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Primary Porosity and Permeability of Hypabyssal Dikes:A Case Study of the Miocene Hypabyssal Dikes in Lyttelton Volcano,New Zealand 认领 引用
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作者 Huafeng Tang Tianchan Guo +1 位作者 Hanfei Wang Jingsong Hu 《Journal of Earth Science》 SCIE CAS CSCD 2026年第1期214-228,共15页
Dikes are widely distributed in volcanic outcrops and volcanic basins around the world.The pores and fractures in these dikes control the fluid-rock interactions and fluid flow.The quantitative reservoir characteristi... Dikes are widely distributed in volcanic outcrops and volcanic basins around the world.The pores and fractures in these dikes control the fluid-rock interactions and fluid flow.The quantitative reservoir characteristics of dikes with primary vesicles remain unclear.In this manuscript,the Miocene hypabyssal dikes in Lyttelton Volcano,Christchurch,New Zealand,are taken as an example.The porosity content,porosity,permeability,and reservoir controlling factors are analyzed through field outcrop surveys,porosity-permeability testing,nuclear magnetic resonance(NMR)testing,X-ray-computed tomography(X-CT)scanning,and permeability calculations.The results show that the types of reservoir spaces in the hypabyssal dikes in Lyttelton Volcano are mainly vesicles,followed by cooling and shrinkage fractures(especially columnar joints).They are a pore-fracture type reservoir.There were two types of vesicles,namely,pipe-like-elliptical directionally oriented vesicles with large diameters and discrete circular vesicles with small diameters.The surface porosity of the former was 58.4%–96.0%,with a geometric mean of 78.9%.The columnar joints can be classified into regular and irregular joints.The irregular joints have a higher fracture intensity.The geometric means of the porosity and permeability of the joints are 22.34%and 0.09×10-15m2,respectively.The shapes of the NMR T2spectra are bimodal,trimodal,and unimodal in descending order of abundance.This means that the pore diameter is large.The X-CT results indicate that there are four types of pore-throat connectivity modes:macro-pores and macro-throats,macro-pores and micro-throats,micro-pores and micro-throats,and micro-pores and macrothroats.The columnar joints are the main cause of the high permeability of the dikes,and the side amount and side length of the columnar joints control the dikes'permeability.The pores can be connected by the columnar joints,and their connectivity is controlled by the side amount,side length,and side azimuth of the columnar joint.The initial connectivity ratio of the vesicles in the dikes in Lyttelton Volcano was up to 47.6%based on the surface porosity.In conclusion,the shallow dikes with primary pores and fractures have a good reservoir quality and fluid migration capacity,and fluid flow studies of volcanic strata should pay attention to the important influence of the primary porosity and permeability of dikes. 展开更多
关键词 Lyttelton Volcano Miocene hypabyssal dikes columnar joints distribution pattern of reservoirs
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Environmental and Hydraulic Considerations in Scour Reduction Around Spur Dikes:A Comprehensive Review 认领 引用 被引量：1
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作者 Ismail Hashim Hussein Asmaa Abdul Jabbar Jamel Raad Hoobi Irzooki 《Sustainable Marine Structures》 2025年第3期117-135,共19页
Spur dikes are essential hydraulic structures extensively used in river engineering to control bank erosion,regulate river flow,and enhance navigation.Despite their benefits,spur dikes interact with complex hydrodynam... Spur dikes are essential hydraulic structures extensively used in river engineering to control bank erosion,regulate river flow,and enhance navigation.Despite their benefits,spur dikes interact with complex hydrodynamic forces that lead to vortex-induced scouring at their base,which threatens their structural stability and affects the surrounding ecosystem.This paper presents a comprehensive review that combines findings from experimental and numerical studies to explain the mechanisms of scour development around spur dikes,with a particular focus on installations in curved river channels.The review examines how hydraulic,geometric,and material parameters,such as flow velocity,dike location,alignment,shape,and porosity,affect scour depth and extent.Results from previous studies reveal that spur dikes placed near the outer bends of rivers experience more severe scouring due to stronger secondary circular flow and increased sediment entrainment.However,optimizing the spacing,orientation,and geometry of spur dikes can significantly reduce scour,in some cases by up to 80%.The paper also explores the role of dike porosity and material selection in mitigating adverse hydraulic impacts while supporting aquatic habitat diversity.By synthesizing these findings,the review provides practical design recommendations to enhance spur dike performance,minimize scour-related damages,and improve their environmental sustainability.The insights from this study can guide engineers and planners in designing more efficient and eco-friendly spur dike systems for river management and restoration projects. 展开更多
