 ENGINEERING, GEOLOGICAL

International Journal of Rock Mechanics and Mining Sciences

Pub Date : 2024-11-01 DOI: 10.1016/j.ijrmms.2024.105941

Chunfeng Ye , Heping Xie , Fei Wu , Jianjun Hu , Li Ren , Cunbao Li

This study performed mechanical tests and monitored acoustic emissions (AE) in shale samples with six bedding layer orientations (β = 0°, 30°, 60°, 90°, 120°, and 150°) to investigate the progressive damage mechanisms under direct shear. The results revealed that the peak shear load (P_cr), crack initiation threshold (P_ci), crack damage threshold (P_cd), and cumulative AE count exhibited an approximate M-shaped trend as the bedding angle increased. The P_ci, P_cd, and P_cr values were minimal for shale specimens with β = 0°, P_cd and P_cr were maximal at β = 150° (followed by β = 60°), and P_ci reached the maximum at β = 60°. Thus, shale exhibits complex and asymmetric mechanical behavior under direct shear, a phenomenon seldom documented. The three-dimensional spatiotemporal evolution of the AE, evolution of b-values, peak frequency distribution, and the rise angle-average frequency (RA-AF) indicated that the microscale mechanism governing the asymmetric progressive failure of anisotropic shale under direct shear involved significant asymmetry in the formation type and scales of cracks. The AE characteristics of anisotropic shale were analyzed using multifractal theory. The width of the multifractal spectrum, Δθ, accurately reflected the anisotropic characteristics of the AE time series. Moreover, the variation in the fractal dimension, Δf, indicated that the different probabilities of microcracks with high AE energy are the fundamental cause of the shale's asymmetric failure.

本研究对六种垫层方向（β = 0°、30°、60°、90°、120°和 150°）的页岩样品进行了力学测试和声发射（AE）监测，以研究直接剪切作用下的渐进破坏机制。结果表明，峰值剪切载荷（Pcr）、裂纹起始阈值（Pci）、裂纹损伤阈值（Pcd）和累积 AE 计数随着垫层角度的增加呈现近似 M 型的趋势。在 β = 0° 时，页岩试样的 Pci、Pcd 和 Pcr 值最小；在 β = 150° 时，Pcd 和 Pcr 最大（其次是 β = 60°）；在 β = 60° 时，Pci 达到最大值。因此，页岩在直接剪切作用下表现出复杂的非对称力学行为，这种现象很少见诸文献。AE 的三维时空演变、b 值演变、峰值频率分布和上升角度-平均频率（RA-AF）表明，各向异性页岩在直接剪切作用下的非对称渐进破坏的微观机制涉及裂缝形成类型和规模的显著非对称性。利用多分形理论分析了各向异性页岩的 AE 特性。多分形谱宽度 Δθ 准确地反映了 AE 时间序列的各向异性特征。此外，分形维数 Δf 的变化表明，高 AE 能量产生微裂缝的不同概率是页岩非对称破坏的根本原因。

{"title":"Asymmetric failure mechanisms of anisotropic shale under direct shear","authors":"Chunfeng Ye , Heping Xie , Fei Wu , Jianjun Hu , Li Ren , Cunbao Li","doi":"10.1016/j.ijrmms.2024.105941","DOIUrl":"10.1016/j.ijrmms.2024.105941","url":null,"abstract":"<div><div>This study performed mechanical tests and monitored acoustic emissions (AE) in shale samples with six bedding layer orientations (<em>β</em> = 0°, 30°, 60°, 90°, 120°, and 150°) to investigate the progressive damage mechanisms under direct shear. The results revealed that the peak shear load (<em>P</em><sub><em>cr</em></sub>), crack initiation threshold (<em>P</em><sub><em>ci</em></sub>), crack damage threshold (<em>P</em><sub><em>cd</em></sub>), and cumulative AE count exhibited an approximate M-shaped trend as the bedding angle increased. The <em>P</em><sub><em>ci</em></sub>, <em>P</em><sub><em>cd</em></sub>, and <em>P</em><sub><em>cr</em></sub> values were minimal for shale specimens with <em>β</em> = 0°, <em>P</em><sub><em>cd</em></sub> and <em>P</em><sub><em>cr</em></sub> were maximal at <em>β</em> = 150° (followed by <em>β</em> = 60°), and <em>P</em><sub><em>ci</em></sub> reached the maximum at <em>β</em> = 60°. Thus, shale exhibits complex and asymmetric mechanical behavior under direct shear, a phenomenon seldom documented. The three-dimensional spatiotemporal evolution of the AE, evolution of <em>b</em>-values, peak frequency distribution, and the rise angle-average frequency (RA-AF) indicated that the microscale mechanism governing the asymmetric progressive failure of anisotropic shale under direct shear involved significant asymmetry in the formation type and scales of cracks. The AE characteristics of anisotropic shale were analyzed using multifractal theory. The width of the multifractal spectrum, Δ<em>θ</em>, accurately reflected the anisotropic characteristics of the AE time series. Moreover, the variation in the fractal dimension, Δ<em>f</em>, indicated that the different probabilities of microcracks with high AE energy are the fundamental cause of the shale's asymmetric failure.</div></div>","PeriodicalId":54941,"journal":{"name":"International Journal of Rock Mechanics and Mining Sciences","volume":"183 ","pages":"Article 105941"},"PeriodicalIF":7.0,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142552424","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}

