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典型海上升压站地震储备承载系数研究 总被引：1，自引：1，他引：0
海上升压站是海上风电场中不可或缺的组成部分,其结构型式与传统的海上油气平台有所差异,完全套用现有抗震分析方法可能使结构设计不经济。由于地质条件特点不同,国外海上风电场鲜有位于高地震烈度区的案例,因此当前有关海上升压站抗震设计的理论和经验也不充分。针对我国首个位于高地震烈度区内的海上升压站,建立精细化有限元模型,利用非线性静力推覆分析方法,并结合敏感性分析结果与工程实际情况给出其地震储备承载系数的合理化取值,为今后典型海上升压站的抗震设计提供参考与借鉴。 相似文献
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为了适应当前的海洋开发需求,海洋工程结构物的大型化已成为必然发展趋势,这使得原有海工建造施工场地的滑道处于临界承载状态,给安全生产带来了巨大隐患。本文针对典型滑道结构,采用有限元参数化建模技术(ANSYS Parametric Design Language,ANSYSAPDL)模拟上部载荷滑块在滑道板上的灵活布置,对滑道强度储备进行分析。研究表明:设计载荷下,滑道板的强度储备较滑道桩体及滑道桩侧土小,滑道强度的控制因素为滑道板强度;改变上部载荷滑块的位置,探索不同位置处滑道极限承载力,提高施工建造过程中滑道利用率。 相似文献
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为了调查深层储油岩体中存在的喜高温微生物，从北海东设得兰海盆锡斯尔海岸之外的石油生产平台上，首次从处理设施上侧井口刚冒出的储油岩体油流中采集了样品．稍后，从美国阿拉斯加北坡普拉德霍湾，恩迪科特和库帕勒克油田33口井中采集到类似样品． 相似文献
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超大型海洋浮式储油系统的风险评估 总被引：6，自引：3，他引：6
对超大型海洋浮式储油系统的危险灾害识别、失效概率计算、失效后果评估、风险准则评定和风险管理决策等几个主要步骤进行了风险分析,计算结果为在设置防坡堤情况下,储油船漂移的概率为2 217×10-6,沉没的概率为6 778×10-8,结构损坏的概率为6 300×10-7,总的经济损失为70万人民币;在未设置防波堤的情况下,储油船漂移的概率为3 167×10-3,沉没的概率为9 683×10-5,结构损坏的概率为9 000×10-4,总的经济损失为9 91亿人民币。结果表明,采取合理的措施,如在储油船系泊地点设置防波堤,以降低风险水平是十分必要的。 相似文献
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浮式石油平台作为一种海上石油生产基地，在海上服役过程中，受到各种恶劣多变的海况影响，易导致模块支墩结构发生失效破坏，使上部模块存在整体倾覆的风险。因此，本文以我国浮式石油平台作业较多的南海海域为例，开展在不同海况下浮式石油平台模块支墩动态力学分析与试验研究。通过有限元仿真软件建立上部模块三维模型，开展支墩结构动态力学分析，根据仿真云图找到了支墩危险部位，并用六自由度平台模拟多种海况进行模型试验，验证仿真的正确性。在此基础上对模块支墩进行安全校核和结构优化。试验与仿真结果表明：支墩危险部位为筋板、肘板处，通过加厚、倒角可有效减小危险部位的应力集中及最大应力值，文中提出的六自由度平台模拟海况的试验方法可用于单模块模型的动态力学分析，研究结果为浮式石油平台上部模块支墩的力学分析和设计建造提供参考。 相似文献
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海洋平台长期暴露在海洋环境当中,因此复杂的海上环境载荷以及爆炸、火灾等偶然载荷作用会对平台的安全造成很大的威胁。安全储备概念的提出就是为了对结构的安全性进行量化评价。对现阶段结构安全储备的研究进行分析和总结,为海洋平台结构安全性的定量分析提供思路,从而能够更合理地提高海洋平台结构的安全储备。首先概述了海洋平台方面安全储备的发展过程。综述了结构安全储备方面的相关概念、分类方式、评价标准以及相关的安全储备性能指标。从确定性研究方法和基于概率的研究方法两方面,对海洋平台安全储备研究现状进行对比和总结,并分别列举了构件层次的安全储备和与海洋平台结构相关的RSR和CMR等安全储备指标及研究方法,并提出了一些关于海洋平台结构安全储备研究的问题和思路。 相似文献
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2008年,中国长三角地区港口原油及成品油吞吐量就已经达2亿吨,随着四大战略石油储备基地的建成和投入使用,长三角地区的石油运输量和储备容量必将呈现不断上升的趋势,我国近海海域面临的石油泄漏风险也在不断提高。2010年,重大海洋溢油事件连续发生,4月22日开始的美国墨西哥湾原油泄漏事件尚未结束,7月16日大连新港海域就发生了规模和影响都较大的原油污染事件,再一次给我们敲响了警钟。 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
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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
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Andrzej Chybicki 《Marine Geodesy》2018,41(1):1-23
Current trends of development of satellite derived bathymetry (SDB) models rely on applying calibration techniques including analytical approaches, neuro-fuzzy systems, regression optimization and others. In most of the cases, the SDB models are calibrated and verified for test sites, that provide favorable conditions for the remote derivation of bathymetry such as high water clarity, homogenous bottom type, low amount of sediment in the water and other factors. In this paper, a novel 3-dimensional geographical weighted regression (3GWR) SDB technique is presented, it binds together methods already presented in other studies, the geographically weighted local regression (GWR) model, with depth dependent inverse optimization. The proposed SDB model was calibrated and verified on a relatively difficult test site of the South Baltic near-shore areas with the use of multispectral observations acquired by a recently launched Sentinel-2 satellite observation system. By conducted experiments, it was shown that the proposed SDB model is capable of obtaining satisfactory results of RMSE ranging from 0.88 to 1.23[m] depending on the observation and can derive bathymetry for depths up to 12m. It was also shown, that the proposed approach may be used operationally, for instance, in the continuous assessment of temporal bathymetry changes, for areas important in the context of ensuring local maritime safety. 相似文献
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N. H. Khadge 《Marine Georesources & Geotechnology》2000,18(3):251-258
As a part of the environmental impact assessment studies, geotechnical properties of sediments were determined in the Central Indian Basin. The undrained shear strength and index properties of the siliceous sediments were determined on 20 box cores of uniform dimension collected from various locations in five preselected sites. The maximum core length encountered was 41 cm and most of the sediments were siliceous oozes consisting of radiolarian or diatomaceous tests. The shear strength measurements revealed that surface sediments deposited in recent times (0-10 cm) have a shear strength of 0-1 kPa; this value increases with depth, reaching 10 kPa at 40 cm deep. Older sediments have greater strength because of compaction. Water content varies in the wide range of 312-577% and decreases with depth. The clay minerals such as smectite and illite are dominant and show some control over water content. Wet density, specific gravity, and porosity do not indicate any notable variation with depth, thereby indicating a uniform, slow rate of sedimentation. The average porosity of sediments is 90.2%, specific gravity 2.18, and wet bulk density 1.12 g/cm 3 . Sediments exhibit medium to high plasticity characteristics, with the average plasticity index varying between 105% and 136%. Preliminary studies on postdisturbance samples showed an increase in natural water content and a decrease in undrained shear strength of sediments in the top 10- to 15-cm layer. 相似文献