关键词 Spur Dikes Angle of Spur Dikes Porosity Shape of Spur Dike Scour
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Hydraulic performance assessment of various submerged pile designs around an emerged dike 认领 引用 被引量：2
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作者 Sohail Iqbal Norio Tanaka 《Water Science and Engineering》 EI CAS CSCD 2024年第4期406-416,共11页
This study aimed to devise strategies for alleviating the detrimental impacts of floods in the vicinity of a dike. Experiments were conducted in an open rectangular channel to investigate the flow dynamics under varyi... This study aimed to devise strategies for alleviating the detrimental impacts of floods in the vicinity of a dike. Experiments were conducted in an open rectangular channel to investigate the flow dynamics under varying dike conditions. To address concerns related to intense whirls and concentrated flow around the dike head, comparative analysis was performed in terms of flow structures and energy reduction around I-shaped and T-shaped dikes with two ratios of wing length (lw) to dike length (ld) (lw/ld = 1.41 and 2.43). The T-shaped dike wings were equipped with diverse designs: angled footing, delta vane, and streamlined tapered, resulting in elevated backwater in front of the dike, reduced velocity, and enhanced energy reduction. The findings indicated that elongating the wing reciprocally affected the depth-averaged velocity (at the dike head and near the adjacent dike bank), concurrently impacting flow deflection, backwater rise, and energy reduction rate. The T-shaped dike, specifically with an angled footing (lw/ld = 2.43), yielded optimal outcomes. These included significant reductions in maximum energy (46%), tip velocity (98%), and dike adjacent bank velocity (90%), as well as significant flow deflection towards the mainstream, outperforming the I-shaped impermeable dike. The proposed solutions exhibit efficacy in mitigating rapid deterioration during floods, securing both the dike head and the neighboring bank to avert failures in high-energy flow. 展开更多
关键词 Pile wings T-shaped dike I-shaped dike Impermeable dike Submerged pile designs
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Estimation of scour depth at a single non-submerged vertical spur dike under unidirectional currents 认领 引用
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作者 HtayHtay Aung Min-xi Zhang +2 位作者 Giuseppe Oliveto Beniamino Onorati Guo-liang Yu 《Water Science and Engineering》 EI CAS CSCD 2025年第4期527-536,共10页
Accurately estimating equilibrium scour depths at spur dikes remains challenging due to the complexity of scour around these structures.Scour critically threatens spur dikes built in river estuaries for enhancing navi... Accurately estimating equilibrium scour depths at spur dikes remains challenging due to the complexity of scour around these structures.Scour critically threatens spur dikes built in river estuaries for enhancing navigability and preventing bank erosion.This study conducted 41 experiments to determine the approach flow velocity corresponding to scour initiation at a non-submerged spur dike,which enables prediction of equilibrium scour depth.The results showed that scour incipient velocity depended on spur geometry,approach flow characteristics,and sediment properties,rather than being a fixed value.A new formula for equilibrium scour depth prediction was proposed,based on the scour incipient velocity and the excess abutment Froude number,yielding a determination coefficient of 0.93.The formula demonstrated broader applicability and greater accuracy than previously reported formulas,with 98%of data within a±25%error margin.The dimensionless sediment size was introduced to capture the effects of sediment size on scour,providing an alternative to the sediment coarseness ratio,which is challenging to replicate in laboratory settings.These findings offer valuable guidance for engineering design and protection of spur dikes under unidirectional flow. 展开更多
关键词 Scour initiation Scour depth Excess abutment Froude number Spur dike Dimensionless sediment size
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Risk Analysis and Assessment of Overtopping Concerning Sea Dikes in the Case of Storm Surge 认领 引用 被引量：7
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作者 王莉萍 黄桂玲 +2 位作者 陈正寿 梁丙臣 刘桂林 《China Ocean Engineering》 SCIE EI CSCD 2014年第4期479-487,共9页