引用次数: 0

Rock fragmentation of simulated transversely isotropic rocks under static expansive loadings 在静态膨胀荷载作用下模拟横向各向同性岩石的碎裂情况

IF 7 1区工程技术 Q1 ENGINEERING, GEOLOGICAL

International Journal of Rock Mechanics and Mining Sciences

Pub Date : 2024-11-01 DOI: 10.1016/j.ijrmms.2024.105944

Chundong Shi , Wen Nie , Guowei Ma , Jiangyong Sun , Junlin Wang , Li Wang

Rock fragmentation is a critical process for mineral extraction and for mitigating overstressed rock in geotechnical applications. In this study, 3D-printed concrete was used to simulate the stratified rock mass, and experimental and numerical methods were employed to investigate crack propagation under static expansive loadings in transversely isotropic rocks. Two types of cracks were observed in the experiments: P-type (a crack propagates primarily along the weak layer) and T-type (a crack propagates across the weak layers) cracks. The findings revealed that the orientation of layers significantly influenced the initiation and propagation of cracks, with P-type cracks commonly observed in simpler P-P mode fragmentations and more complex P-P-T modes emerging under higher expansive loadings. P-T-T modes were characterized by the simultaneous presence of the T-type crack after an initial P-type crack. The AE energy levels in the P-P-T and P-T-T modes were much higher than those in the P-P mode. 2D-DDA models were further built to understand the effects of the loading scales, layer angles, and locations of weak layers on the cracking sequences. The results provided detailed insights into stress evolutions and the impact of expansive loadings on crack initiation and propagation.

岩石破碎是矿物开采和缓解岩土工程应用中岩石应力过大的关键过程。本研究使用三维打印混凝土模拟分层岩体，并采用实验和数值方法研究横向各向同性岩石在静态膨胀荷载作用下的裂纹扩展。实验中观察到两种类型的裂缝：P 型裂缝（裂缝主要沿软弱层扩展）和 T 型裂缝（裂缝跨越软弱层扩展）。研究结果表明，岩层的走向对裂缝的产生和扩展有很大影响，P 型裂缝通常出现在较简单的 P-P 模式碎裂中，而在较高的膨胀荷载下，则会出现更复杂的 P-P-T 模式。P-T-T 模式的特点是在初始 P 型裂纹之后同时出现 T 型裂纹。P-P-T 和 P-T-T 模式的 AE 能级远高于 P-P 模式。我们进一步建立了二维-DDA 模型，以了解加载尺度、层角和薄弱层位置对开裂序列的影响。研究结果详细揭示了应力演变以及膨胀荷载对裂纹萌生和扩展的影响。

{"title":"Rock fragmentation of simulated transversely isotropic rocks under static expansive loadings","authors":"Chundong Shi , Wen Nie , Guowei Ma , Jiangyong Sun , Junlin Wang , Li Wang","doi":"10.1016/j.ijrmms.2024.105944","DOIUrl":"10.1016/j.ijrmms.2024.105944","url":null,"abstract":"<div><div>Rock fragmentation is a critical process for mineral extraction and for mitigating overstressed rock in geotechnical applications. In this study, 3D-printed concrete was used to simulate the stratified rock mass, and experimental and numerical methods were employed to investigate crack propagation under static expansive loadings in transversely isotropic rocks. Two types of cracks were observed in the experiments: P-type (a crack propagates primarily along the weak layer) and T-type (a crack propagates across the weak layers) cracks. The findings revealed that the orientation of layers significantly influenced the initiation and propagation of cracks, with P-type cracks commonly observed in simpler P-P mode fragmentations and more complex P-P-T modes emerging under higher expansive loadings. P-T-T modes were characterized by the simultaneous presence of the T-type crack after an initial P-type crack. The AE energy levels in the P-P-T and P-T-T modes were much higher than those in the P-P mode. 2D-DDA models were further built to understand the effects of the loading scales, layer angles, and locations of weak layers on the cracking sequences. The results provided detailed insights into stress evolutions and the impact of expansive loadings on crack initiation and propagation.</div></div>","PeriodicalId":54941,"journal":{"name":"International Journal of Rock Mechanics and Mining Sciences","volume":"183 ","pages":"Article 105944"},"PeriodicalIF":7.0,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142561347","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}

