基于解析解的长江口南港悬沙侧向捕集特征分析     

杨忠勇  王钟  程和琴  郭兴杰  曹振轶 《海洋学报》2017,39(5):22-32

为探讨长江口南港的水动力结构及悬沙侧向输运特征,本文从解析解的角度构建了潮汐河口水沙输运数学模型,并将其应用到长江口南港某横断面上。南港水动力主控于半日潮流,余流主要由陆相径流及本地非线性对流项驱动,悬沙分布上北侧副槽远大于南侧主槽,水沙分布的计算结果与实测结果在结构上基本一致。通过输沙函数进一步分析表明,潮流输沙和余流输沙是南港侧向输沙函数的两个主要部分。南港中强劲径流削弱了涨潮流,增强了落潮流,使得向河槽南侧的涨潮流输沙小于向河槽北侧的落潮流输沙,潮流输沙指向河槽北侧。径流驱动的南港侧向余流在涨潮流方向上为一逆时针环流结构,余流输沙指向河槽北侧。扩散输沙指向南侧主槽,因其总是指向悬沙浓度梯度的负方向。在各输沙因子的综合作用下,南港中大量悬沙捕集于河槽北侧,使得河槽北部底层潮平均含沙量值达到最大值。  相似文献   

Simulating bed evolution following the Barlin Dam (Taiwan,China) failure with implications for sediment dynamics modeling of dam removal     

《国际泥沙研究》2016,(4):299-310

The failure of the Barlin Dam in Taiwan, China offers an important case study for evaluating concepts in modeling the rapid erosion and channel recovery following intentional and unplanned dam removals. We present a modeling effort that applied a 1D and quasi-2D uncoupled hydraulics and sediment model (NETSTARS) to evaluate how discretization and parameterization influence thefitofbed elevationpredic-tions to observations following dam failure. Our analysis evaluated the model sensitivity to sediment transport function, active layer thickness, and number of stream tubes used to define the cross-section. Results indicate that a) the model is more sensitive to active layer thickness and sediment transport function than to the number of stream tubes, b) development of dam removal models are likely to benefit from varying the active layer thickness in time, and c) increased lateral discretization does not appear to improve model fit in the steep and rapidly changing river environment at our site. We conclude with discussion on differences between, identifying the need for, and general use of 1D, quasi-2D, and fully 2D models in dam removal and failure analysis.  相似文献   

An experimental study of sediment transport in channel confluences     

《国际泥沙研究》2016,(1):87-96

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渤海海峡跨海通道工程区地震危险性分析   总被引：2，自引：1，他引：1  

祁嘉翔  纪洪广  彭华  李焕君 《地质力学学报》2013,19(1):93-103

研究渤海海峡地区区域历史地震时空分布特征,分析渤海海峡地区的地震发生位置及其发震规律,论述历史地震对工程场地的影响,为渤海海峡跨海通道的选址提供依据,使选址时尽量避开活动断层以减少地震对跨海通道的影响,增加评判工程稳定性的因子,使评判结论更加可靠。  相似文献   

Quantitative assessment of dissolved radiotracers in the English Channel: Sources, average impact of la Hague reprocessing plant and conservative behaviour (1983, 1986, 1988, 1994)     