Risk analysis and assessment relating coastal structures has been one of the hot topics in the area of coastal protection recently. In this paper, from three aspects of joint return period of multiple loads, dike fail... Risk analysis and assessment relating coastal structures has been one of the hot topics in the area of coastal protection recently. In this paper, from three aspects of joint return period of multiple loads, dike failure rate and dike continuous risk prevention respectively, three new risk analysis methods concerning overtopping of sea dikes are developed. It is worth noting that the factors of storm surge which leads to overtopping are also considered in the three methods. In order to verify and estimate the effectiveness and reliability of the newly developed methods, quantified mutual information is adopted. By means of case testing, it can be found that different prior variables might be selected dividedly, according to the requirement of special engineering application or the dominance of loads. Based on the selection of prior variables, the correlating risk analysis method can be successfully applied to practical engineering. 展开更多
关键词 sea dikes risk analysis failure rate mutual information
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Geochemical Characteristics and Genesis of the Luxi-Xianrenzhang Diabase Dikes in Xiazhuang Uranium Orefield, Northern Guangdong Province 认领 引用 被引量：17
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作者 LING Hongfei SHEN Weizhou +5 位作者 DENG Ping JIANG Shaoyong JIANG Yaohui YE Haimin PU Wei TAN Zhengzhong 《Acta Geologica Sinica(English Edition)》 SCIE CAS 2005年第4期497-506,共10页
The Luxi-Xianrenzhang diabase dikes were emplaced into the eastern part of the Guidong composite granitoids in northern Guangdong Province at the end of the Early Cretaceous. They show tholeiitic features, enrichment ... The Luxi-Xianrenzhang diabase dikes were emplaced into the eastern part of the Guidong composite granitoids in northern Guangdong Province at the end of the Early Cretaceous. They show tholeiitic features, enrichment in large ion lithophile elements, slight enrichment in light rare earth elements, depletion in Zr and Hf, and basically no depletion in Nb and Ta and no Eu anomaly. They are similar to intraplate basalt in terms of trace element characteristics. They have high εNd（t） values （3.6-4.9）, initial ^87Sr/^86Sr ratios （0.70530-70641） and δ^18O values and Dupal anomaly of Pb isotope compositions. Their Sr-Nd, Pb-Sr, Pb-Nd and Pb-Pb isotopes plot between DMM and EMII, with Pb similar to EMII, Nd relatively close to DMM and Sr in between. This profile suggests that the diabase dikes studied were derived from partial melting of a mantle source that had been subjected to metasomatism by fluids originated from a subduction zone under a tectonic environment of crustal extension and lithosphere thinning in the late Yanshanian. 展开更多
关键词 geochemistry main and trace elements Nd-Sr-Pb-O isotopes diabase dikes Guangdong
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Early Eocene leucocratic sill/dike swarms in the Gangdese belt,southern Tibet:Tectonic implications for Indo-Asian collision 认领 引用 被引量：11
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作者 Xu-xuan Ma Li-E Gao +2 位作者 Zhong-bao Zhao Xi-jie Chen Hai-bing Li 《China Geology》 CAS CSCD 2021年第1期56-66,共11页
The timing of the initial Indo-Asian collision is a subject of debate for a long time.Besides,the magmatic trace of the collisional process is also unclear.In the present study,the authors report Early Eocene leucocra... The timing of the initial Indo-Asian collision is a subject of debate for a long time.Besides,the magmatic trace of the collisional process is also unclear.In the present study,the authors report Early Eocene leucocratic sill/dike swarms in the northern edge of the Nymo intrusive complex of the Gangdese belt,southern Tibet.The Nymo intrusive complex was emplaced at ca.50–47 Ma and surrounded by the metamorphosed Jurassic-aged Bima Formation volcano-sedimentary sequence along its northern side.At outcrops,the leucocratic sills/dikes intruded along or truncated the deformed foliations of the host Bima Formation,which has been subject to high-temperature amphibolite-facies metamorphism at ca.50–47 Ma.Detailed cathodoluminescence image analyses reveal that the zircon grains of the leucocratic sills/dikes have core-mantle textures.The cores yield the Jurassic ages comparable to the protolith ages of the Bima Formation.In contrast,the mantles of zircon grains yield weighted mean ages of ca.49–47 Ma,representing the crystallization timing of these leucocratic sills/dikes.The coeval ages for the Nymo intrusive complex,the high-temperature metamorphism,and the leucocratic sills/dikes indicate that a close relationship exists among them.The authors tentatively suggest that these leucocratic sills/dikes were generated from partial melting of the Jurassic-aged Bima Formation volcanic rocks,triggered by the high heat from the magma chamber of the Nymo intrusive complex.This Early Eocene tectono-thermal event of coeval magmatism,metamorphism and partial melting was most likely formed during the Indo-Asian collisional setting. 展开更多
关键词 Leucocratic sill/dike swarm Early Eocene Indo-Asian collision Gangdese Tibet China
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Stability of the Guiding Dike in Yangtze Estuary Under the Wave Load 认领 引用 被引量：7
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作者 闫澍旺 刘润 +1 位作者 范期锦 谢世楞 《China Ocean Engineering》 SCIE EI 2005年第4期659-670,共12页