引用次数: 0

Multi-stage evolution of pore structure of microwave-treated sandstone: Insights from nuclear magnetic resonance 微波处理砂岩孔隙结构的多阶段演变：核磁共振的启示

IF 7 1区工程技术 Q1 ENGINEERING, GEOLOGICAL

International Journal of Rock Mechanics and Mining Sciences

Pub Date : 2024-11-01 DOI: 10.1016/j.ijrmms.2024.105952

Yao Zhang , Yanan Gao , Liyuan Yu

Microwave fracturing has great potential in improving the efficiency of hard rock breaking. However, the pore evolution, which can be regarded as the damage accumulation and progressive failure of the rock subjected to microwave irradiation, remains unclear. In this study, nuclear magnetic resonance (NMR) is employed to investigate the pore evolution and fracture mechanism of the sandstone under different microwave power levels. The results show that the pore evolution of the specimens, including distribution of pore size, the weight in volume of various-sized pore, and porosity, exhibits different changing trends under various microwave power levels. The pore evolution of the specimens under microwave irradiation can be categorized into four phases: overall pore expansion, localized pore closure in the internal region, micro-cracks propagation induced by thermal stress, and macro-cracking (or melting). Moreover, pore evolution also plays a crucial role in the decomposition and evaporation of bound water, particularly when the specimens experience fractures triggered by thermal stress induced by the microwave treatment (TSIMT). The employing of NMR imaging (NMRI) description also provides an auxiliary and effective illustration on the pore evolution of the specimens under microwave irradiation. Finally, the mechanism of microwave-assisted rock breaking under different power levels is comprehensively discussed based on the NMR results from a microscopic perspective. It is anticipated that the findings of this study can provide valuable insights for enhancing the efficiency of microwave-assisted rock breaking.

微波压裂在提高硬岩破碎效率方面具有巨大潜力。然而，被视为岩石在微波辐照下损伤积累和逐渐破坏的孔隙演化仍不清楚。本研究采用核磁共振（NMR）技术研究了不同微波功率水平下砂岩的孔隙演化和断裂机制。结果表明，在不同的微波功率水平下，试样的孔隙演化，包括孔隙大小分布、各种大小孔隙的体积重量和孔隙率，呈现出不同的变化趋势。微波辐照下试样的孔隙演变可分为四个阶段：整体孔隙扩张、内部区域局部孔隙封闭、热应力引起的微裂纹扩展以及宏观裂纹（或熔化）。此外，孔隙演化在结合水的分解和蒸发中也起着至关重要的作用，尤其是当微波处理（TSIMT）引起的热应力导致试样断裂时。采用核磁共振成像（NMRI）描述也为微波辐照下试样的孔隙演变提供了有效的辅助说明。最后，基于核磁共振结果，从微观角度全面讨论了不同功率水平下微波辅助破岩的机理。预计本研究的结果可为提高微波辅助破岩效率提供有价值的见解。

{"title":"Multi-stage evolution of pore structure of microwave-treated sandstone: Insights from nuclear magnetic resonance","authors":"Yao Zhang , Yanan Gao , Liyuan Yu","doi":"10.1016/j.ijrmms.2024.105952","DOIUrl":"10.1016/j.ijrmms.2024.105952","url":null,"abstract":"<div><div>Microwave fracturing has great potential in improving the efficiency of hard rock breaking. However, the pore evolution, which can be regarded as the damage accumulation and progressive failure of the rock subjected to microwave irradiation, remains unclear. In this study, nuclear magnetic resonance (NMR) is employed to investigate the pore evolution and fracture mechanism of the sandstone under different microwave power levels. The results show that the pore evolution of the specimens, including distribution of pore size, the weight in volume of various-sized pore, and porosity, exhibits different changing trends under various microwave power levels. The pore evolution of the specimens under microwave irradiation can be categorized into four phases: overall pore expansion, localized pore closure in the internal region, micro-cracks propagation induced by thermal stress, and macro-cracking (or melting). Moreover, pore evolution also plays a crucial role in the decomposition and evaporation of bound water, particularly when the specimens experience fractures triggered by thermal stress induced by the microwave treatment (TSIMT). The employing of NMR imaging (NMRI) description also provides an auxiliary and effective illustration on the pore evolution of the specimens under microwave irradiation. Finally, the mechanism of microwave-assisted rock breaking under different power levels is comprehensively discussed based on the NMR results from a microscopic perspective. It is anticipated that the findings of this study can provide valuable insights for enhancing the efficiency of microwave-assisted rock breaking.</div></div>","PeriodicalId":54941,"journal":{"name":"International Journal of Rock Mechanics and Mining Sciences","volume":"183 ","pages":"Article 105952"},"PeriodicalIF":7.0,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142573463","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}

