An investigation into the lateral loading response of shallow bucket foundations for offshore wind turbines through centrifuge modeling in sand     

《Applied Ocean Research》2019

A shallow suction bucket is a new foundation type for offshore wind turbines. Due to its large size and bulky shape, the bucket and the soil within the bucket do not necessarily deform as a whole. Moreover, limited research has been conducted on the hydrodynamic wave influence on the shallow bucket bearing response. These factors pose great challenges to the shallow bucket foundation design. This paper presents a set of centrifuge tests of a shallow bucket model subjected to monotonic and dynamic lateral loads to study the lateral bearing response of shallow bucket foundations in the field under combined loads induced by wind, waves, etc. In addition to the routine measurements (e.g., load-displacement), the soil pressures on the bucket and the distribution and evolution of the excess pore pressures in the surrounding soils are also obtained. The deformation pattern of the bucket (e.g., rotation center) is revealed through displacement measurements. Finally, the proposed easy-to-use analytical equations using the limit equilibrium to assess the bearing capacity of bucket foundations, taking into account the influence of the soil strength degradation caused by hydrodynamic wave loadings, are found to yield good results upon comparison with the centrifuge data, providing useful guidelines for the design of shallow bucket foundations.  相似文献   

A new combination of conditional environmental distributions     

《Applied Ocean Research》2018

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Frequent locations of oceanic fronts as an indicator of pelagic diversity: Application to marine protected areas and renewables     

《Marine Policy》2014

Frequent locations of thermal fronts in UK shelf seas were identified using an archive of 30,000 satellite images acquired between 1999 and 2008, and applied as a proxy for pelagic diversity in the designation of Marine Protected Areas (MPAs). Networks of MPAs are required for conservation of critical marine habitats within Europe, and there are similar initiatives worldwide. Many pelagic biodiversity hotspots are related to fronts, for example cetaceans and basking sharks around the Isle of Man, Hebrides and Cornwall, and hence remote sensing can address this policy need in regions with insufficient species distribution data. This is the first study of UK Continental Shelf front locations to use a 10-year archive of full-resolution (1.1 km) AVHRR data, revealing new aspects of their spatial and seasonal variability. Frontal locations determined at sea or predicted by ocean models agreed closely with the new frequent front maps, which also identified many additional frontal zones. These front maps were among the most widely used datasets in the recommendation of UK MPAs, and would be applicable to other geographic regions and to other policy drivers such as facilitating the deployment of offshore renewable energy devices with minimal environmental impact.  相似文献   

Subsurface eddies in the southern South China Sea detected from in-situ observation in October 2011     

《Deep Sea Research Part I: Oceanographic Research Papers》2014

Two anticyclonic subsurface eddies (SSEs) are detected from the in-situ hydrography data of the southern South China Sea (SCS) during 15–25 October 2011. Both SSEs have the lens-shaped water bodies below the thermocline. Their maximum swirl speed appears at the depth of lens׳ core, which is also characterized by a dump in the T–S diagram. These eddies do not have an enclosed saline-water or warm-water body in its lens׳ core, which is different from those SSEs reported in other seas. These SSEs should be locally generated by the horizontal shear of the Southeast Vietnam Offshore Current. In the SSE generation site of the southern SCS, there is an upper-layer anticyclonic eddy (AE2) that is right above the SSE (SE2). After leaving its generation site, the eddy loses its energy source and starts to weaken. In this case, the eddy will decay quickly in the upper layer due to the restraint of the thermocline, and finally evolves into a pure subsurface eddy (i.e. SE4).  相似文献   

Recent contributions of geotechnical centrifuge modelling to the understanding of jack-up spudcan behaviour     

Christophe Gaudin  Britta Bienen 《Ocean Engineering》2011,38(7):900-48

The paper presents an overview of the recent contributions of centrifuge modelling to the understanding of soil-structure interaction and the development of design and predictive methods in the field of mobile jack-up drilling rig foundations. Both advantages and limitations of the centrifuge methods are detailed and key examples are presented. The benefits provided by centrifuge modelling to the development of analysis methods that are now being used within the jack-up industry are highlighted. To conclude, industry trends and research opportunities are discussed, as is the possible role of the geotechnical centrifuge in finding solutions to these new needs.  相似文献   

On the potential for automated realtime detection of nonlinear internal waves from seafloor pressure measurements     

Uwe Stöber  James N. Moum 《Applied Ocean Research》2011,33(4):275-285

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Developing a robust SHM method for offshore jacket platform using model updating and fuzzy logic system   总被引：1，自引：0，他引：1  