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J. N. Pattan Ch. M. Rao A. A. Migdisov S. Colley N. C. Higgs L. Demidenko 《Marine Georesources & Geotechnology》2001,19(3):155-165
The rare earth element (REE) distribution in nine deep-sea ferromanganese nodules and their associated siliceous sediments from the Central Indian Ocean Basin (CIOB) have been studied to elucidate the REE relationship among them. Total REE concentration varies from 398-928 ppm in the nodules and 137-235 ppm in the associated sediments, suggesting two- to four-fold enrichment in the nodules compared to associated sediments. REE of nodules and their associated sediments show a positive correlation, suggesting REE are supplied from a common source such as seawater. The positive correlation between REE of nodules and sediments from the CIOB is contrary to the competitive scavenging of REE between nodules and sediment in the equatorial Pacific Ocean. REEs in the nodules are carried by Fe, P, and Ti, whereas in the sediment they are carried by P and Mn phases. A similar REE fractionation pattern with middle REE enrichment over heavy and light REE in both the nodules and their associated sediment suggest fractionation is independent of REE abundance and their carrier phases. 相似文献
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Lori E. Fenstermacher Gregory B. Crawford Jeffry C. Borgeld Tristan Britt Douglas A. George Meredith A. Klein Neal W. Driscoll Larry A. Mayer 《Marine Georesources & Geotechnology》2001,19(2):135-145
Detailed acoustic surveys of benthic sediments were conducted in July 1995 and September 1998 in the vicinity of Humboldt Bay, California. During these surveys, a band of enhanced acoustic backscatter was observed offshore from the bay entrance, approximately parallel to the isobaths, in water depths ranging from 16-24 m. In order to assess the cause of the increase in backscatter levels, a more comprehensive study was conducted in August and September 1999 using 100 kHz side-scan sonar, bottom grab sampling and underwater video recording. New observations indicated that a dense population of sand dollars ( Dendraster excentricus ) coincided with the enhanced backscatter band. Compared to the two previous acoustic studies, the central section of the band expanded westward by 180 m and the southern section of the band shifted eastward by 160 m, possibly resulting from a change in the biological or physical factors which influence the location and breadth of sand dollars. The relationship between high sand dollar abundance and enhanced acoustic backscatter was further verified in the nearshore region off Samoa Beach California, where a dense, banded population of sand dollars was previously observed. Video footage confirmed the presence of a band of sand dollars, also nominally parallel to the isobaths, in water depths of 8-15 m. A band of enhanced backscatter coincided with the dense sand dollar population. The identification of dense aggregations of sand dollars through enhanced acoustic backscatter could lead to the use of acoustic techniques to study sand dollar distributions and abundance. 相似文献
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Vast reserves of marine minerals are known to occur within the Mexican Exclusive Economic Zone. These reserves include: (1) heavy mineral placers rich in titanium and iron along the coast of San Antonio del Mar, Baja California and the southern States of Oaxaca and Guerrero; (2) phosphorites, which represent the only source for superphosphate fertilizers along the Pacific coast off the Baja California peninsula and the Gulf of Tehuantepec; and (3) manganese oxide deposits in nodule and crusts located adjacent to the Clarion-Clipperton Zone and containing high concentrations of Cu + Ni + Co (up to 1.9%), which are essential for the steel and super-alloy industries. Few but important efforts toward surveying these deposits have been carried out by Mexican and international researchers. Relevant data generated by these investigations are reviewed here and put together in a single document. Adequate knowledge of Mexican mineral resources is essential for the development of management strategies when offshore mining starts during this century. Thus, the review discusses the economics inherent to ocean mining in Mexico, setting baselines for future exploration and development activities in the Mexican Exclusive Economic Zone. 相似文献