引用次数: 0

Monitoring stress-induced brittle rock mass damage for preventative support maintenance 监测应力诱发的脆性岩体破坏，进行预防性支持维护

IF 7 1区工程技术 Q1 ENGINEERING, GEOLOGICAL

International Journal of Rock Mechanics and Mining Sciences

Pub Date : 2024-11-01 DOI: 10.1016/j.ijrmms.2024.105927

Robert McMillan , Erik Eberhardt , Ryan Campbell , Avesiena Primadiansyah

Stress-induced brittle fracturing near an excavation boundary results in a volume increase, known as bulking. Excessive bulking places added demand on the rock support, which, if not detected and addressed through preventative support maintenance (i.e., proactively added reinforcement), can cause the support to fail, leading to a safety hazard and costly production delays for underground mining operations. For caving mines, these project risks are exacerbated during cave establishment due to the large abutment stress from undercutting that redistributes and concentrates stresses near excavations critical for production. This paper reports the findings from research conducted to develop and improve geotechnical monitoring practices to support preventative support maintenance in deep mining operations. This research uses a unique geotechnical monitoring database collected for the Deep Mill Level Zone panel cave mine. The data was collected across a large footprint during the mine's ramp-up period and represents an initial step toward best practices for data collection at cave mines operating in high-stress environments. Borehole camera surveys supplemented by multi-point borehole extensometers have been used to determine the depth of stress fracturing in pillar walls as a function of the distance away from the undercut. Convergence measurements and LiDAR scanning are used to characterize the corresponding rock mass bulking. The results show that the interpretation of monitoring data can be used to identify the long-term depth of stress fracturing and bulking trends in response to undercut advances. These show that direct measures of stress-induced fracturing damage provide an early indication of excavations vulnerable to bulking and that LiDAR scanning is an effective method for capturing the onset of bulking and anticipating local areas likely to experience greater deformation demand as bulking progresses. Proactive and strategic geotechnical monitoring based on the long-term depth of stress-induced fracturing trends is proposed to assist with preventative support maintenance practices.

挖掘边界附近应力引起的脆性断裂会导致体积增大，即所谓的隆起。过度膨胀会增加对岩石支护的需求，如果不通过预防性支护维护（即主动增加加固措施）来检测和解决，就会导致支护失效，给地下采矿作业带来安全隐患和代价高昂的生产延误。对于洞采矿山而言，由于下切产生的巨大支护应力会重新分布并集中在对生产至关重要的挖掘区附近，因此这些项目风险在建洞期间会进一步加剧。本文报告了为支持深部采矿作业中的预防性支护维护而开发和改进岩土工程监测方法的研究结果。这项研究使用了为深部磨矿水平区面板洞矿收集的独特岩土工程监测数据库。这些数据是在矿山提升期间在大范围内收集的，代表了在高压力环境下运营的洞穴矿山向数据收集最佳实践迈出的第一步。钻孔摄像勘测辅以多点钻孔延伸仪，用于确定支柱壁应力断裂深度与下切距离的函数关系。汇聚测量和激光雷达扫描用于确定相应岩体隆起的特征。结果表明，通过对监测数据的解释，可以确定应力断裂的长期深度以及下切推进时的隆起趋势。这些结果表明，对应力引起的断裂破坏进行直接测量，可及早发现易受隆起影响的开挖点，而激光雷达扫描则是捕捉隆起开始和预测随着隆起的推进可能出现更大变形需求的局部区域的有效方法。建议根据应力诱发断裂的长期深度趋势进行积极主动的战略性岩土工程监测，以协助开展预防性支持维护工作。