During the construction of the guiding dike in the Yangtze Estuary, some of the caisson structures sank into the soil for 1 -5 m or slid about 20 m away from the original place when a strong storm attacked this area. ... During the construction of the guiding dike in the Yangtze Estuary, some of the caisson structures sank into the soil for 1 -5 m or slid about 20 m away from the original place when a strong storm attacked this area. Dynamic triaxial tests were carried out to simulate the behavior of foundation soils under wave loading. The test results show that the excessive settlement and lateral movement of the caissons are due to the weakening of the soft clay strength during the strong storm. The test results also show that the ability of the soft clay to resist the wave force will be greatly increased when the soft soil samples are suitably improved. Based on the test results, an improvement method combining vertical drains with surcharge loading was proposed to strengthen the foundation soil. On the improved soil foundation, the dike has been reconstructed and undergone several strong storms without any damage. A finite element approach has been developed for analyzing the settlement and stability of the dike under the action of strong storm. 展开更多
关键词 soft clay strength weakening dike dynamic triaxial test FE analysis
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Minimum critical thickness of dike for ore-bearing fluid injection:A new approach applied to the Shihu gold deposit,Hebei Province,North China 认领 引用 被引量：6
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作者 Dedong Li Yuwang Wang +4 位作者 Jingbin Wang Zhaohua Luo Jiulong Zhou Zongfeng Yang Cui Liu 《Geoscience Frontiers》 SCIE CAS 2012年第5期717-728,共12页
According to the metallogenic theory by transmagmatic fluid （TMF）, one magmatic intrusion is a channel of ore-bearing fluids, but not their source. Therefore, it is possible to use TMF＇s ability for injection into ... According to the metallogenic theory by transmagmatic fluid （TMF）, one magmatic intrusion is a channel of ore-bearing fluids, but not their source. Therefore, it is possible to use TMF＇s ability for injection into and for escaping t^om the magmatic intrusion to evaluate its ore-forming potential. As the ore-bearing fluids cannot effectively inject into the magmatic intrusion when the magma fully crystal- lized, the cooling time and rates viscosity varied can be used to estimate the minimum critical thickness of the intrusion. One dimensional heat transfer model is used to determine the cooling time for three representative dikes of different composition （granite porphyry, quartz diorite and diabase） in the Shihu gold deposit. It also estimated the rates viscosity varied in these time interval. We took the thickness of dike at the intersection of the cooling time -- thickness curve and the rates viscosity varied versus thick- ness curve as the minimum critical thickness. For the ore-bearing fluids effectively injecting into the magma, the minimum critical thicknesses for the three representative dikes are 33.45 m for granite porphyry, 8.22 m for quartz diorite and 1.02 m for diabase, indicating that ore-bearing dikes must be thicker than each value. These results are consistent with the occurrence of ore bodies, and thus they could be applied in practice. Based on the statistical relationship between the length and the width of dikes, these critical thicknesses are used to compute critical areas： 0.0003--0.0016 km2 for diabase, 0.014--0.068 km2 for quartz diorite and 0.011-0.034 km2 for granite porphyry. This implies that ore- bearing minor intrusions have varied areas corresponding to their composition. The numerical simulation has provided the theoretical threshold of exposed thickness and area of the ore-bearing intrusion. These values can be used to determine the ore-forming potentials of dikes. 展开更多
关键词 Dike swarm Cooling time Numerical simulationMinor intrusion Critical thickness Transmagmatic fluid
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Discovery of a Sheeted Dike Complex in the Northern Yangtze Craton and Its Implications for Craton Evolution 认领 引用 被引量：7
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作者 邓浩 Timothy M Kusky +4 位作者 王璐 彭松柏 蒋幸福 王军鹏 王淞杰 《Journal of Earth Science》 SCIE EI CAS CSCD 2012年第5期676-695,共20页
The Miaowan （庙湾） ophiolite is a highly dismembered ophiolitic complex cropping out near the northern margin of the Yangtze craton. The rocks of this complex consist of, from bottom to top, harzburgite tectonite lo... The Miaowan （庙湾） ophiolite is a highly dismembered ophiolitic complex cropping out near the northern margin of the Yangtze craton. The rocks of this complex consist of, from bottom to top, harzburgite tectonite locally containing podiform chromite, dunite, layered and isotropic gabbro, a sheeted dike complex （SDC）, meta-pillow lavas with chert pods and layers, and tectonically intercalated marble. The SDC is a very important and significant part of the Miaowan ophiolitic sequence, and grades downward into gabbro and ultramafic rocks, and upward into meta-pillow lavas. Some dikes preserve one-way chilled margins, typical of extensional ophiolitic