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Fracture characterization of fractured rock bodies based on acoustic and optical characteristics 基于声学和光学特征的断裂岩体断裂特征描述
IF 2.9 3区 地球科学 Q3 GEOSCIENCES, MULTIDISCIPLINARY Pub Date : 2024-08-28 DOI: 10.3389/feart.2024.1421355
Jiyong Zhang, Qianjin Zou, Huadong Guan
Crack propagation is an important cause of damage to rock bodies. In this study, uniaxial compression tests were conducted on specimens with rock-like mass containing fissures with different inclination angles to study the effect of crack angle on the crack evolution and fracture characteristics of rock bodies. The specimen surface deformation and internal response characteristics during fracture were analyzed via digital image correlation (DIC) and acoustic emission (AE) techniques. The results indicated that the AE characteristics of the fractured specimens exhibited a high degree of activity during the pore compaction and crack propagation stages. The prefabricated fissure configuration affected the stress state at the fissure tip, leading to differences in the crack evolution paths and rupture modes of fissure specimens with different angles. Under the uniaxial peak intensity, the relative position of the normalized global strain curve peak point gradually shifted from the specimen tip to the middle of the specimen as the crack angle increased, which corresponded to the shear damage-tension-shear mixed damage-tension damage modes of the specimen. The findings of this study indicate that normalized global strain curves can reflect the characteristics of crack evolution and provide a basis for the discrimination of fissured rock mass damage modes.
裂纹扩展是造成岩体破坏的重要原因。本研究对含有不同倾角裂缝的类岩体试样进行了单轴压缩试验,以研究裂缝角度对岩体裂缝演化和断裂特征的影响。通过数字图像相关(DIC)和声发射(AE)技术分析了断裂过程中试样的表面变形和内部响应特性。结果表明,在孔隙压实和裂缝扩展阶段,断裂试样的声发射特征表现出高度的活跃性。预制裂缝构造影响了裂缝顶端的应力状态,导致不同角度裂缝试样的裂缝演变路径和破裂模式存在差异。在单轴峰值强度下,随着裂纹角度的增大,归一化全局应变曲线峰值点的相对位置逐渐从试样顶端转移到试样中部,对应于试样的剪切破坏-拉伸破坏-剪切混合破坏-拉伸破坏模式。研究结果表明,归一化全局应变曲线可以反映裂缝演变的特征,为裂隙岩体破坏模式的判别提供依据。
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引用次数: 0
Frontiers | Construction and application of multi-scale costal bedrock urban 3D engineering geological models in Qingdao City of China 前沿 | 中国青岛市多尺度造价基岩城市三维工程地质模型的构建与应用
IF 2.9 3区 地球科学 Q3 GEOSCIENCES, MULTIDISCIPLINARY Pub Date : 2024-08-28 DOI: 10.3389/feart.2024.1435824
Dong Ji, Jing Hou, Zhiliang Cheng, Shuai Wei, Yue Zhai, Wenhao Li
The 3D geological model serves as a cornerstone, establishing the essential foundation and prerequisite for numerical simulations, analytical assessments, and evaluative procedures that are integral to the disciplines of geotechnical and geological engineering. The task of integrating vast quantities of multi-source, heterogeneous modeling data, the absence of stratigraphic division standards to meet varying precision requirements, and addressing the application demands of 3D geological models beyond the geological domain, pose significant challenges to the endeavor of 3D geological modeling. This is especially true for the construction of large-scale, high-precision 3D geological models at the urban level. Our research introduces a methodology for 3D geological modelling, with a particular focus on the dual-weighted interpolation technique for the integration of land-sea data and the establishment of a three-tiered coding system for bedrock layers. Focusing on Qingdao, a city characterized by its bedrock geology and situated along the eastern coastal region of China, our proposed method has successfully catalyzed the creation of models across four distinct scales: a comprehensive city-wide model covering an area of 11,282 square kilometers, five general models, two demonstration models, and five refined models. Further application cases have demonstrated that these models are not only capable of meeting the requirements of geological and geotechnical engineering across various scenarios, but also exhibit excellent interoperability and significant application potential when integrated with Building Information Modeling (BIM), Geographic Information Systems (GIS), and Internet of Things (IoT) technologies. The outcomes of this study are significant for the theoretical development and technological advancement of 3D geological modeling, and can also bring inspiration and reference to the work of 3D geological modeling in other areas.