P. Bailly du Bois  P. Guguniat 《Continental Shelf Research》1999,19(15-16)

Knowledge of long-term movements of water-masses in the English Channel has been substantially improved using hydrodynamic modelling coupled with radio-tracers studies; nevertheless, the precision of results so obtained is still largely dependent on measurement precision. New tools are now available to make more accurate determinations of radio-tracer distribution: (1) Repositioning of station locations at the same tide reference-time, giving a homogeneous spatial data set, coupled with the possibility of interpolating and quantifying the amounts of dissolved radioactivity flowing through the English Channel; (2) the first measurements of tritium (³H) in seawater on a large scale in the English Channel demonstrate that this fully conservative radionuclide is a clearly identifiable marker of industrial releases; (3) recent campaigns carried out during the FLUXMANCHE II CCE (1994) programme show the general distribution of dissolved radionuclides ¹³⁷Cs, ¹³⁴Cs, ⁶⁰Co, ¹²⁵Sb, ¹⁰⁶Ru and ³H in the English Channel and the Irish Sea; and (4) the re-utilisation of data from previous campaigns (1983, 1986, 1988) provides indications, at any given location in the English Channel, about the average dilution and distribution of releases derived from the La Hague reprocessing plant. Excesses and losses of radionuclides are now quantified with respect to known source terms; estimates of losses are provided for non-conservative radionuclides, while an excess of ¹³⁷Cs was observed in the English Channel during the period 1983–1994. This excess, which has the same order of magnitude as the quantities released from La Hague plant in the English Channel, could be explained by about 1% of the Sellafield reprocessing plant releases entering the Channel. These results confirm and give a more detailed picture of the previously known distribution of water masses in the English Channel. They lead to clear information about transit times and dilution at this scale, and provide directly comparable data for the validation of hydrodynamic models.  相似文献   

Geological information from telecommunications cable route surveys of the continental shelf     

J. Noad  A. Crosby 《Marine Georesources & Geotechnology》2013,31(4):323-333

Several burial assessment surveys using a seabed plough have been carried out along routes on the United Kingdom continental shelf to assess their potential for cable burial. Detailed information on sediment thicknesses and characteristics within the top meter of the seabed was collected using a survey tool called the Plough Surveyor. Geophysical surveys along these routes have enabled correlation with the plough data. Results include the range of tensions, tension trace characteristics, and typical penetration, and these have been correlated with seabed types and thickness of sediment.  相似文献   

‘Universal’ recession curves and their geomorphological interpretation     

《Advances in water resources》2014

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基于NMM随钻电磁波传输信道特性分析   总被引：1，自引：0，他引：1       下载免费PDF全文

范业活  李威  聂在平  杨志强  孙向阳 《地球物理学报》2016,59(3):1125-1130

基于数值模式匹配法(NMM)与源等效原理,建立了随钻电磁波传输理论模型,可以同时考虑介质的径向和轴向非均质性,便于分析套管、泥浆、高导层、高阻层对信号传输的影响.通过理论计算结果与试验结果对比,验证了理论模型的正确性.在此基础上对地层电阻率、工作频率、套管、泥浆、钻柱导电性、高导层和高阻层对信号传输的影响进行了计算分析.  相似文献   

美国国家公园志愿者服务及机制——以海峡群岛国家公园为例     

王辉  刘小宇  郭建科  孙才志 《地理研究》2016,35(6):1193-1202

具有百余年历史的美国国家公园志愿者服务已成为美国国家公园管理的重要部分,志愿者服务有效实现了美国国家公园的全民管理思路。通过实地考察和访谈记录梳理,就国家公园志愿者服务的相关概念、服务动机、服务决策、服务内容、服务支持和服务机制深入剖析,从庞大有序的服务系统、管理与运行、功能实现三方面分析国家公园志愿者服务机制;提炼出美国国家公园志愿者服务的四个支持：宣传支持、技术支持、学习支持和立法支持。并以美国海峡群岛国家公园为例进行论证。最后提出国家公园志愿者服务和中国国家公园志愿服务尚需研究的诸多内容,任重而道远。  相似文献   

槽波层析成像方法在煤田勘探中的应用——以河南义马矿区为例   总被引：9，自引：4，他引：5       下载免费PDF全文

王伟  高星  李松营  乐勇  胡国泽  历玉英 《地球物理学报》2012,55(3):1054-1062

在地下煤田的开发中,工作面内的小构造、异常体、煤层厚度变化等是需要解决的关键问题,而槽波探测则为这些问题的解决提供了重要的物探方法.本文对河南义马矿区11061工作面进行槽波透射法测量,在巷道显示的煤层厚度变化为1.5~8 m,从理论频散曲线分析速度与厚度关系,确定125 Hz频率槽波主要用于观测厚度约为2~5 m的煤层厚度变化;有效提取了684个频散曲线,并分别拾取了125 Hz时槽波群速度与走时,采用走时层析成像方法获得工作面内煤层速度、厚度以及高应力区分布特征,回采验证了结果的正确性.  相似文献