Journal articles: 'Offshore foundations'

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Vølund, Per. "Concrete is the Future for Offshore Foundations." Wind Engineering 29, no. 6 (December 2005): 531–63. http://dx.doi.org/10.1260/030952405776234571.

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This paper compares the costs of using concrete foundations against steel monopile foundations for offshore wind turbines, and argues that concrete foundations will be cheaper. Most offshore windfarms have steel monopile foundations, but in Denmark concrete gravity foundations have been used with success. Two projects have tendered for steel monopiles and for concrete foundations and have implemented the concrete foundations that proved cheaper. No project has tendered for both foundation concepts and chosen steel monopiles. Nysted Offshore Windfarm with concrete foundations has the cheapest foundations of any offshore windfarm so far. A conceptual foundation study carried out for the London Array West Offshore Windfarm indicates that the same method and very low-cost foundations as for Nysted can be used. Optimised design of light-weight concrete constructions is the key to low-cost installation. Cheap manufacture can be carried out near the site or at even lower cost in Eastern Europa from where it can be shipped at little extra cost. The main construction of steel monopile foundations will become twice as costly as of concrete gravity foundations, and though installation is more costly for the gravity foundations it seems most likely that tendering between steel monopile and concrete gravity for London Array West will prove concrete considerably cheaper. It is argued that these considerations are to a wide extent generally valid, and also for very large turbines in deeper water. Concrete foundations will in 2006 be installed at Lillegrunden Offshore Windfarm in Sweden, and at Belgian Thornton Bank in 2006–7. So indications are strong that concrete is the future for offshore foundations.

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Esteban, M., José-Santos López-Gutiérrez, and Vicente Negro. "Gravity-Based Foundations in the Offshore Wind Sector." Journal of Marine Science and Engineering 7, no. 3 (March 12, 2019): 64. http://dx.doi.org/10.3390/jmse7030064.

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In recent years, the offshore wind industry has seen an important boost that is expected to continue in the coming years. In order for the offshore wind industry to achieve adequate development, it is essential to solve some existing uncertainties, some of which relate to foundations. These foundations are important for this type of project. As foundations represent approximately 35% of the total cost of an offshore wind project, it is essential that they receive special attention. There are different types of foundations that are used in the offshore wind industry. The most common types are steel monopiles, gravity-based structures (GBS), tripods, and jackets. However, there are some other types, such as suction caissons, tripiles, etc. For high water depths, the alternative to the previously mentioned foundations is the use of floating supports. Some offshore wind installations currently in operation have GBS-type foundations (also known as GBF: Gravity-based foundation). Although this typology has not been widely used until now, there is research that has highlighted its advantages over other types of foundation for both small and large water depth sites. There are no doubts over the importance of GBS. In fact, the offshore wind industry is trying to introduce improvements so as to turn GBF into a competitive foundation alternative, suitable for the widest ranges of water depth. The present article deals with GBS foundations. The article begins with the current state of the field, including not only the concepts of GBS constructed so far, but also other concepts that are in a less mature state of development. Furthermore, we also present a classification of this type of structure based on the GBS of offshore wind facilities that are currently in operation, as well as some reflections on future GBS alternatives.

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Schneider, James A., and Marc Senders. "Foundation Design: A Comparison of Oil and Gas Platforms with Offshore Wind Turbines." Marine Technology Society Journal 44, no. 1 (January 1, 2010): 32–51. http://dx.doi.org/10.4031/mtsj.44.1.5.

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AbstractThe offshore oil and gas (O&G) industry has over 70 years of experience developing innovative structures and foundation concepts for engineering in the marine environment. The evolution of these structures has strongly been influenced by water depth as well as soil conditions in the area of initial developments. As the offshore wind industry expands from the glacial soil deposits of the North and Baltic Seas, experience from the O&G industry can be used to aid a smooth transition to new areas. This paper presents an introduction to issues that influence how design and construction experience from the O&G industry can be used to aid foundation design for offshore wind energy converters. A history of the evolution of foundation and substructure concepts in the Gulf of Mexico and North Sea is presented, followed by a discussion of soil behavior and the influence of regional geology on these developments. Mechanisms that influence the resistance of shallow and deep foundations for fixed and floating offshore structures are outlined so that areas of empiricism within offshore design codes can be identified and properly modified for application to offshore wind turbine foundations. It is concluded that there are distinct differences between offshore O&G and offshore wind turbine foundations, and application of continued research into foundation behavior is necessary for rational, reliable, and cost-effective design.

