Investigation on the Effect of Geometrical and Geotechnical Parameters on Elongated Offshore Piles Using Fuzzy Inference Systems     

Ali AMINFAR  Alireza MOJTAHEDI  Hamid AHMADI  Mohammad Hossain AMINFAR 《海洋工程》2017,31(3):378-388

Among numerous offshore structures used in oil extraction, jacket platforms are still the most favorable ones in shallow waters. In such structures, log piles are used to pin the substructure of the platform to the seabed. The pile’s geometrical and geotechnical properties are considered as the main parameters in designing these structures. In this study, ANSYS was used as the FE modeling software to study the geometrical and geotechnical properties of the offshore piles and their effects on supporting jacket platforms. For this purpose, the FE analysis has been done to provide the preliminary data for the fuzzy-logic post-process. The resulting data were implemented to create Fuzzy Inference System (FIS) classifications. The resultant data of the sensitivity analysis suggested that the orientation degree is the main factor in the pile’s geometrical behavior because piles which had the optimal operational degree of about 5° are more sustained. Finally, the results showed that the related fuzzified data supported the FE model and provided an insight for extended offshore pile designs.  相似文献   

西沙海域南部多边形断层的发现及其分布特征与控制因素     

杨涛涛  吕福亮  王彬  杨志力  李丽  张强 《海相油气地质》2017,22(1)

根据新采集的三维地震资料,在西沙海域南部发现了多边形断层,其发育分布具有层控特征明显、在富泥地层中发育、多方位走向、纵向断距小、平面延伸长度小且形态为不规则多边形等特征。由于研究区东西两侧应力条件的差异,导致多边形断层发育特征的差异明显。通过对多边形断层发育控制因素的分析,认为地层岩性(特别是西沙海域上构造层的远源细粒沉积物)是其发育的主控因素之一,同时水道砂岩、成岩作用及构造作用等也是影响其发育分布的因素。多边形断层可以作为流体运移的通道,它与下部构造断层连接可将深部烃源岩中的油气运移到上部储层中聚集,或继续向上运移到浅部地层中形成天然气水合物。  相似文献   

中国近海海表温度对气候变暖及暂缓的显著响应     

谭红建  蔡榕硕  黄荣辉 《气候变化研究进展》2016,12(6):500-507

基于多套全球海温再分析数据和2种线性趋势分析方法,评估了1958-2014年中国近海海表温度（SST）的变化及其对全球气候变化的响应特征,并与全球平均地表温度特别是与若干重要海区的SST做了比较。研究表明：在全球变暖的显著加速期（1980年代和1990年代）,中国近海区域年平均SST表现出更快速的升温特征,其速率达0.60℃/10a,是同期全球平均升温速率的5倍以上;在变暖暂缓期（1998-2014年）,中国近海SST出现显著的下降趋势。研究还表明,中国近海区域SST的年代际变化与太平洋年代际涛动（PDO）的位相转换一致,前者SST的快速上升（下降）期与PDO正（负）位相最大值的时期相对应,PDO可能是通过东亚季风和黑潮影响中国近海SST的年代际变化。  相似文献   

浅海区域Topex/Poseidon测高卫星数据波形重构方法   总被引：6，自引：2，他引：4       下载免费PDF全文

鲍李峰  陆洋  许厚泽 《地球物理学报》2004,47(2):216-221

根据测高卫星返回波形的特征,给出了由Topex/Poseidon卫星波形数据进行波形重构的方法,并采用函数逼近算法确定波形重构改正量,进而改善测高卫星近海岸海面高观测值的精度.在中国南海区域计算了四圈T/P测高卫星经过波形重构后的海面高数据.近海岸海面高数据与相近时刻验潮站数据相比,精度比波形重构前有了很大提高,证明该方法的有效性.  相似文献   

A new look at the phenomenon of offshore pile plugging     

Samuel G. Paikowsky  Robert V. Whitman  Mohsen M. Baligh 《Marine Georesources & Geotechnology》2013,31(3):213-230

Abstract

Open‐pipe piles are widely used for offshore structures. During the initial stage of installation, soil enters the pile at a rate equal to the pile penetration. As penetration continues, the inner soil cylinder may develop sufficient frictional resistance to prevent further soil intrusion, causing the pile to become plugged. The open‐ended pile then assumes the penetration characteristics of a closed‐ended pile. The mode of pile penetration significantly alters the soil‐pile interaction during and after installation. This affects the ultimate static bearing capacity (mainly in granular materials), the time‐dependent pile capacity (in clays), and the dynamic behavior and analysis of the piles.

Following a summary demonstrating the effects of pile plugging, a review of the common view of offshore pile plugging is undertaken. The interpretation of plugging by referring to the average plug length has led to the erroneous conclusion that in most piles significant plugging action does not occur.