三维地质模型是岩土工程和地质工程学科不可或缺的基石,为数值模拟、分析评估和评价程序奠定了重要的基础和前提。整合大量多源、异构建模数据的任务,缺乏满足不同精度要求的地层划分标准,以及解决三维地质模型在地质领域之外的应用需求,都给三维地质建模工作带来了巨大挑战。这对于在城市层面构建大规模、高精度的三维地质模型来说尤为如此。我们的研究介绍了一种三维地质建模方法,尤其侧重于海陆数据整合的双加权插值技术,以及基岩层三级编码系统的建立。以中国东部沿海地区以基岩地质为特征的城市青岛为重点,我们提出的方法成功地催生了四个不同尺度的模型:一个覆盖面积为 11,282 平方公里的全市综合模型、五个一般模型、两个示范模型和五个精细模型。进一步的应用案例表明,这些模型不仅能够满足地质和岩土工程在各种情况下的要求,而且在与建筑信息模型 (BIM)、地理信息系统 (GIS) 和物联网 (IoT) 技术集成后,还表现出卓越的互操作性和巨大的应用潜力。本研究的成果对三维地质建模的理论发展和技术进步具有重要意义,也可为其他领域的三维地质建模工作带来启发和借鉴。
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引用次数: 0
Frontiers | .1.1 Late Holocene hydrologic variability and ecosystem structure from rock hyrax middens in Dhofar, Oman 前沿 | .1.1 从阿曼佐法尔(Dhofar)的岩鬣狗穴看全新世晚期的水文变异性和生态系统结构
IF 2.9 3区 地球科学 Q3 GEOSCIENCES, MULTIDISCIPLINARY Pub Date : 2024-08-28 DOI: 10.3389/feart.2024.1441323
Kaitlyn E. Horisk, Sarah Ivory, Katherine Freeman, Allison Baczynski, Joy McCorriston, Andrew Anderson, R Scott Anderson, Ali Al Kathiri
Over 1/3 of the Earth’s human population relies on dryland ecosystems for food and water resources. While these ecosystems are highly sensitive to changes in climate, we lack observational data as to how changes in hydrology influences plant communities. Paleoecological data for southern Arabia show woodland communities transitioned to more dry-adapted herbaceous plants, which suggests rainfall decreased across the Holocene. To assess relationships between hydrology and ecology, we employed leaf wax n-alkane distributions, δ13Cwax, and δDwax records from rock hyrax (Procavia capensis) middens in Dhofar, Oman. The biomarker properties allowed reconstruction of changes in C3/C4 vegetation and local moisture availability, in tandem with community changes represented by a published pollen record. To constrain interpretations, n-alkane analyses were conducted on herbarium specimens of leaves collected in Dhofar. For the modern specimens, xeric plants typically contained longer homologues than mesic plants. Across the fossil middens (4,038–109 cal yrs BP), the proportions of plant-wax homologues do not show major changes, and thus do not suggest a shift between xeric versus mesic plants. Similarly, δ13Cwax values indicate little or no change in the distributions of C3 and C4 vegetation. Limited δDwax data from the middens confirm overall drying occurred into the late Holocene, punctuated by a wetter pulse at ∼1.6 ka. Taken together, plant wax distributions and isotope data indicate changes in moisture availability across the late Holocene did not alter the structural composition of the plant communities and that the proportion of C3/C4 vegetation remained stable. We infer vegetation changes associated with late Holocene drying involved reshuffling of community composition and not major changes in vegetation structure. Additionally, this study demonstrates that leaf wax n-alkanes from rock hyrax middens provide a method to reconstruct changes in climate and vegetation in dryland ecosystems where other archives are scarce.
地球上超过三分之一的人类依靠旱地生态系统获取食物和水资源。虽然这些生态系统对气候变化高度敏感,但我们缺乏水文变化如何影响植物群落的观测数据。阿拉伯南部的古生态学数据显示,林地群落过渡到更多适应干旱的草本植物,这表明整个全新世降雨量减少。为了评估水文与生态之间的关系,我们采用了来自阿曼佐法尔岩鬣蜥(Procavia capensis)穴居的叶蜡正构烷烃分布、δ13Cwax 和 δDwax记录。生物标志物的特性有助于重建 C3/C4 植被和当地水分供应的变化,以及已发表的花粉记录所代表的群落变化。为了限制解释,对在佐法尔采集的标本馆树叶标本进行了正烷烃分析。在现代标本中,干旱植物的同源物通常比中生植物的同源物长。在整个化石群(公元前 4,038-109 年)中,植物蜡同源物的比例没有发生重大变化,因此并不表明干旱植物与中生植物之间发生了转变。同样,δ13C 蜡值表明 C3 和 C4 植被的分布几乎没有变化。地层中有限的 δDwax 数据证实了全新世晚期的整体干燥,在 ∼1.6 ka 出现了一次较湿润的脉冲。综合来看,植物蜡的分布和同位素数据表明,整个全新世晚期水分供应的变化并没有改变植物群落的结构组成,C3/C4植被的比例保持稳定。我们推断,与全新世晚期干旱有关的植被变化涉及群落组成的重新组合,而不是植被结构的重大变化。此外,这项研究还表明,岩鬣蜥巢穴中的叶蜡正构烷烃为重建气候和植被的变化提供了一种方法,而在干旱地区的生态系统中,其他档案资料十分匮乏。
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引用次数: 0
Frontiers | Comprehensive study on the stability and failure mechanism of landslides under rainfall and earthquake in northwest mountainous areas 前沿 | 西北山区降雨和地震作用下滑坡稳定性和破坏机理的综合研究
IF 2.9 3区 地球科学 Q3 GEOSCIENCES, MULTIDISCIPLINARY Pub Date : 2024-08-27 DOI: 10.3389/feart.2024.1470083
Weixin Yang, Yonggang Zhang, Lei Zhang, Gexue Bai, Baofeng Wan, Ning An