{"title":"Monitoring stress-induced brittle rock mass damage for preventative support maintenance","authors":"Robert McMillan , Erik Eberhardt , Ryan Campbell , Avesiena Primadiansyah","doi":"10.1016/j.ijrmms.2024.105927","DOIUrl":"10.1016/j.ijrmms.2024.105927","url":null,"abstract":"<div><div>Stress-induced brittle fracturing near an excavation boundary results in a volume increase, known as bulking. Excessive bulking places added demand on the rock support, which, if not detected and addressed through preventative support maintenance (i.e., proactively added reinforcement), can cause the support to fail, leading to a safety hazard and costly production delays for underground mining operations. For caving mines, these project risks are exacerbated during cave establishment due to the large abutment stress from undercutting that redistributes and concentrates stresses near excavations critical for production. This paper reports the findings from research conducted to develop and improve geotechnical monitoring practices to support preventative support maintenance in deep mining operations. This research uses a unique geotechnical monitoring database collected for the Deep Mill Level Zone panel cave mine. The data was collected across a large footprint during the mine's ramp-up period and represents an initial step toward best practices for data collection at cave mines operating in high-stress environments. Borehole camera surveys supplemented by multi-point borehole extensometers have been used to determine the depth of stress fracturing in pillar walls as a function of the distance away from the undercut. Convergence measurements and LiDAR scanning are used to characterize the corresponding rock mass bulking. The results show that the interpretation of monitoring data can be used to identify the long-term depth of stress fracturing and bulking trends in response to undercut advances. These show that direct measures of stress-induced fracturing damage provide an early indication of excavations vulnerable to bulking and that LiDAR scanning is an effective method for capturing the onset of bulking and anticipating local areas likely to experience greater deformation demand as bulking progresses. Proactive and strategic geotechnical monitoring based on the long-term depth of stress-induced fracturing trends is proposed to assist with preventative support maintenance practices.</div></div>","PeriodicalId":54941,"journal":{"name":"International Journal of Rock Mechanics and Mining Sciences","volume":"183 ","pages":"Article 105927"},"PeriodicalIF":7.0,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142552488","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}

引用次数: 0

Modeling of thermally driven longitudinal fractures along a vertical well 垂直井热驱动纵向裂缝建模

IF 7 1区工程技术 Q1 ENGINEERING, GEOLOGICAL

International Journal of Rock Mechanics and Mining Sciences

Pub Date : 2024-10-29 DOI: 10.1016/j.ijrmms.2024.105942

Bin Chen , Quanlin Zhou

Fluid injection via a vertical well into a high-temperature formation may induce multiple longitudinal thermal fractures, which may eventually transition to two-wing fractures during fracture propagation, depending on horizontal stress ratio

κ

. In this study, we develop a plane strain model with radial heat conduction to investigate either two-wing fractures under highly anisotropic stresses

κ_{h a} ≫ 1

or multiple fractures under isotropic stresses

κ = 1

. The coupled dimensionless elasticity equation and criteria of fracture propagation (and arrest) are formulated, discretized, and solved iteratively (with two special algorithms). Two additional critical model parameters are dimensionless effective confining stress

T

and wellbore radius

A

. The multiple-fracture solution of dimensionless fracture length

L

, angular spacing

D

, 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

τ

, as verified numerically. The late-time fracture propagation follows scaling law

L = f (T, A, D) τ^{(1 - 2 T) / 2}

. These solutions and scaling laws can be used to well bound a general solution with

1 < κ < κ_{h a}

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.

通过垂直井向高温地层注入流体可能会诱发多条纵向热裂缝，在裂缝扩展过程中，根据水平应力比κ的不同，这些裂缝最终可能会转变为两翼裂缝。在本研究中，我们建立了一个具有径向热传导的平面应变模型，以研究高度各向异性应力κha≫1条件下的两翼断裂或各向同性应力κ=1条件下的多重断裂。对耦合的无量纲弹性方程和断裂扩展（和闭合）准则进行了表述、离散化和迭代求解（采用两种特殊算法）。另外两个关键的模型参数是无量纲有效约束应力 T 和井筒半径 A。无量纲裂缝长度 L、角间距 D 和孔径的多重裂缝解法包括在近井筒区域裂缝的竞争性传播和阻滞解法，以及随后远离井筒的裂缝稳定传播解法。经数值验证，多裂缝和双翼裂缝解决方案都准确捕捉到了无量纲时间τ的早期瞬态和晚期幂律变化。晚期断裂扩展遵循缩放定律 L=fT,A,Dτ1-2T/2。这些解法和缩放定律可以很好地约束一般解法，即 1<κ<κha，这在一个地热场地得到了数值验证，在冷却 1 天、100 天和 10,000 天后，最大断裂长度分别达到 0.45 米、2.71 米和 16.42 米。讨论了理论和数值分析中所用假设的适用性。

{"title":"Modeling of thermally driven longitudinal fractures along a vertical well","authors":"Bin Chen , 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><</mo><mi>κ</mi><mo><</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}