A. Mojtahedi  M.A. Lotfollahi Yaghin  Y. Hassanzadeh  M.M. Ettefagh  M.H. Aminfar  A.B. Aghdam 《Applied Ocean Research》2011,33(4):398-411

Structural monitoring is essential for ensuring the structural safety performance during the service life. The process is of paramount importance in case of the offshore jacket-type platforms due to the underwater structural parts subjected to the marine environmental conditions. This work is an experimental investigation on a laboratory model of a jacket platform with the objective of establishing a baseline finite element (FE) model for long-term structural health monitoring for this type of structures. A robust damage diagnosis system is also developed which is less sensitive to both the measurements and the modeling uncertainties. Experimental vibration tests are conducted on a physical platform model to obtain dynamic characteristics and then, the initial FE-model of the intact structure is developed to determine them numerically. Some differences between numerically and experimentally identified characteristics emerge due to various uncertainties in the FE-model and measured vibration data. To minimize these differences, initial FE-model is updated according to the experimental results. The updated FE-model is employed to predict the changes in the dynamic characteristics under variety of damage scenarios which are imposed by reducing the stiffness at the components of the model. Fuzzy logic system (FLS) and probabilistic analysis is developed for linguistic classification of damage and global damage diagnosis. Incorporation of the FLS fault isolation technique into FE-model updating method are proposed and evaluated for two different FLS methods to develop a vigorous damage diagnosis method. The efficiency of the technique is validated by different damage scenarios foreseen on the physical model. This technique is shown to be effective for diagnosing the presence of degradation and quantify it.  相似文献   

Framing industrialization of the offshore wind value chain – A discourse approach to an event     

《Geoforum》2018

The paper explores value chain governance through a discourse approach to an event which included an exhibition and a conference. This approach appears promising for investigating industries in their formative phase and is particularly relevant for new renewable energy sectors. By studying the European offshore wind value chain, the paper investigates the coupling between wind industries and offshore industries as an encounter of various conventions. The key speakers at the conference, particularly those from the utility companies, introduced new principles for organizing the value chains they are leading, in order to reduce costs, and turn the immature sector into a mature one. Their storyline of industrialization by standardization breaks, however, with the storyline demonstrated by the firms in offshore oil and gas, and maritime industries at the exhibition. The latter offshore suppliers find evidence of quality in their business history and their trust-based relations to their clients. Theoretically the paper contributes to the global value chain governance debate by offering another perspective on power. The discourse approach helps us explain how influential actors could enforce one convention over another. The paper contributes methodically by suggesting a discourse approach to events. Events appear as a significant arena for negotiating industry formation and convenient for researcher’s data gathering for text analysis.  相似文献   

Comparing effects of land reclamation techniques on water pollution and fishery loss for a large-scale offshore airport island in Jinzhou Bay,Bohai Sea,China     

《Marine pollution bulletin》2013,72(1-2):29-40

Plans are being made to construct Dalian Offshore Airport in Jinzhou Bay with a reclamation area of 21 km². The large-scale reclamation can be expected to have negative effects on the marine environment, and these effects vary depending on the reclamation techniques used. Water quality mathematical models were developed and biology resource investigations were conducted to compare effects of an underwater explosion sediment removal and rock dumping technique and a silt dredging and rock dumping technique on water pollution and fishery loss. The findings show that creation of the artificial island with the underwater explosion sediment removal technique would greatly impact the marine environment. However, the impact for the silt dredging technique would be less. The conclusions from this study provide an important foundation for the planning of Dalian Offshore Airport and can be used as a reference for similar coastal reclamation and marine environment protection.  相似文献   

A numerical model for the transient analysis of offshore foundations under cyclic loading     

《Computers and Geotechnics》2014

A comprehensive numerical model for the analysis of offshore foundations under a general transient loading is presented here. The theoretical basis of the model lies on the Swansea formulation of Biot’s equations of dynamic poroelasticity combined with a constitutive model that reproduces key aspects of cyclic soil behaviour in the frame of the theory of generalised plasticity. On the practical side, the adoption of appropriate finite element formulations may prevent the appearance of spurious numerical instabilities of the pore pressure field. In this respect, the use of a coupled enhanced-strain element is here proposed. On the other hand, the practicality of the presented model depends ultimately on its computational efficiency. Some practical recommendations concerning the solution strategies, the matrix storage/handling procedures and the parallel multi-processor computation are here provided. Finally, the performance of the model with a benchmark study case and its practical application to analyse the soil–structure interaction of an offshore monopile under a realistic transient storm loading are discussed.  相似文献