Landslides and geological disasters occur frequently in the mountainous areas of northwest China, seriously threatening people’s life and property of the region. In this study, we investigated the Lijie Beishan landslide as a typical case and combines the results of on-site geological surveys to conduct two-dimensional and three-dimensional numerical simulations of the landslide, evaluating its stability under self-weight, rainfall, and earthquake action. By analyzing the generalized shear strain, displacement, and stability coefficient of the landslide, it is determined that the stability of the landslide shows a decreasing trend under static, rainfall, and earthquake conditions. Landslides exhibit tension controlled failure modes under normal static and rainfall conditions, and translational failure modes under earthquake conditions. Compared with static and rainfall conditions, landslides have the largest volume and sliding distance under earthquake conditions. By combining the transfer coefficient method and the simplified Bishop method, a comparative analysis was conducted on the stability of the landslide. It was found that the stability coefficients under different working conditions were consistent with the simulation results, which verified the reliability of the simulation results. The research results of this paper will assist in clarifying the development mechanism of this type of landslides and provide valuable references for the stability evaluation of landslides in the northwest mountainous areas.
中国西北山区滑坡地质灾害频发,严重威胁着当地人民的生命财产安全。本研究以丽江北山滑坡为典型案例,结合现场地质勘察成果,对滑坡进行了二维和三维数值模拟,评价了滑坡在自重、降雨和地震作用下的稳定性。通过分析滑坡的广义剪切应变、位移和稳定系数,确定滑坡在静态、降雨和地震条件下的稳定性呈下降趋势。滑坡在正常静力和降雨条件下表现出拉力控制破坏模式,在地震条件下表现出平移破坏模式。与静力和降雨条件相比,地震条件下滑坡的体积和滑动距离最大。结合传递系数法和简化 Bishop 法,对滑坡的稳定性进行了对比分析。结果发现,不同工况下的稳定系数与模拟结果一致,验证了模拟结果的可靠性。本文的研究成果将有助于阐明该类滑坡的发展机理,为西北山区滑坡的稳定性评价提供有价值的参考。
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引用次数: 0
Investigating the internal erosion behavior and microscopic mechanisms of chemically stabilized soil: an experimental study 调查化学稳定土壤的内部侵蚀行为和微观机制:一项实验研究
IF 2.9 3区 地球科学 Q3 GEOSCIENCES, MULTIDISCIPLINARY Pub Date : 2024-08-27 DOI: 10.3389/feart.2024.1452449
Buping Zhang, Xinghua Zhu, Xuewen Tao, Mengkui Wang, Aamir Asghar, Guoliang Mi
IntroductionInternal erosion triggered by water pipeline leaks seriously threatens the stability of the urban ground. Hangzhou, a city in Zhejiang Province, China, is facing critical challenges due to urban ground collapse (UGC) caused by internal erosion. However, there is a lack of research on the prevention of UGC by improving the internal erodibility of underground soil. Addressing this issue is of utmost importance to ensure the city’s stability and safety. This paper proposes to improve the internal erodibility of typical sandy silt soils with chemical stabilisers.MethodsThe effects of three chemical stabilisers, lignosulphonate (LS), lime (LI), and lignin fibre (LF), on the critical shear stress (τc) and erosion coefficient (kd) of sandy silt soils were investigated, which from Hangzhou, Zhejiang, China, by the hole erosion test (HET) at different mixing amounts and at different conservation times.ResultsThe findings indicate that LF mainly improves the erosion resistance of sandy silt by increasing τc, and the maximum increase is 2.38 times; LI mainly improves the erosion resistance by decreasing kd, and the maximum decrease is 2.18 times. After adding LS, τc and kd did not change significantly. The scanning electron microscope (SEM) test revealed that the inclusion of LF led to the formation of larger agglomerates in the sandy silt soil. The microstructure of sandy silt soil remained dispersed even after adding LS. Various chemical stabilisers used to improve sandy silt soils exhibited distinct erosion mechanisms. Sandy silt soils improved with LF exfoliated into agglomerates, displaying high resistance to erosion. On the other hand, the sandy silt treated with LF still lacks a protective layer and shows minimal improvements in its ability to withstand erosion. In contrast, the LS-amended sandy silt remains stripped with individual soil particles with insignificant changes in erosion resistance.DiscussionThis study can provide a conceptual framework for choosing foundation treatment techniques in future urban development projects.