引用次数: 0

An elastoplastic solution for lined hydrogen storage caverns during excavation and operation phases considering strain softening and dilatancy 考虑到应变软化和扩张的内衬储氢洞在挖掘和运行阶段的弹塑性解决方案

IF 7 1区工程技术 Q1 ENGINEERING, GEOLOGICAL

International Journal of Rock Mechanics and Mining Sciences

Pub Date : 2024-10-29 DOI: 10.1016/j.ijrmms.2024.105949

Kai Qiu , Shuchen Li , Zhongzhong Liu , Meng Yuan , Shisen Zhao , Zeen Wan

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 (R_s) and plastic residual zone (R_r) were analyzed. Results show that higher surrounding rock quality can effectively reduce both R_s and R_r. Nevertheless, when the surrounding rock quality already reaches a high standard, such as c₁ > 3.5 MPa, φ₁ > 65°, or E > 55 MPa, it becomes inefficient to overly pursue further improvements in the surrounding rock quality. Furthermore, the strain softening and dilatancy phenomena only affect R_r. Additionally, the concrete lining with higher stiffness can share a larger portion of the hydrogen pressure, thus reducing both R_s and R_r. Notably, When the elastic modulus of concrete increases from 20 MPa to 40 MPa, R_r decreases by 31.98 % and R_s decreases by 20.96 %. Moreover, the critical hydrogen pressure (P_Hcr) at which the surrounding rock begins to enter a plastic state is proportional to the ground stress (P₀). Specifically, when P₀ is increased sequentially from 2.5 MPa to 3.0 MPa and 3.5 MPa, P_Hcr 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.

内衬岩洞（LRCs）中的地下氢能储存（UHES）是解决清洁能源发电不稳定和不均匀难题的重要方法。然而，要实现更高的储氢效率，往往需要利用更高的储氢压力。因此，全面了解氢压下围岩的弹塑性机械响应对于确保超高压储氢系统的安全性至关重要。本研究建立了 LRC 在施工和运行阶段的弹塑性解决方案。影响围岩峰值后机械响应的两个基本现象--应变软化和膨胀--被耦合到塑性解决方案中。开发了一种计算程序，并通过与数值模型的比较验证了其准确性。分析了围岩质量参数、应变软化和膨胀参数、混凝土质量参数和氢压力对塑性软化区（Rs）和塑性残余区（Rr）半径的影响。结果表明，围岩质量越高，Rs 和 Rr 越小。然而，当围岩质量已经达到较高标准时，如 c1 > 3.5 MPa、φ1 > 65° 或 E > 55 MPa，过分追求围岩质量的进一步提高就会变得效率低下。此外，应变软化和膨胀现象只影响 Rr。此外，刚度较高的混凝土衬砌可以分担较大部分的氢压力，从而降低 Rs 和 Rr。值得注意的是，当混凝土的弹性模量从 20 兆帕增加到 40 兆帕时，Rr 减少了 31.98%，Rs 减少了 20.96%。此外，围岩开始进入塑性状态的临界氢压力 (PHcr) 与地应力 (P0) 成正比。具体来说，当 P0 从 2.5 兆帕依次增加到 3.0 兆帕和 3.5 兆帕时，PHcr 依次变为 2.4 兆帕、4.0 兆帕和 5.0 兆帕。本研究的结果有助于提高喇嘛研究中心在施工和运行期间的安全性。

{"title":"An elastoplastic solution for lined hydrogen storage caverns during excavation and operation phases considering strain softening and dilatancy","authors":"Kai Qiu , Shuchen Li , Zhongzhong Liu , Meng Yuan , Shisen Zhao , 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><sub><em>s</em></sub>) and plastic residual zone (<em>R</em><sub><em>r</em></sub>) were analyzed. Results show that higher surrounding rock quality can effectively reduce both <em>R</em><sub><em>s</em></sub> and <em>R</em><sub><em>r</em></sub>. Nevertheless, when the surrounding rock quality already reaches a high standard, such as <em>c</em><sub>1</sub> > 3.5 MPa, <em>φ</em><sub>1</sub> > 65°, or <em>E</em> > 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><sub><em>r</em></sub>. Additionally, the concrete lining with higher stiffness can share a larger portion of the hydrogen pressure, thus reducing both <em>R</em><sub><em>s</em></sub> and <em>R</em><sub><em>r</em></sub>. Notably, When the elastic modulus of concrete increases from 20 MPa to 40 MPa, <em>R</em><sub><em>r</em></sub> decreases by 31.98 % and <em>R</em><sub><em>s</em></sub> decreases by 20.96 %. Moreover, the critical hydrogen pressure (<em>P</em><sub><em>Hcr</em></sub>) at which the surrounding rock begins to enter a plastic state is proportional to the ground stress (<em>P</em><sub>0</sub>). Specifically, when <em>P</em><sub>0</sub> is increased sequentially from 2.5 MPa to 3.0 MPa and 3.5 MPa, <em>P</em><sub><em>Hcr</em></sub> 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}