settings, whereas most preserve dou-ble chilled margins, in cases where the chilling direction can be determined. The SDC is mainly com-posed of meta-diabase （dolerite）, meta-plagiogranite, and small amounts of meta-gabbro and ultramafic rocks. LA-ICP-MS zircon dating yields an upper intercept age of 1 026±79 Ma for one meta-plagiogranite, 1 043±23 Ma for a second meta-plagiogranite and I 096±32 Ma for one meta-gabbro at the bottom of the SDC, suggesting formation of the SDC at circa 1 026-1 096 Ma, consistent with the recently determined formation age of the Miaowan ophiolite. Sparse geochemical data on the meta-diabase indicate that the protolith was a sub-alkaline, low-potassium tholeiite similar to mid-ocean ridge basalt （MORB）. The chondrite-normalized rare earth element （REE） patterns of the meta-diabase are generally flat （（La/Yb）N=0.56-0.94）, with a slight depletion in LREE, but no obvious Eu anomalies. Given that the meta-plagiogranites show evidence of formation in a suprasubduction zone environment, we suggest that the basalts were originally island arc tholeiites, perhaps formed in an extensional forearc setting. The geochemistry of the meta-diabase and plagiogranite from the sheeted dikes, together with regional relationships, all agree with the previous interpretations that the Miaowan ophiolite formed in a suprasubduction zone setting. 展开更多
关键词 ophiolite sheeted dike complex Yangtze craton Rodinia.
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Simulation of flow pattern at rectangular lateral intake with different dike and submerged vane scenarios 认领 引用 被引量：6
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作者 Hojat Karami Saeed Farzin +1 位作者 Mohammad Tavakol Sadrabadi Hasan Moazeni 《Water Science and Engineering》 EI CAS CSCD 2017年第3期246-255,共10页
A comprehensive understanding of the sediment behavior at the entrance of diversion channels requires complete knowledge of threedimensional(3 D) flow behavior around such structures. Dikes and submerged vanes are typ... A comprehensive understanding of the sediment behavior at the entrance of diversion channels requires complete knowledge of threedimensional(3 D) flow behavior around such structures. Dikes and submerged vanes are typical structures used to control sediment entrainment in the diversion channel. In this study, a 3 D computational fluid dynamic(CFD) code was calibrated with experimental data and used to evaluate flow patterns, the diversion ratio of discharge, the strength of secondary flow, and dimensions of the vortex inside the channel in various dike and submerged vane installation scenarios. Results show that the diversion ratio of discharge in the diversion channel is dependent on the width of the flow separation plate in the main channel. A dike perpendicular to the flow with a narrowing ratio of 0.20 doubles the ratio of diverted discharge in addition to reducing suspended sediment input to the basin, compared with a no-dike situation, by creating the outer arch conditions. A further increase in the narrowing ratio decreases the diverted discharge. In addition, increasing the longitudinal distance between consecutive vanes(Ls) increases the velocity gradient between the vanes and leads to a more severe erosion of the bed, near the vanes. 展开更多
关键词 Three-dimensional simulation Computational fluid dynamics Submerged vanes Dike Side and vortex flow
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Ordovician Granitoids and Silurian Mafic Dikes in the Western Kunlun Orogen, Northwest China:Implications for Evolution of the Proto-Tethys 认领 引用 被引量：4
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作者 ZHANG Qichao WU Zhenhan +3 位作者 LI Shan LI Kan LIU Zhiwei ZHOU Qing 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2019年第1期30-49,共20页
The western Kunlun orogen in the northwest Tibet Plateau is related to subduction and collision of Proto-and Paleo-Tethys from early Paleozoic to early Mesozoic. This paper presents new LA-ICPMS zircon U-Pb ages and L... The western Kunlun orogen in the northwest Tibet Plateau is related to subduction and collision of Proto-and Paleo-Tethys from early Paleozoic to early Mesozoic. This paper presents new LA-ICPMS zircon U-Pb ages and Lu-Hf isotopes, whole-rock major and trace elements, and Sr–Nd isotopes of two Ordovician granitoid plutons(466–455 Ma) and their Silurian mafic dikes(～436 Ma) in the western Kunlun orogen. These granitoids show peraluminous high-K calcalkaline characteristics, with(87Sr/86Sr)_i value of 0.7129–0.7224, εNd(t) values of -9.3 to -7.0 and zircon εHf(t) values of -17.3 to -0.2, indicating that they were formed by partial melting of ancient lower-crust(metaigneous rocks mixed with metasedimentary rocks) with some mantle materials in response to subduction of the Proto-Tethyan Ocean and following collision. The Silurian mafic dikes were considered to have been derived from a low degree of partial melting of primary mafic magma. These mafic dikes show initial 87Sr/86Sr ratios of 0.7101–0.7152 and εNd(t) values of -3.8 to -3.4 and zircon εHf(t) values of -8.8 to -4.9, indicating that they were derived from enriched mantle in response to post-collisional slab break-off. Combined with regional geology, our new data provide valuable insight into late evolution of the Proto-Tethys. 展开更多
