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基于势流理论,对半圆型开孔潜堤在波浪作用下的水动力特性进行解析研究。利用多极子展开法和分离变量法,在极坐标系下建立半圆型开孔潜堤内外流场的速度势表达式,通过迭代匹配求解开孔板处的非线性压力损失边界条件,确定速度势表示式中的展开系数,计算反射系数、透射系数、波浪力等水动力参数。将水动力参数的解析计算结果与分区边界元法的数值计算结果进行对比,符合良好。通过算例分析,明确了潜堤半径、开孔率等对反射系数,透射系数和波浪力的影响规律。研究结果可为半圆型防波堤的工程设计提供有效指导。 相似文献
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新型开孔工字板组合式防波堤波浪力特性试验研究 总被引：1，自引：1，他引：0
开孔工字板组合式防波堤是基于透空板式防波堤的一种新型结构形式,具有自重轻、材料省的特点。为充分了解新型开孔组合式防波堤的受力特性,基于室内水槽物理模型试验,测量新型开孔工字板组合式防波堤上的波压力与结构总力,研究相对波高H/d、相对波长L/B对该新型防波堤结构表面压力的影响,讨论了该新型防波堤所受波浪力荷载与相对波高H/d、相对波长L/B的关系。结果表明,相对波高H/d是决定新型防波堤结构表面波压力和结构总力的主要影响因素。该新型防波堤结构波浪力荷载以垂直方向受力为主,新型防波堤结构所受竖向总力远大于水平总力,最大可达到15倍。新型防波堤水平总力随相对波长L/B先增大后趋于稳定。相对波长L/B=3.617是防波堤结构水平总力变化幅度的分界点。 相似文献
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《海洋工程》2001,(4)
自由申请项目5 0 1790 0 1天然河流大尺度紊动结构研究 2 1万元 ,长江科学院 卢金友5 0 1790 0 2碾压砼坝诱导缝断面等效强度研究 2 0万元 ,大连理工 吴智敏5 0 1790 0 3半圆型防波堤前海冰的破碎的堆积过程 2 0万元 ,大连理工 李志军5 0 1790 0 4二维和三维随机波浪对半圆型防波堤作用的对比研究 2 0万元 ,大连理工 张宁川5 0 1790 0 5波浪对低反射防波堤作用非线性数值模式的研究 2 0万元 ,大连理工 孙大鹏5 0 1790 0 6复杂应力状态下土的本构模型及其在海床动力学应用 2 5万元 ,大连理工 栾茂田5 0 1790 0 7土基体形变光纤传感监测… 相似文献
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斜搜式防波堤港内一侧为直立式码头的结构型式在我国已多见使用。为了减小波浪穿过堤面和堤心后对直立式码头产生的波压力,从而减小防波堤和码头结构的断面,本文试验研究了几种■荷措施。试验结果表明,设置透空导流排水孔的直墙上的波压力显著地减小。 相似文献
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透空格栅板式防波堤是一种新型防波堤结构,为了促进该结构在实际工程中的应用,论文通过模型试验研究其所受波浪点压力和波浪总力的特征。试验结果表明,在规则波作用下,下层水平格栅板所受波浪点压力较上层水平格栅板大,且防波堤中前端波浪点压力分布不规律;相对板宽B/L对该防波堤所受波浪总力的影响较大,相对板间距S/h对其整体稳定性的影响次之,而相对波高H/h主要影响该防波堤的垂向受力;此外,当上层水平格栅板与静水面齐平且孔隙率相对较大时,该防波堤所受波浪总力最小,对其整体稳定性最有利。 相似文献
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在圆筒形防波堤和V形防波堤的基础上,结合离岸堤后形成V形和半圆形连续出现的韵律海岸的地貌平面形态特点,提出一种前墙为连续的半圆筒形防波堤形式。通过在波浪水槽内进行规则波物理模型试验,探究这一新型防波堤的波压力分布规律及波高、周期、水深等因素对波压力的影响。将试验结果与海港水文公式和合田良实公式计算的理论值对比分析,给出了以合田良实公式的折减系数来拟合新型弧形防波堤波浪总水平力的计算公式。结果表明:新型弧形防波堤上的波压力随波高、周期的增大而增大,其水平波浪总力比同等尺度直墙少10%左右。 相似文献
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防波堤是港工建筑物中的一个重要组成部分,主要作用为保护港湾免受波浪、冰、沙等海洋动力因素的侵袭.综合以往的相关文献,对于防波堤断面破坏形式,如滑移、倾覆、地基滑动等有了非常充分的研究,可以定量计算出其损坏程度.而对于防波堤平面形态的损坏,如蛇行破坏等,只是较深入研究了失效机理,并没有一个能够定量计算其后果的模型.本文第一部分将期望滑移量模型和绕射模型结合,建立了计算半无限长沉箱式防波堤在使用期限内蛇行破坏程度的模型.第二部分则利用实测的波浪数据设计并计算了一个沉箱式防波堤实例.结果表明,各个堤段的期望滑移量呈现出一定周期性变化的规律,堤头附近区域的滑移量远大于较远的堤段,这对于防波堤施工过程中的堤头防护具有参考价值.本文为建立防波堤平面形态损坏定量计算模型提供了一种思路. 相似文献
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回顾了日本防波堤建造的历史，根据波浪力和防波堤稳定性讨论了当今混合式防波堤的设计方法。现在日本的混合式防波堤的设计技术是上来该领域经验和实际研究的鼎盛时期。对于混合式防波堤的绝大部分情况，能够精确地计算出设计波浪力的Ｇｏｄａ公式成了防波堤设计的极好工具，在某些情况下，由于波施于皮波堤上部直墙断面上的冲击压力非常大，因此在进行防波堤设计时必须予以考虑。要采用能够消散波浪力的混凝土块体覆盖在混合式防波 相似文献
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Arne Schnack-Friedrichsen Angela M. Davis Jim D. Bennell Dei G. Huws 《Marine Georesources & Geotechnology》2001,19(4):221-243
The interdependence between the seismo-acoustic properties of a marine sediment and its geotechnical/physical parameters has been known for many years, and it has been postulated that this should allow the extraction of geotechnical information from seismic data. Though in the literature many correlations have been published for the surficial layer, there is a lack of information for greater sediment depths. In this article, a desktop study on a synthetic seafloor model illustrates how the application of published near-surface prediction equations to subsurface sediments (up to several tens of meters burial depth) can lead to spurious predictions. To test this further, acoustic and geotechnical properties were measured on a number of sediment core samples, some of which were subjected to loading in acoustically-equipped consolidation cells (oedometers) to simulate greater burial depth conditions. For low effective pressures (representing small burial depths extending to around 10 meters subsurface), the general applicability of established relationships was confirmed: the prediction of porosity, bulk density, and mean grain size from acoustic velocity and impedance appears generally possible for the