引用次数: 0

A fault activation-shearing-sliding peridynamic model exploring the role of static and kinetic frictional contacts 探索静态和动态摩擦接触作用的断层激活-剪切-滑动周向动力学模型

IF 7 1区工程技术 Q1 ENGINEERING, GEOLOGICAL

International Journal of Rock Mechanics and Mining Sciences

Pub Date : 2024-10-28 DOI: 10.1016/j.ijrmms.2024.105946

Zhen Yang , HanYi Wang , Mukul Sharma , Erdogan Madenci

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.

了解断层动力学对于理解地震事件的基本机制至关重要。本研究在周动力（PD）框架内引入了一种新的断层激活-剪切-滑动模型，该模型以定义明确的静摩擦和动摩擦行为为特征。静摩擦键的作用是维持垂直于断层平面的法向力，并管理沿断层几何形状的切向摩擦力。这些粘结的失效与断层激活直接相关，而随后的滑动阶段则由短程动摩擦模型控制。此外，还提出了一种自适应识别方法，用于精确确定任意形状接触面上的局部单位法向量。通过故障激活和板滑动摩擦试验，验证了模型的有效性和适用性。该模型还进一步用于研究局部几何形状、粗糙度和摩擦系数对故障行为的影响，并与实验结果进行比较。观察结果表明，影响断层抗剪能力的主要因素在不同阶段各不相同，主要涉及激活过程中的静摩擦、剪切过程中的压实变形和滑动过程中的动摩擦。当抗剪性主要受摩擦力支配时，它对各种剪切力（包括间接加载扰动产生的剪切力）表现出更高的敏感性。

{"title":"A fault activation-shearing-sliding peridynamic model exploring the role of static and kinetic frictional contacts","authors":"Zhen Yang , HanYi Wang , Mukul Sharma , 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}

引用次数: 0

Geothermal fluid extraction and injection-related fracture slip susceptibility and seismicity in naturally fractured rocks 与地热流体抽取和注入有关的天然裂隙岩断裂滑移易感性和地震性

IF 7 1区工程技术 Q1 ENGINEERING, GEOLOGICAL

International Journal of Rock Mechanics and Mining Sciences

Pub Date : 2024-10-28 DOI: 10.1016/j.ijrmms.2024.105939

Wenzhuo Cao , Sevket Durucan , Ji-Quan Shi , Anna Korre , Thomas Ratouis , Vala Hjörleifsdóttir

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.

了解地热储层中的断裂滑移易感性是控制流体注入诱发地震的核心。为了研究区域断裂系统对诱发地震的作用，开发了一个包含断裂网络的热-水-机械（THM）耦合模型，该模型的特点是显性断裂、断裂岩石（具有小尺度断裂的多孔基质块）及其相互作用的不同物理特性之间的直接耦合，以及通过材料特性变化（如应力相关断裂和岩石渗透率）的间接耦合。该模型利用现场记录的月生产量和再注入率，模拟了十年期间（2011-2021 年）Hellisheiði 地热田由三个主要断裂组组成的天然断裂系统中的地热流体抽取和再注入情况。根据模型结果，研究了在不同时间尺度（即短期（1 个月）、中期（1 年）和长期（10 年））的流体再注入开始前后的储层条件下，区域断裂系统的滑动敏感性。为了研究冷却收缩和流体超压对裂缝滑移敏感性的相对影响，考虑了两种模型方案，一种是有冷却收缩的方案，另一种是没有冷却收缩的方案。结果表明，断裂网络是流体流动的优先通道，影响着地热储层中的流体压力和应力分布以及断裂滑移易感性。在开始重新注入流体之前，Hellisheiði 的东北-西南和北-南走向断裂容易发生滑移。在流体再注入过程中，滑移易感性增强的断裂分布逐渐从再注入区域周围转移到再注入区域周围的断层法线方向上，形成两叶状，这表明在中期和长期内，冷却收缩对断裂滑移易感性的影响要大于流体超压。

{"title":"Geothermal fluid extraction and injection-related fracture slip susceptibility and seismicity in naturally fractured rocks","authors":"Wenzhuo Cao , Sevket Durucan , Ji-Quan Shi , Anna Korre , Thomas Ratouis , 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}

引用次数: 0

3D in-situ stress prediction for shale reservoirs based on the CapsNet-BiLSTM hybrid model 基于 CapsNet-BiLSTM 混合模型的页岩储层三维原位应力预测

IF 7 1区工程技术 Q1 ENGINEERING, GEOLOGICAL

International Journal of Rock Mechanics and Mining Sciences

Pub Date : 2024-10-28 DOI: 10.1016/j.ijrmms.2024.105937

Fen Lyu , Junping Liu , Li Chen , Bocheng Tao , Xingye Liu

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.