导言输水管道泄漏引发的内侵蚀严重威胁着城市地面的稳定性。中国浙江省杭州市正面临着由内侵蚀引发的城市地面塌陷(UGC)的严峻挑战。然而,关于通过改善地下土壤内部侵蚀性来预防城市地面塌陷的研究却十分匮乏。解决这一问题对于确保城市的稳定和安全至关重要。方法通过孔侵蚀试验(HET)研究了木质素磺酸盐(LS)、石灰(LI)和木质素纤维(LF)这三种化学稳定剂在不同掺量和不同养护时间下对中国浙江杭州砂质粉土临界剪应力(τc)和侵蚀系数(kd)的影响。结果表明,LF 主要通过增加 τc 来提高砂质粉土的抗侵蚀性,最大增幅为 2.38 倍;LI 主要通过降低 kd 来提高抗侵蚀性,最大降幅为 2.18 倍。加入 LS 后,τc 和 kd 变化不大。扫描电子显微镜(SEM)测试显示,加入 LF 后,砂质粉土中形成了较大的团聚体。即使添加了 LS,砂质粉土的微观结构仍然很分散。用于改良砂质粉土的各种化学稳定剂表现出不同的侵蚀机制。用 LF 改良过的砂质粉土会剥落成团块,表现出很强的抗侵蚀能力。另一方面,用 LF 处理过的砂质粉土仍然缺乏保护层,抗侵蚀能力的改善微乎其微。与此相反,经 LS 改良的砂质粉土仍然是由单个土壤颗粒剥离而成,抗侵蚀能力变化不大。
{"title":"Investigating the internal erosion behavior and microscopic mechanisms of chemically stabilized soil: an experimental study","authors":"Buping Zhang, Xinghua Zhu, Xuewen Tao, Mengkui Wang, Aamir Asghar, Guoliang Mi","doi":"10.3389/feart.2024.1452449","DOIUrl":"https://doi.org/10.3389/feart.2024.1452449","url":null,"abstract":"IntroductionInternal erosion triggered by water pipeline leaks seriously threatens the stability of the urban ground. Hangzhou, a city in Zhejiang Province, China, is facing critical challenges due to urban ground collapse (UGC) caused by internal erosion. However, there is a lack of research on the prevention of UGC by improving the internal erodibility of underground soil. Addressing this issue is of utmost importance to ensure the city’s stability and safety. This paper proposes to improve the internal erodibility of typical sandy silt soils with chemical stabilisers.MethodsThe effects of three chemical stabilisers, lignosulphonate (LS), lime (LI), and lignin fibre (LF), on the critical shear stress (<jats:italic>τ</jats:italic><jats:sub>c</jats:sub>) and erosion coefficient (<jats:italic>k</jats:italic><jats:sub>d</jats:sub>) of sandy silt soils were investigated, which from Hangzhou, Zhejiang, China, by the hole erosion test (HET) at different mixing amounts and at different conservation times.ResultsThe findings indicate that LF mainly improves the erosion resistance of sandy silt by increasing <jats:italic>τ</jats:italic><jats:sub>c</jats:sub>, and the maximum increase is 2.38 times; LI mainly improves the erosion resistance by decreasing <jats:italic>k</jats:italic><jats:sub>d</jats:sub>, and the maximum decrease is 2.18 times. After adding LS, <jats:italic>τ</jats:italic><jats:sub>c</jats:sub> and <jats:italic>k</jats:italic><jats:sub>d</jats:sub> did not change significantly. The scanning electron microscope (SEM) test revealed that the inclusion of LF led to the formation of larger agglomerates in the sandy silt soil. The microstructure of sandy silt soil remained dispersed even after adding LS. Various chemical stabilisers used to improve sandy silt soils exhibited distinct erosion mechanisms. Sandy silt soils improved with LF exfoliated into agglomerates, displaying high resistance to erosion. On the other hand, the sandy silt treated with LF still lacks a protective layer and shows minimal improvements in its ability to withstand erosion. In contrast, the LS-amended sandy silt remains stripped with individual soil particles with insignificant changes in erosion resistance.DiscussionThis study can provide a conceptual framework for choosing foundation treatment techniques in future urban development projects.","PeriodicalId":12359,"journal":{"name":"Frontiers in Earth Science","volume":"61 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142179665","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Comprehensive database of land subsidence in 143 major coastal cities around the world: overview of issues, causes, and future challenges 全球 143 个主要沿海城市土地沉降综合数据库:问题、原因和未来挑战概述
IF 2.9 3区 地球科学 Q3 GEOSCIENCES, MULTIDISCIPLINARY Pub Date : 2024-08-27 DOI: 10.3389/feart.2024.1351581
Laura Pedretti, Alessia Giarola, Mandy Korff, John Lambert, Claudia Meisina
Subsidence refers to the gradual lowering or sudden sinking of the ground surface and is known to impact human lives in terms of damages to the infrastructures, utility lines, and buildings as well as changes in the surficial drainage systems and groundwater conditions. The impacts of land subsidence will be greater in the future, considering the sea level rise, population growth, intensification of coastal erosion and extreme events, as well as increase in flood risk or freshwater salinization, mostly in coastal cities. The main aim of this work is to provide an open-source, peer-reviewed, and comprehensive database identifying the main and secondary causes of land subsidence in 143 coastal cities. We highlight the potential impacts of subsidence that are still unknown in some at-risk cities and non-existence of mitigation measures. The database additionally shows that mitigation measures, specifically those addressing subsidence due to groundwater extraction, have proven successful in the past. The proposed database aims to increase the knowledge on the subsidence phenomenon and also global awareness of land subsidence issues among researchers, the scientific community, stakeholders, and policymakers in terms of urban planning and development.