关键词 High-K calc-alkaline granitoids mafic dikes Western Kunlun Orogen Proto-Tethys
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Identification of Five Stages of Dike Swarms in the Shanxi-Hebei-Inner Mongolia Border Area and Its Tectonic Implications 认领 引用 被引量：9
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作者 SHAOJi＇an ZHAIMingguo +1 位作者 ZHANGLüqiao LIDaming 《Acta Geologica Sinica(English Edition)》 SCIE EI CAS 2004年第1期320-330,共11页
Dike swarms are generally ascribed to intrusion of mantle-source magma result from extension. Basic dike swarms around the Shanxi-Hebei-Inner Mogolia borders in the northern peripheral area of the North China Craton c... Dike swarms are generally ascribed to intrusion of mantle-source magma result from extension. Basic dike swarms around the Shanxi-Hebei-Inner Mogolia borders in the northern peripheral area of the North China Craton can be divided into five age groups according to isotopic dating: 1800-1700 Ma, 800-700 Ma, 230 Ma, 140-120 Ma, and 50-40 Ma. Geological, petrological and isotope geochemical features of the five groups is investigated in order to explore the variation of the mantle material composition in the concerned area with time. And the various extensional activities reflected by the five groups of dike swarms are compared with some important tectonic events within the North China Craton as well as around the world during the same period. 展开更多
关键词 dike swarms North China Craton extensional events isotopic dating global tectonic movement
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Influence of Spur Dike on Hydrodynamic Exchange Between Channel and Shoal of Generalization Estuary in Physical Model Test 认领 引用 被引量：4
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作者 JIAO Zeng-xiang Dou Xi-ping +2 位作者 ZHENG Jin-hai ZHANG Xin-zhou GAO Xiang-yu 《China Ocean Engineering》 SCIE EI CSCD 2017年第5期624-630,共7页
Widely applied in maintaining estuarial waterway depth, the spur dike has played an important role in currents and sediment exchange between channel and shoal and sediment back-silting in the channel. Through establis... Widely applied in maintaining estuarial waterway depth, the spur dike has played an important role in currents and sediment exchange between channel and shoal and sediment back-silting in the channel. Through establishing a generalized physical model at a bifurcated estuary and conducting current tests under the joint action of runoff and tide, the influence of the spur dike length on current exchange between channel and shoal is analyzed. Results show that when the spur dike length reaches a certain value, the direction of the flow velocity shear front between the channel and shoal will change. The longer the spur dike, the larger the transverse fluctuating velocity at the peak of flood in the channel shoal exchange area, while the transport of the transverse hydrodynamics is obvious in the process of flood. There is an optimum length of spur dike when the shear stress in the channel and the longitudinal velocity in flood and ebb reach the maximum, and the flow velocity will decrease when the spur dike length is smaller or larger than the optimum. For a certain length of spur dike, the larger the channel shoal elevation difference, the larger the peak longitudinal flow velocity in the middle of the navigation channel in flood and ebb. However, the transverse flow velocity will first decrease and then increase. The transverse transportation is obvious when the channel shoal elevation difference increases. 展开更多
关键词 spur dike hydrodynamics flow velocity channel shoal exchange physical model
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Numerical investigation of flow pattern and components of three-dimensional velocity around a submerged T-shaped spur dike in a 90° bend 认领 引用 被引量：4
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作者 Mohammad Vaghefi Yaser Safarpoor Maryam Akbari 《Journal of Central South University》 SCIE EI CAS CSCD 2016年第11期2984-2998,共15页
Spur dike is one of the river training structures. This work presented a numerical simulation of flow field and three-dimensional velocity around a T-shaped spur dike located in bend using SSIIM model. The main object... Spur dike is one of the river training structures. This work presented a numerical simulation of flow field and three-dimensional velocity around a T-shaped spur dike located in bend using SSIIM model. The main objective of this work is to investigate the three-dimensional velocities and streamlines at transverse and longitudinal sections and plan views around the T-shaped spur dike in different submergence ratios(0, 5%, 15%, 25% and 50%). It is concluded that by increasing the submergence ratio from 5% to 50%, the maximum of scour is reduced; the maximum of longitudinal velocity increases by 7.7% and occurs at the water surface in spur dike axis. Near the bed, the maximum of vertical velocity occurs at the end of spur wing. By analyzing the streamlines at transverse sections, the followings were deduced for different submergence ratios: different dimensions and different positions of vortices around the spur dike. 展开更多