Establishment of an analogy between soil samplers and open‐ended piles enabled correct identification of plugging by referring to the incremental changes in plug length. Examination of case histories of plugging of offshore piles revealed that beyond a certain penetration depth‐to‐diameter ratio, most piles are plugged.  相似文献   

Offshore wind capital cost estimation in the U.S. Outer Continental Shelf—A reference class approach     

Mark J. Kaiser  Brian Snyder 《Marine Policy》2012

Offshore wind power developed rapidly in Northern Europe in the first decade of the 21st century and is expected to spread to Southern Europe, North America and Asia before 2020. To date, no projects have been built offshore North America because of the high development costs and economic risk and uncertain profitability. The purpose of this paper is to review the development cost of constructing offshore wind farms to inform the U.S. market. The capital expenditures of a reference class of 18 European wind farms constructed after 2005 with monopile foundations are normalized to proxy U.S. capital cost. Regression models are developed to investigate the physical features that influence expenditures. U.S. capital costs are expected to range between $4 and $5.6 million/MW for projects built between 2012 and 2015. Capital costs increase with increasing water depth and steel prices. For most farm components, capital expenditures are expected to be similar in Europe and the U.S., but the installation markets differ and this may impact the reliability of the reference class approach.  相似文献   

一种适用于石油平台的有缆潜标系统的设计与布放方法   总被引：1，自引：0，他引：1  

倪佐涛  姜静波  徐永平  李思忍  涂登志 《海洋科学》2012,36(12):81-83

针对石油平台上的海洋环境动力检测,设计一套有缆潜标系统,并进行现场布放.该设计采用从海底到石油平台垂直布放一根受力钢缆,测量设备和通讯电缆依附于受力钢缆上.布放时采用船舶布放有缆潜标水下部分,平台布放有缆潜标水面以上部分,两部分在水面附近进行连接,调整受力.该设计可以大大降低布放成本,避免有缆潜标系统缠绕平台桩腿等问题,有一定的工程施工参考价值,可以应用于石油平台的有缆潜标布放设计.  相似文献   

Centrifuge modeling of offshore wind foundations under earthquake loading     

《Soil Dynamics and Earthquake Engineering》2015

The construction of large offshore wind turbines in seismic active regions has great demand on the design of foundations. The occurrence of soil liquefaction under seismic motion will affect the stability of the foundations and consequently the operation of the turbines. In this study, a group of earthquake centrifuge tests was performed on wind turbine models with gravity and monopile foundations, respectively, to exam their seismic response. It was found that the seismic behavior of models was quite different in the dry or saturated conditions. Each type of foundation exhibited distinct response to the earthquake loading, especially in the offshore environment. In the supplementary tests, several remediation methods were evaluated in order to mitigate the relatively large lateral displacement of pile foundation (by fixed-end pile and multi-pile foundation) and excessive settlement of gravity foundation (by densification, stone column, and cementation techniques).  相似文献   

Planners to the rescue: Spatial planning facilitating the development of offshore wind energy     

Stephen Jay 《Marine pollution bulletin》2010,60(4):493-499

The development of offshore wind energy has started to take place surprisingly quickly, especially in North European waters. This has taken the wind energy industry out of the territory of planning systems that usually govern the siting of wind farms on land, and into the world of departmental, sectoral regulation of marine activities. Although this has favoured the expansion of offshore wind energy in some respects, evidence suggests that the practice and principles of spatial planning can make an important contribution to the proper consideration of proposals for offshore wind arrays. This is especially so when a strategic planning process is put in place for marine areas, in which offshore wind is treated as part of the overall configuration of marine interests, so that adjustments can be made in the interests of wind energy. The current process of marine planning in the Netherlands is described as an illustration of this.  相似文献   

PBDEs, methoxylated PBDEs and HBCDs in Japanese common squid (Todarodes pacificus) from Korean offshore waters     

Gi Beum Kim  Heather M. Stapleton 《Marine pollution bulletin》2010,60(6):935-940

Little information is available on the levels of brominated compounds found in biota from the Korean Peninsula. In this study, Japanese common squids (Todarodes pacificus) were analyzed for 38 polybrominated diphenyl ethers, two methoxylated polybrominated diphenyl ethers and three stereoisomers of hexabromocyclododecane (α, β, and γ-HBCD) from the east and western coasts of the Korean Peninsula. Among 38 PBDEs, 10 PBDEs were detected and their total concentrations ranged from 21 to 292 ng/g lipid wt with a mean concentration of 108 ng/g lipid wt, while two MeO-BDEs and three isomers of HBCDs were detected in all samples. BDE47 showed the highest residual level, followed by BDE99, 154, 153, 28/33. Concentrations of PBDEs and MeO-BDEs were not significantly different between the both sides of the Korean Peninsula; however, HBCD concentrations were higher levels in the East/Japan Sea than the Yellow Sea, indicating that HBCD sources possibly exist in Japan.  相似文献