众所周知,地面沉降是指地表逐渐降低或突然下沉,会对人类生活造成影响,对基础设施、公用设施线路和建筑物造成破坏,并改变地表排水系统和地下水状况。考虑到海平面上升、人口增长、海岸侵蚀加剧和极端事件的发生,以及洪水风险增加或淡水盐碱化(主要是在沿海城市),未来地面沉降的影响将更大。这项工作的主要目的是提供一个开源的、经过同行评审的综合数据库,确定 143 个沿海城市土地沉降的主要和次要原因。我们强调了在一些高风险城市仍不为人知的沉降潜在影响,以及不存在的缓解措施。该数据库还显示,缓解措施,特别是解决地下水开采引起的沉降问题的措施,在过去已被证明是成功的。拟议的数据库旨在增加研究人员、科学界、利益相关者和城市规划与发展决策者对沉降现象的了解,以及对全球土地沉降问题的认识。
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引用次数: 0
Deep-learning-based natural fracture identification method through seismic multi-attribute data: a case study from the Bozi-Dabei area of the Kuqa Basin, China 基于深度学习的地震多属性数据天然断裂识别方法:中国库车盆地博孜-大北地区案例研究
IF 2.9 3区 地球科学 Q3 GEOSCIENCES, MULTIDISCIPLINARY Pub Date : 2024-08-26 DOI: 10.3389/feart.2024.1468997
Yongliang Tang, Dong Chen, Hucheng Deng, Fenglai Yang, Haiyan Ding, Yuyong Yang, Cuili Wang, Xiaofei Hu, Naidong Chen, Chuan Luo, Ming Tang, Yu Du
Fractures play a crucial role in tight sandstone gas reservoirs with low permeability and low effective porosity. If open, they not only significantly increase the permeability of the reservoir but also serve as channels connecting the storage space. Among numerous fracture identification methods, seismic data provide unique advantages for fracture identification owing to the provision of three-dimensional information between wells. How to accurately identify the development of fractures in geological bodies between wells using seismic data is a major challenge. In this study, a tight sandstone gas reservoir in the Kuqa Basin (China) was used as an example for identifying reservoir fractures using deep-learning-based method. First, a feasibility analysis is necessary. Intersection analysis between the fracture density and seismic attributes (the characteristics of frequency, amplitude, phase, and other aspects of seismic signals) indicates that there is a correlation between the two when the fracture density exceeds a certain degree. The development of fractures is closely related to the lithology and structure, indirectly affecting differences in seismic attributes. This indicates that the use of seismic attributes for fracture identification is feasible and reasonable. Subsequently, the effective fracture density data obtained from imaging logging were used as label data, and the optimized seismic attribute near the well data were used as feature data to construct a fracture identification sample dataset. Based on a feed-forward neural network algorithm combined with natural fracture density and effectiveness control factor constraints, a trained identification model was obtained. The identification model was applied to seismic multi-attribute data for the entire work area. Finally, the accuracy of the results from the training, testing, and validation datasets were used to determine the effectiveness of the method. The relationship between the fracture identification results and the location of the fractures in the target reservoir was used to determine the reasonableness of the results. The results indicate that there is a certain relationship between multiple seismic attributes and fracture development, which can be established using deep learning models. Furthermore, the deep-learning-based seismic data fracture identification method can effectively identify fractures in the three-dimensional space of reservoirs.