关键词 T-shaped spur dike flow pattern submergence ratio SSIIM model
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Experiments and numerical simulations on transport of dissolved pollutants around spur dike 认领 引用 被引量：9
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作者 Li-ping CHEN Jun-cheng JIANG 《Water Science and Engineering》 EI CAS 2010年第3期341-353,共13页
The flow field around a spur dike has three-dimensional characteristics.In order to analyze the influence of the flow field on pollutant transport,based on a compressive volume of fluid(VOF)scheme,the three-dimensiona... The flow field around a spur dike has three-dimensional characteristics.In order to analyze the influence of the flow field on pollutant transport,based on a compressive volume of fluid(VOF)scheme,the three-dimensional transient compressive pollutant transport model(CPTM)and the cubic equation(CE)bounded differencing scheme were developed.For the calibration and validation of CPTM,laboratory experiments were carried out in a flume with a non-submerged spur dike.The spur dike was angled at 60°,90°,and 120°from the upstream direction.The simulation results agreed with the experimental results.The simulations and experiments showed that the distribution of pollutant concentration was determined by circumfluence and the main flow.Concentration decay in the circumfluenee zone was slower than that in the main flow.Downstream of the spur dike,the concentration fluctuation became intensive with the increase of spur dike angle. 展开更多
关键词 VOF spur dike dissolved pollutant numerical simulation experiment
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Geochronology and Geochemistry of Mafic Dikes from Hainan Island and Tectonic Implications 认领 引用 被引量：2
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作者 CAO Jianjin HU Ruizhong +1 位作者 LIU Shen XIE Guiqing 《Acta Geologica Sinica(English Edition)》 SCIE CAS 2009年第6期1064-1073,共10页
In the present study, the major and trace element compositions, as well as Sr, Nd isotopic compositions and K-Ar age data in mafic dikes from Hainan Island, China, have been analyzed. Whole-rock K-Ar dating yielded a ... In the present study, the major and trace element compositions, as well as Sr, Nd isotopic compositions and K-Ar age data in mafic dikes from Hainan Island, China, have been analyzed. Whole-rock K-Ar dating yielded a magmatic duration of 61-98 Ma for mafic dikes. Mafic dikes have a very high concentration of incompatible elements, for example, Ba, Rb, Sr, K, rare earth elements, and especially light rare earth elements （LREE）, and negative anomalies of Nb, Ta, and Ti in the normalized trace element patterns. The initial 87Sr/86Sr ratios and εSr（t） of the mafic dikes are 0.70634- 0.71193 and ＋27.7 to ＋112.2, respectively. In the 87Sr/86Sr versus εNd（t） diagram, the Hainan Island mafic dikes plot between fields for depleted mantle and enriched mantle type 2. All these characteristics show that the mantle （source region） of mafic dikes in this area experienced metasomatism by fluids relatively enriched in LREE and large ion lithophUe elements. The genesis of Hainan Island mafic dikes is explained as a result of the mixing of asthenospheric mantle with lithospheric mantle that experienced metasomatism by the subduction of the Pacific Plate. This is different from the Hainan Island Cenozoic basalts mainly derived from depleted asthenospheric mantle, and possibly, minor metasomatised lithospheric mantle. This study suggests that the Mesozoic and Cenozoic lithospheric revolutions in Hainan Island can be divided into three stages： （1） the compression orogenesis stage before 98 Ma. The dominant factor during this stage is the subduction of the ancient Pacific Plate beneath this area. The lithospheric mantle changed into enriched mantle type 2 by metasomatism; （2） the thinning and extension stage during 61-98 Ma. The dominant factor during this stage is that the asthenospheric mantle invaded and corroded the lithospheric mantle; and （3） the large-scale thinning and extension stage after 61 Ma. The large-scale asthenospheric upwelling results in the strong erupting of Cenozoic basalts, large-scale thinning of the lithosphere, the southward translating and counterclockwise rotating of Hainan Island, and the opening of the South China Sea. 展开更多
关键词 mafic dikes geochemical characteristics tectonic evolution Hainan Island
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Design Methods for Geotextile Tubes Application in Dike Construction 认领 引用 被引量：1
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作者 闫玥 闫澍旺 +1 位作者 邱长林 郑刚 《China Ocean Engineering》 SCIE EI 2008年第3期445-453,共9页