investigated sedimentary environments. As effective pressure increases through, the observed relationships deviate more and more from the established ones for the near-surface area. For the samples tested in this study, in some instances increasing pressure even resulted in decreasing velocities. There are several possible explanations for this abnormal behavior, including the presence of gas, overconsolidation, or bimodal grain size distribution. The results indicate that an appropriate depth correction must be introduced into the published prediction equations in order to obtain reliable estimates of physical sediment properties for greater subsurface depths. 相似文献
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Shigehisa Nakamura 《Marine Geodesy》2000,23(1):55-61
Specific properties of the interannual sea level variations and annual tides in the Northwestern Pacific were studied. Several tide stations were monitored. The monthly mean sea level for the year of 1995 was analyzed at each tide station. A seismic event in 1995, some tectonic activity around the subject area, and the Kuroshio (the oceanic western boundary current) may possibly contaminate results which would have occurred from the astronomical annual tide alone. 相似文献
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The effect of different fixation and storage protocols on the flow cytometric (FCM) simultaneous analysis of bacterioplankton and phytoplankton in coastal seawater samples (Mediterranean coastal lagoons) was investigated. FCM measurements (cell number, fluorescence and scatter characteristics) were obtained through DAPI staining. Three fixatives [glutaraldehyde (GA), formaldehyde (FA) and paraformaldehyde (PFA)] and two storage (3 months duration) methods (5 °C and −196 °C) were tested. Two dominant populations were detected in studied samples: bacteria and eukaryotic picophytoplankton. Adding fixatives (2% final concentration) appears necessary to obtain FCM exhaustive counts of all the bacteria and phytoplanktonic cells. This was related to the permeation effect of fixatives which allowed a better DAPI staining of the cells. Maximum fluorescence, i.e. optimal staining of the cells was obtained with FA or PFA, and significant lower fluorescences with GA. Fixed samples stored at 5 °C induced rapid cell loss. Only storage in liquid nitrogen of samples fixed with FA or PFA, allows mid-term (≥4 months) preservation of bacteria or picophytoplankton cell numbers, and limited evolution of DAPI-induced fluorescence and scatter characteristics. 相似文献
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《海洋学报(英文版)》2014,(9):F0003-F0003
<正>Acta Oceanologica Sinica(AOS)is a comprehensive academic journal edited by the Editorial Committee of Acta Oceanologica Sinica and is designed to provide a forum for important research papers of the marine scientific community which reflect the information on a worldwide basis.The journal publishes scholarly papers on marine science and technology,including physics,chemistry,biology, 相似文献
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The relationship between the flux of exotic benthic foraminiferal tests (i.e. tests which are supplied from open-sea sources alone) in a tidal inlet and that of bulk sediment was analysed, which can be expressed as two first-order linear equations. According to this relationship, in order to determine net sediment transport directions in the entrance, the test concentration in surficial sediments of the tidal basin can be compared against a ‘ critical level ’. The critical level is determined for the conditions that no net transport of bulk sediment is present within the entrance. If the observed concentration (averaged over the tidal basin) is higher than the simulated critical level, then the net sediment transport is directed to landward. This method is applied to the analysis of net sand transport at Christchurch Harbour, a