在低渗透率和低有效孔隙度的致密砂岩气藏中,裂缝起着至关重要的作用。如果裂缝开放,不仅能显著提高储层的渗透率,还能成为连接储集空间的通道。在众多的裂缝识别方法中,地震数据由于可以提供井间三维信息,为裂缝识别提供了独特的优势。如何利用地震数据准确识别井间地质体的裂缝发育情况是一大挑战。本研究以中国库车盆地致密砂岩气藏为例,采用基于深度学习的方法识别储层裂缝。首先,需要进行可行性分析。裂缝密度与地震属性(地震信号的频率、振幅、相位等特征)的交集分析表明,当裂缝密度超过一定程度时,两者之间存在相关性。裂缝的发育与岩性和构造密切相关,间接影响地震属性的差异。这说明利用地震属性进行断裂识别是可行的、合理的。随后,以成像测井获得的有效裂缝密度数据为标签数据,以优化后的近井地震属性数据为特征数据,构建了裂缝识别样本数据集。基于前馈神经网络算法,结合天然裂缝密度和有效性控制因子约束,得到了训练有素的识别模型。该识别模型被应用于整个工作区的地震多属性数据。最后,利用训练、测试和验证数据集结果的准确性来确定该方法的有效性。裂缝识别结果与目标储层中裂缝位置之间的关系用于确定结果的合理性。结果表明,多种地震属性与裂缝发育之间存在一定的关系,可以利用深度学习模型建立这种关系。此外,基于深度学习的地震数据裂缝识别方法能够有效识别储层三维空间中的裂缝。
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引用次数: 0
A depleted mantle source for Neoproterozoic continental rifting in the Seve Nappe Complex, Kebnekaise region, northern Swedish Caledonides 瑞典喀里多尼亚山脉北部凯布奈凯斯地区塞夫岩层群中新近纪大陆漂移的贫化地幔源
IF 2.9 3区 地球科学 Q3 GEOSCIENCES, MULTIDISCIPLINARY Pub Date : 2024-08-26 DOI: 10.3389/feart.2024.1426525
Riccardo Callegari, Abigail K. Barker, Christopher J. Barnes, Katarzyna Walczak, Grzegorz Ziemniak, Iwona Klonowska, Ellen Kooijman, Sabine Rousku, Karolina Kośmińska, Jarosław Majka
The Central Iapetus Magmatic Province (CIMP) is a large igneous province (LIP) emplaced in the Baltican and Laurentian paleocontinents that marks the onset of the Caledonian Wilson Cycle. Paleozoic magmatism of the CIMP is preserved in both northeastern America and northern Europe. This study investigates rocks belonging to the hyper-extended margin of Baltica currently found in the Seve Nappe Complex of the Scandinavian Caledonides. Specifically, U-Pb zircon geochronology and whole-rock geochemistry are applied to a migmatitic variety of the Vierručohkka amphibolite of the Mårma Terrane, to the Aurek gabbro, and amphibolite of the Aurek Assemblage exposed in the Seve Nappe Complex in the Kebnekaise region, northern Swedish Caledonides. U-Pb zircon geochronology yields crystallization ages of 626 ± 7 Ma for the protolith of the Vierručohkka amphibolite, and 614 ± 2 Ma and 609 ± 1 Ma for the emplacement of the Aurek gabbro and amphibolite protolith, respectively. A younger age of 599 ± 3 Ma is recorded in the Vierručohkka amphibolite and is interpreted as the age of partial melting and migmatization. The geochemical signatures of the rocks demonstrate crustal assimilation during the emplacement of their protoliths and modification due to prograde metamorphic processes during Caledonian subduction. The Vierručohkka amphibolite and the Aurek Assemblage samples display upper and lower crustal assimilation, respectively. Trace elements (Dy, Sm, Lu, and Y) record the growth of metamorphic garnet, while elevated TiO2 contents record the crystallization of metamorphic rutile. Nevertheless, high field strength elements (HSFE) and ∆Nb suggest a depleted mantle source for the magmas of the protoliths of the investigated rocks. Altogether, geochemical data indicate that the igneous activity recorded in the Vierručohkka amphibolite and the Aurek Assemblage between c. 626–609 Ma is related to continental rifting processes associated with the opening of the Iapetus Ocean.
