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海底沉积物声学物理力学性质聚类分析研究 总被引：1，自引：1，他引：0
Stoll、Hamilton等分别从理论和实测方面出发研究海底沉积物声学与物理力学性质关系,这两类研究都是将声学性质作为独立性质从沉积物的物理性质中提取出来,以两者作为因果关系进行研究,割裂了其内在统一性.本文不试图建立声学与物理力学性质的经验方程,而是综合考虑海底沉积物声学、物理力学性质,对南海大陆坡和人陆架沉积物进行聚类研究,分析南海海底沉积物共有的性质.研究表明聚类分析方法为海底沉积物性质研究提供了一种有效的分类手段,通过聚类,得出如下结论:(1)声速与孔隙度、密度等物理力学性质存在着明显的单调相关性,可以通过某些物理力学参数来预报沉积物的声速,同时可以通过测量沉积物声速反演沉积物的某些物理力学参数;(2)海底沉积物的声速和地文单元、沉积物的颗粒成份组成有关;(3)火陆坡黏土质粉砂、粉砂、砂质粉砂和大陆架粉砂、砂质粉砂、粉砂质砂的压缩波速依次增大,切变波速依次减小;(4)海底沉积物声学与物理力学性质聚类分析研究,可以作为海底沉积物的声学探测的参考依据. 相似文献
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海底表层沉积物具有多相、多颗粒、多形态的组成结构，导致其声学特性复杂多样。通过分析压缩波速度和切变波速度特性的研究现状，指出有待于解决的科学问题和关键技术问题。在分析国内外有关海底沉积层声速特性研究基础上，提出采取系统、可控的实验测量手段解决当前测量存在的4点问题。综合分析了压缩波速度和切变波速度存在的统计回归关系和理论分析关系，探讨了当前地声反演、采样样品声学测量、原位声学测量3种方法存在的测量尺度、测量频率、测量状态等的差异，探讨建立不同测量方法和测量技术对测量结果进行统一性解释的方法，从而获得不同类型、不同区域的海底表层沉积物真实的声速特性。最后，从实验室声学测量、物理力学参数测量、流固耦合特性分析、原位测量及海底监测、采样测量与原位测量的误差分析及校正、海底大纵深声学测量6个方面提出技术需求，为提高声学探测海洋和海底的精度服务，推动海洋声学探测和海洋工程发展。 相似文献
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通过对海洋沉积物声速及其物理-力学参数相关性的初步分析和研究,可以找到估算沉积物压缩波速Vp和切变波速Vs的经验式,最终为海底沉积物的性质进行声学遥测、为发展海底参数声遥感服务。本文给出了7个较为理想的回归方程。沉积物的物理参数与Vp有密切的关系;力学参数对Vs的预报有较大的作用。若增加物理参数作为修正项,其效果更佳。 相似文献
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双频测深仪在海底浅层物质分类中的应用 总被引：1，自引：0，他引：1
双频测深仪在进行水深地形测量的同时，通过对声波透射信号的分析，可以判别海底浅层物质类型属性。介绍了声波透射地层的物理特性和测量方法，列举了工程测量中双频测深仪的模拟记录和数字记录的图像，对典型的悬浮淤泥、软泥、沙质和基岩的浅层资料进行了分析，并比较了地质取样资料，说明使用双频测深仪判别海底浅层物质类型是可行的。 相似文献
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报道了南海浅海海底沉积物的声衰减性质。给出了测量和计算海底沉积物声衰减的方法。分析讨论了不同频率下的声衰减以及与若干个海底沉积物物理参数的关系,结果表明,同一类型沉积物在高频段时的声衰减要比低频段的声衰减大;同一频段下粗颗粒沉积物的声衰减要比细颗粒的声衰减大;北部湾海底浅层沉积物声衰减在低频100kHz下为80~150dB/m,在高频1MHz下为150~360dB/m;海南岛南部外海海底浅层沉积物声衰减在低频下为66~160dB/m,在高频1MHz下为190~350dB/m;高频段的数据与台湾海峡北部海底表层沉积物声衰减测量分析数据比较接近,而低频段的数据与台湾海峡北部海底表层沉积物声衰减测量分析数据有较大的差别。 相似文献
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南海北部大陆架海底沉积物物理性质研究 总被引：6，自引：0，他引：6
用物理(声学的、工程地质的、扫描电子显微镜)等技术方法，综合分析了沉积物结构特征和工程力学性质，研究了颗粒接触、堆垒、孔隙等现象与物理性质之间的关系，得出了沉积物声学物理参数和应力一应变性质之间的关系。结果表明，南海北部大陆架海底沉积物有6种结构类型，其中混合接触结构类型的沉积物具有较高的抗压强度和声速，浅层海底存在着高、低声速分层的中尺度结构。 相似文献
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分析研究了南海北部大陆架西南缘的海南岛东南外海海底沉积物声学物理特性,在多个航次中进行了海底沉积层取样、海水CTD测量、浅地层及旁侧声呐扫测等工作.在实验室里对沉积物样品进行声学参数、沉积学基本参数、物理力学参数和14C年龄测试等分析.根据多尔特曼公式求解出弹性模量、体积弹性模量、压缩系数、切变模量、泊松比和拉梅常数等六项沉积物弹性参数.分析结果表明在该海区海底沉积物的压缩波速为1.474~1.700 m/s,在不同的海区内有高低声速两类性质的沉积物分布;沉积物的切变波速为150~600 m/s;沉积物在100 kHz的声衰减为35~260 dB/m;沉积物的密度为1.4~2.0 g/cm3;沉积物的孔隙度为42%~88%. 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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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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《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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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