The technique of geotextile tubes used to construct dikes for land reclamation has been widely used. The tubes are usually filled with slun＇y of soil, such as sand, silt or clay. The tensile stress developed in the g... The technique of geotextile tubes used to construct dikes for land reclamation has been widely used. The tubes are usually filled with slun＇y of soil, such as sand, silt or clay. The tensile stress developed in the geotextile during filling the tube is the dominant factor for construction of a safe dike. The existing design methods are good for designing sausage shaped tubes and can not be directly applied for designing fiat tubes, which are commonly used in dike construction. This paper presents a procedure that can detenmine the relatiorrship among the tube size, the pumping pressure, the unit weight of the slurry, and the tensile stress developed in the geotextile during the tube filing. When the tubes are piling up to form the dike, the tubes in the bottom will sustain the load from the weight of the upper ones. A procedure is also developed to calculate the changes of the mechanical and geometrical behavior of the tubes under the load with a similar method. All these approaches have been programmed, which can help dike designers to select the suitable geotextile and determine the profile of the dike. 展开更多
关键词 geotextile tube design dike inflated tensile force
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LA-ICP-MS U-Pb Zircon Geochronology of Basic Dikes within Maxianshan Rock Group in the Central Qilian Orogenic Belt and Its Tectonic Implications 认领 引用 被引量：3
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作者 何世平 王洪亮 +4 位作者 陈隽璐 徐学义 张宏飞 任光明 余吉远 《Journal of China University of Geosciences》 2007年第1期19-29,共11页
A large number of basic dikes, which indicate an important tectonic-magmatic event in the eastern part of the Central Qilian （祁连） orogenic belt, were found from Maxianshan （马衔山） rock group, Yongjing （永靖） ... A large number of basic dikes, which indicate an important tectonic-magmatic event in the eastern part of the Central Qilian （祁连） orogenic belt, were found from Maxianshan （马衔山） rock group, Yongjing （永靖） county, Gansu （甘肃） Province, China. According to the research on the characteristics of geology and petrology, the basic dike swarms, widely intruded in Maxianshan rock group, are divided into two phases by the authors. U-Pb isotope of zircons from the basic dikes above two phases is separately determined by LA-ICP-MS in the Key Laboratory of Continental Dynamics of Northwest University, China and the causes of formation of the zircons are studied using CL images. The formation age of the earlier phase of metagabbro dikes is （441.1±1.4） Ma （corresponding to the early stage of Early Silurian）, and the age of the main metamorphic period is （414.3±1.2） Ma （corresponding to the early stage of Early Devonian）. The formation age of the later phase of diabase dike swarms is （434±1.0） Ma （corresponding to the late stage of Early Silurian）. The cap- tured-zircons from diabase dike swarms saved some information of material interfusion by Maxianshan rock group （^207pb/206pb apparent ages are （2 325±3）-（2 573 ±6） Ma）, and some zircons from diabase dike swarms also saved impacted information by tectonic thermal event during the late period of Caledonian movement （^206pb/^238U apparent ages are （400±2）-（429±2） Ma）. By combining the results of the related studies, the basic dikes within Maxianshan rock group were considered to be formed in the transfer period, from subductional orogeny towards collisional orogeny, which represents geological records of NW-SE extension during regional NE-SW towards intense compression in the Central Qilian block. 展开更多
关键词 Maxianshan rock group basic dike swarms zircon LA-ICP-MS U-Pb geochronology,Silurian extension
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Variation of hydraulic parameters with different wing of a T-shape spur dike in bend channels 认领 引用 被引量：2
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作者 Mohammad Vaghefi Arash Ahmadi Behroz Faraji 《Journal of Central South University》 SCIE EI CAS CSCD 2018年第3期671-680,共10页
In the present research,by using a numerical model,some analyses were performed on flows around a T-shape spur dike and a support structure located at its upstream under different wing to length ratios of T-shape spur... In the present research,by using a numerical model,some analyses were performed on flows around a T-shape spur dike and a support structure located at its upstream under different wing to length ratios of T-shape spur dike in the order of 0.25,0.50,0.75 and 1.00.In order to verify numerical model,physical model data were used in presence of a single T shape spur dike.Results from numerical model are desirably in agreement with those of physical one because the regression between both data is 0.86 up to 0.92.In this research,all hydraulic parameters of flows,streamlines and dimensions of flow separation zones were studied in order to select the most practical model.Increased W/L results in 7%–12%increase in the length of flow separation zone and in 2%increase in the width of this zone compared to W/L=0.25. 展开更多
关键词 numerical model wing of T-shape spur dike support structure flow pattern
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