tidal inlet system located in southern England. In this investigation, concentrations of exotic foraminiferal tests in the surficial sediments of the tidal basin and ebb tidal delta area were obtained from the analysis of sea-bed sediment samples. A series of probable critical levels were calculated based upon the data sets with regard to: (1) sediment discharge from the rivers; (2) magnitude of sediment discharge within the entrance during the ebb; (3) the test concentration outside the harbour; (4) the thickness of the moving layer; and (5) two parameters associated with dispersive processes. The results show that the concentration in the tidal basin sediment is higher than a number of simulated critical concentrations for representative cases. Consequently, the high level of the concentration of exotic benthic foraminiferal tests within the harbour should be explained as a result of landward net transport of sands within the entrance. 相似文献
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Coastal inundation associated with extreme sea levels is the main factor which leads to the loss of life and property whenever a severe tropical cyclonic storm hits the Indian coasts. The Andhra and Orissa coasts are most vulnerable for coastal inundation due to extreme rise in sea levels associated with tropical cyclones. Loss of life may be minimized if extreme sea levels and associated coastal flooding is predicted well in advance. Keeping this in view, location specific coastal inundation models are developed and applied for the Andhra and Orissa coasts of India. Several numerical experiments are carried out using the data of past severe cyclones that struck these regions. The simulated inland inundation distances are found to be in general agreement with the reported flooding. 相似文献
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Hoi-Soo Jung Kap-Sik Jeong Yong-Shik Chu Sung-Hyun Park Ki-Hyune Kim 《Marine Georesources & Geotechnology》2001,19(3):181-195
Grain size and water content in box-core sediments from the Clarion-Clipperton fracture zone (C-C zone) in the northeast equatorial Pacific were analyzed in detail to understand the downcore variations across a hiatus between Quaternary and Tertiary layers. Grain-size distributions in the topmost core sediments show two modes: a coarse mode (peaked at 50 μm) and a fine mode (at 2-25 μm). The coarse mode disappears gradually with depth accompanied by the dissolution of siliceous fossil tests, whereas the fine mode coarsens due to the formation of authigenic minerals. Water content increases abruptly across a color boundary between an upper pale brown layer and a lower dark brown layer that is the hiatus between Quaternary and Tertiary layers. Abundant smectites and microvoid molds, which are created by the prolonged fossil dissolution in the underlying sediment, are attributed for the abrupt downcore variation of water content. Overall variations in grain size and water content in the topmost core sediments in the western C-C zone are possibly constrained by the dissolution of biogenic siliceous fossils. Variations in geotechnical properties related to these changes must be considered in the design of nodule collectors. 相似文献
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Shigehisa Nakamura 《Marine Geodesy》2001,24(1):27-33
This article concerns an interrelation between the sea levels and the western boundary flow near a tectonic boundary in a local zone in the Northwestern Pacific. In this zone, sea level variations at stations located on the coast facing the Pacific are studied to find the interrelation between variations of the Kurosio flow as an index of the distance of the flow axis off a specific coast. The result is discussed after data processing of the monthly means of the sea levels, and a notice is taken of variations caused by active crustal upheavals during a seismic event, a local earthquake. 相似文献