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This study tests the hypothesis that the in situ void ratio of surficial marine sediments may be predicted from shear wave velocity-depth data with a reliability equal to that of other methods currently available. Shear wave velocity is fundamentally controlled by the number of grain-to-grain contacts per unit volume of material and by the effective stress across those contacts. In this study, three previously established empirical formulae are used to predict void ratio from velocity-depth data. Field data were acquired along a transect off the northern Californian coast across which water depth increased from 35 to 70 m and seafloor sediment type varied from sand to silty-sand, respectively. A towed seafloor sled device was used to collect shear wave refraction data, and a marked, systematic decrease in velocity was observed along the line, ranging from 35-70 m/s for the coarse, near-shore material to 25-40 m/s for the finer, offshore deposits. Void ratios predicted from these velocities were compared with data measured directly from box-core samples. Of the formulae used for prediction, two agree remarkably well with the control data. Both predicted and control values increase from 0.6-0.8 for the sandy material to 1.1-1.5 for the silty-sand. Thus, this study does not disprove the hypothesis set and demonstrates the potential of field shear wave velocity-depth data as a means of delineating spatial variation in void ratio for surficial marine sediments in a remote, nondestructive manner. 相似文献
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Particulate samples were collected from the Changjiang river system during a flood period, in May 1997, and POC, stable isotope and lipids associated with particles were examined. Results showed the decrease (0.84% ～ 1.88%) of organic carbon content from the upper reaches to the estuary.δ13C values of particulate organic carbon was in the range of -24.9×10-3 to -26.6×10-3, which were close to the isotopic signature of continental C3 vegetation. Total particulate n-alkanes concentrations varied from 1.4 to 10.1μg/dm3,or from 23.7 to 107μg/g of total suspended matter. Fatty acids were present in all the samples, from 1.4 to 5.4μg/dm3, with saturated and unsaturated straight-chain and branched compounds in the carbon number range from C12 to C30. Both δ13C and the ratio of carbon content to nitrogen content indicate the predominance of terrestrial inputs (soil organic matter) among the particles. The biomarker approach has been used to identify the relative portion of terrigenous and autochthonous fraction in the particulate samples. The distribution of fatty acids suggests a striking phytoplanktonic and microbial signal in most particle samples. The terrestrial alkanes are used to estimate the contribution of terrestrial inputs along the mainstream. 相似文献