中央伊佩图斯岩浆省(CIMP)是一个大型火成岩省(LIP),位于波罗的海和劳伦廷古陆,标志着喀里多尼亚威尔逊周期的开始。CIMP的古生代岩浆活动保存在美洲东北部和欧洲北部。本研究调查了目前在斯堪的纳维亚喀里多尼亚山脉塞夫斜长岩群中发现的属于波罗的海超延伸边缘的岩石。具体地说,U-Pb 锆石地质年代学和全岩地球化学被应用于 Mårma Terrane 的 Vierručohkka 闪长岩中的一个偏闪长岩品种、Aurek 辉长岩以及出露于瑞典喀里多尼亚山脉北部 Kebnekaise 地区 Seve Nappe 复合体中 Aurek 组合的闪长岩。U-Pb锆石地质年代学得出,Vierručohkka闪长岩原岩的结晶年龄为626±7Ma,Aurek辉长岩和闪长岩原岩的成岩年龄分别为614±2Ma和609±1Ma。Vierručohkka闪长岩的记录年龄较小,为 599 ± 3 Ma,被解释为部分熔融和迁移的年龄。这些岩石的地球化学特征表明,其原岩在形成过程中被地壳同化,并在喀里多尼亚俯冲过程中因原生变质过程而发生变化。Vierručohkka 闪长岩和 Aurek 组合样本分别显示了上地壳同化和下地壳同化。痕量元素(Dy、Sm、Lu 和 Y)记录了变质石榴石的生长过程,而二氧化钛含量的升高则记录了变质金红石的结晶过程。然而,高场强元素(HSFE)和∆Nb表明,调查岩石原岩的岩浆来源于贫乏的地幔。总之,地球化学数据表明,在约 626-609 Ma 之间,Vierručohkka 闪长岩和 Aurek 组合记录的火成岩活动与伊阿佩托斯洋开辟时的大陆漂移过程有关。
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引用次数: 0
Experimental study on dynamic interaction between ground fissure and diagonal three-section subway tunnels 地裂缝与对角线三截面地铁隧道之间动态相互作用的试验研究
IF 2.9 3区 地球科学 Q3 GEOSCIENCES, MULTIDISCIPLINARY Pub Date : 2024-08-23 DOI: 10.3389/feart.2024.1453210
Lei Liu, Zhilin Ren, Weiheng Peng, Jinkai Yan
Ground fissures, as a typical geohazard, pose potential georisks to the construction and maintenance of urban transportation infrastructure. Under the influence of ground fissures, the segmented tunnel structure used in subway systems complicates the propagation of subway train vibrations. In this study, the soil acceleration, earth pressure and contact pressure of a three-section subway tunnel under dynamic loading of a subway train in a ground fissure environment were observed and analyzed by physical modeling tests, and the effects of the presence and activity of the ground fissure and tunnel segmentation were discussed. The results show that the vibration generated by the subway traveling will have different degrees of attenuation when propagating in all directions in the soil layer, and the ground fissure has a damping effect on the subway vibration. The attenuation and enhancement of acceleration by ground fissure is affected by the activity and propagation direction of ground fissure. The distribution of additional earth pressure is affected by the ground fissure, soil contact state, which is related to the ground fissure activity state. The ground fissure activity on the contact additional pressure mainly focuses on the bottom and top of the tunnel and there are differences in the location of the hanging wall and footwall. Three-section tunnels have a stronger vibration response and vibration attenuation than monolithic tunnels due to the influence of segmentation. Based on the consideration of the effects of ground fissure and tunnel segmentation, the tunnel design mainly takes into account the amount of ground fissure activity and determines the structural measures, the tunnel structure at the location of the ground fissure is strengthened, in addition to the vibration attenuation measures for the segmented tunnels when crossing the ground fissure. The discussion of mechanical response and design measures in this study helps to reduce the georisk of ground fissures on urban underground transportation infrastructure.