原位应力对页岩储层压裂、油气迁移以及井筒稳定性和钻井优化至关重要。三维原位应力的准确预测与地震数据密不可分。然而，现有方法主要依赖于经验公式或简化假设，这限制了其在表示原位应力真实分布方面的准确性。此外，这些方法往往从单一因素预测原位应力，导致高度不确定性。为了解决这些问题，我们提出了一种利用胶囊网络-双向长短期记忆（CapsNet-BiLSTM）混合模型预测三维原位应力的方法。该方法考虑了地质特征和地震属性等各种因素，以实现更准确的预测。首先，我们分析了页岩层的结构特征，并利用岩石岩石物理知识合理过滤输入数据，消除了冗余参数对原位应力预测的影响。然后，为了克服传统深度学习模型在捕捉复杂数据结构中相关性方面的局限性，我们构建了一个 CapsNet-BiLSTM 网络模型。该模型集成了 CapsNet 的空间关系建模能力和 BiLSTM 的时间建模能力，更好地考虑了页岩储层的各向异性特征和时序信息。将该方法应用于四川盆地的一个研究区域表明，所构建的CapsNet-BiLSTM混合模型能够准确预测原位应力值，有效捕捉页岩储层内复杂原位应力的空间分布模式，从而证明了我们的方法在页岩油气藏地质工程应用中的有效性和潜力。这种基于混合模型的预测方法不仅提高了原位应力预测的准确性，而且为相关领域的科学研究和工程实践提供了宝贵的方法和技术支持。

{"title":"3D in-situ stress prediction for shale reservoirs based on the CapsNet-BiLSTM hybrid model","authors":"Fen Lyu , Junping Liu , Li Chen , Bocheng Tao , 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}

引用次数: 0

The role of annealing and grain boundary controls on the mechanical properties of limestones and marbles 退火和晶界控制对灰岩和大理石机械特性的作用

IF 7 1区工程技术 Q1 ENGINEERING, GEOLOGICAL

International Journal of Rock Mechanics and Mining Sciences

Pub Date : 2024-10-28 DOI: 10.1016/j.ijrmms.2024.105926

Rui Zhang , Paul A. Bosomworth , Juliane Weber , Jan Ilavsky , Si Athena Chen , Alexis Flores-Betancourt , Elliot Paul Gilbert , Jitendra Mata , Mark L. Rivers , Peter J. Eng , Lawrence M. Anovitz

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.

在许多地质和地球化学环境中，化学和机械过程是相互关联的。反应过程会使缺陷退火并重组晶界，从而改变其弹性特性、内摩擦力水平、波传播速度和断裂行为。然而，这些变化的性质取决于岩石的初始状态。在这项研究中，我们使用脉冲激励来测量三种碳酸盐岩在 300 °C 下的机械特性变化与干燥和蒸汽加热时间的函数关系：卡拉拉大理石、迦太基大理石（伯灵顿石灰岩）和德克萨斯奶油石灰岩（爱德华兹石灰岩）的初始孔隙率分别约为 1%、3% 和 27%。观察到频率相关现象以及矿物再结晶。结合小角 X 射线和中子散射分析，确定了块体机械性能和微观结构性能变化之间的关系。观察到实验石灰岩的杨氏模量和剪切模量都随加热时间而降低，这反映并量化了退火导致的岩石刚度降低。随着反应时间的延长，样品的内摩擦力先增大后减小，这反映了缺陷退火，但这又与晶界溶解相平衡，显然是由于蒸汽在封闭的晶界环境中凝结造成的。这表明，在密闭条件下，沸点升高会导致溶解、孔隙率增加和晶界扩大。此外，对小角 X 射线和中子散射结果的比较表明，在对典型的小角散射样品进行定量分析时，假设孔隙是空的是不恰当的。

{"title":"The role of annealing and grain boundary controls on the mechanical properties of limestones and marbles","authors":"Rui Zhang , Paul A. Bosomworth , Juliane Weber , Jan Ilavsky , Si Athena Chen , Alexis Flores-Betancourt , Elliot Paul Gilbert , Jitendra Mata , Mark L. Rivers , Peter J. Eng , 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}

引用次数: 0