地裂缝作为一种典型的地质灾害,给城市交通基础设施的建设和维护带来了潜在的地质风险。在地裂缝的影响下,地铁系统采用的分段式隧道结构使地铁列车振动的传播变得更加复杂。本研究通过物理模型试验,观察和分析了地裂缝环境下地铁列车动态载荷作用下三节地铁隧道的土体加速度、土压力和接触压力,并讨论了地裂缝的存在和活动以及隧道分段的影响。结果表明,地铁行驶产生的振动在土层中向各个方向传播时会有不同程度的衰减,地裂缝对地铁振动有阻尼作用。地裂缝对加速度的衰减和增强作用受地裂缝活动性和传播方向的影响。附加土压力的分布受地层裂隙、土壤接触状态的影响,与地层裂隙活动状态有关。地裂缝活动对接触附加压力的影响主要集中在隧道底部和顶部,在挂壁和底壁位置存在差异。由于分段的影响,三段式隧道比整体式隧道具有更强的振动响应和振动衰减。在考虑地裂缝和隧道分段影响的基础上,隧道设计主要考虑地裂缝的活动量,确定结构措施,对地裂缝位置的隧道结构进行加固,另外对分段隧道在穿越地裂缝时采取减振措施。本研究对机械响应和设计措施的讨论有助于降低地裂缝对城市地下交通基础设施造成的地质风险。
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引用次数: 0
Understanding the spatio-temporal behaviour of riverine plastic transport and its significance for flux determination: insights from direct measurements in the Austrian Danube River 了解河流塑料迁移的时空行为及其对通量确定的意义:奥地利多瑙河直接测量的启示
IF 2.9 3区 地球科学 Q3 GEOSCIENCES, MULTIDISCIPLINARY Pub Date : 2024-08-22 DOI: 10.3389/feart.2024.1426158
Sebastian Pessenlehner, Philipp Gmeiner, Helmut Habersack, Marcel Liedermann
Plastic pollution in aquatic environments is a growing concern, with rivers recognized as major pathways. However, rivers themselves are also subject to pollution. Hence, understanding riverine plastic transport dynamics is essential for mitigating environmental impacts. Although plastic-related research focus has shifted from marine environments towards rivers, challenges remain in standardizing methods for monitoring and integrating spatio-temporal variabilities of riverine plastic occurrence into flux determination. This study addresses these challenges by adopting established methods from sediment research. Utilizing data from a net-based cross-sectional multi-point approach, it examines spatio-temporal and discharge-dependent variations. It comprehensively analyzes the complex dynamics of plastic transport in the Danube River, contrasting an impounded section near Aschach, Austria, with a free-flowing reach near Hainburg, Austria. The paper emphasizes the significance of applying these methodologies for accurate flux determination and underscores the risks of neglecting them. By incorporating average microplastic particle weights, we aim to overcome limitations in prior methodologies that solely emphasize qualitative aspects or rely on item numbers. Spatial distribution analysis revealed a pronounced stratification at low flow and a more variable distribution in the free-flowing section, attributed to higher turbulence. As discharge increased, vertical mixing occurred, along with distinct lateral patterns displaying increased concentrations toward the riverbanks. Encountering plastic particles throughout the river profile underscores their properties of both suspended and floating matter, emphasizing the importance of hydro-morphology and multi-point cross-sectional measurement approaches. Microplastic loads were calculated to be &lt;6.9 t a−1 in Aschach and &lt;17.1 t a−1 in Hainburg, compared to total plastic loads of &lt;14.3 t a−1 in Aschach and &lt;41.6 t a−1 in Hainburg. Consequently, plastic loads were doubled to tripled within the Austrian section of the Danube River. The study contributes valuable insights into the complex nature of plastic transport in river systems, emphasizing comprehensive spatial, temporal and discharge-dependent assessments for characterizing and managing plastic pollution. It suggests that rivers can function as sources, pathways and sinks of plastic pollution, contingent upon hydro-morphological conditions. This underscores the need for longitudinal, basin-wide assessments to accurately understand plastic transport dynamics.
水生环境中的塑料污染日益受到关注,而河流被认为是主要的污染途径。然而,河流本身也会受到污染。因此,了解河流塑料迁移动态对于减轻环境影响至关重要。尽管与塑料相关的研究重点已从海洋环境转向河流,但在标准化监测方法以及将河流塑料发生的时空变化纳入通量确定方面仍存在挑战。本研究采用沉积物研究的既定方法来应对这些挑战。利用基于网状断面的多点方法获得的数据,研究了时空变化和与排水量相关的变化。论文全面分析了多瑙河塑性迁移的复杂动态,将奥地利阿沙赫附近的蓄水河段与奥地利海恩堡附近的自由流动河段进行了对比。论文强调了应用这些方法准确测定通量的重要性,并强调了忽视这些方法的风险。通过纳入微塑料颗粒的平均重量,我们旨在克服以往方法中仅强调定性或依赖项目数量的局限性。空间分布分析表明,在低流量时有明显的分层现象,而在自由流动段的分布则更加多变,这归因于较高的湍流。随着排水量的增加,出现了垂直混合现象,同时显示出明显的横向模式,即向河岸的浓度增加。在整个河流剖面上都能遇到塑料微粒,这突出了它们既是悬浮物又是漂浮物的特性,强调了水文形态学和多点断面测量方法的重要性。经计算,阿沙赫和海恩堡的微塑料负荷分别为 &lt;6.9 t a-1 和 &lt;17.1 t a-1,而阿沙赫和海恩堡的总塑料负荷分别为 &lt;14.3 t a-1 和 &lt;41.6 t a-1。因此,多瑙河奥地利河段的塑性负荷增加了一倍到两倍。这项研究对河流系统中塑料迁移的复杂性提供了宝贵的见解,强调了对塑料污染的特征描述和管理进行全面的空间、时间和排放评估。研究表明,河流可作为塑料污染的源头、途径和汇,这取决于水文地貌条件。这强调了进行纵向、全流域评估以准确了解塑料迁移动态的必要性。
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引用次数: 0
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Frontiers in Earth Science
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