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Barari, Amin, Britta Bienen, Domenico Lombardi, and Shinji Sassa. "Offshore Wind Turbine Foundations." Soils and Foundations 61, no. 2 (April 2021): 621–22. http://dx.doi.org/10.1016/j.sandf.2020.12.004.

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Ding, Hongyan, Yanjian Peng, Puyang Zhang, Hanbo Zhai, and Nan Jia. "Model Tests on the Penetration Resistance of Bucket Foundations for Offshore Wind Turbines in Sand." Journal of Marine Science and Engineering 8, no. 5 (May 22, 2020): 368. http://dx.doi.org/10.3390/jmse8050368.

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Driven by the rapid development of offshore wind farms, bucket foundations have come to constitute a very promising form of foundation for offshore wind turbines, mainly owing to their efficient construction. However, the penetration resistance of the suction penetration of a bucket foundation, when calculated inaccurately, may lead to installation failure of the foundation. In this study, model tests were performed on the suction penetration of a mono-bucket mono-compartment foundation and a mono-bucket multi-compartment foundation in saturated fine marine sand, aiming to compare their penetration resistances and critical suctions, and the development of a soil plug in the two models was analyzed. The results will provide a design reference for the penetration construction of bucket foundations for offshore wind turbines.

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Iwicki, Piotr, and Jarosław Przewłócki. "Short Review and 3-D FEM Analysis of Basic Types of Foundation for Offshore Wind Turbines." Polish Maritime Research 27, no. 3 (September 1, 2020): 31–39. http://dx.doi.org/10.2478/pomr-2020-0044.

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AbstractSome problems of the foundations of offshore wind turbines are considered in this paper. A short review is presented on the two basic types of foundations, i.e. monopiles and gravity foundations, including their basic features and applications as well as general design considerations. Also, some issues regarding analysis are discussed, including geotechnical problems and modelling techniques. A numerical model of offshores turbine and some preliminary computations are presented. Finite element analysis was carried out for wind turbines supported on both gravity and monopile foundations. The wind turbine tower, blades (simplified model), gravity foundation and part of the surrounding soil are included in the model. The turbine was loaded by wind and loads induced by waves, inertia and gravity. Both non-linear static and dynamic analysis of the wind turbine was performed. The displacements and stresses under the tower foundations were calculated and a comparison analysis carried out.

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Moller, Anders. "Efficient Offshore Wind Turbine Foundations." Wind Engineering 29, no. 5 (September 2005): 463–69. http://dx.doi.org/10.1260/030952405775992580.

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In the oil and gas industry, the foundations of offshore platforms have, for decades, used the grouted technique. This technology has now been transferred into the offshore wind turbine industry. This paper gives details of the use of the technology in some of the first offshore windfarms in Europe and considers future design possibilities.

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Lavanya, C., and Nandyala Darga Kumar. "Foundation Types for Land and Offshore Sustainable Wind Energy Turbine Towers." E3S Web of Conferences 184 (2020): 01094. http://dx.doi.org/10.1051/e3sconf/202018401094.

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Wind energy is the renewable sources of energy and it is used to generate electricity. The wind farms can be constructed on land and offshore where higher wind speeds are prevailing. Most offshore wind farms employ fixed-foundation wind turbines in relatively shallow water. In deep waters floating wind turbines have gained popularity and are recent development. This paper discusses the various types of foundations which are in practice for use in wind turbine towers installed on land and offshore. The applicability of foundations based on depth of seabed and distance of wind farm from the shore are discussed. Also, discussed the improvement methods of weak or soft soils for the foundations of wind turbine towers.

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Byrne, B. W., and G. T. Houlsby. "Foundations for offshore wind turbines." Philosophical Transactions of the Royal Society of London. Series A: Mathematical, Physical and Engineering Sciences 361, no. 1813 (November 4, 2003): 2909–30. http://dx.doi.org/10.1098/rsta.2003.1286.

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Clauss, G. F., and R. Schmitz. "Flat foundations for offshore platforms." International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts 27, no. 2 (April 1990): A110. http://dx.doi.org/10.1016/0148-9062(90)95236-t.

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11

Barari, Amin, and Lars Bo Ibsen. "VERTICAL CAPACITY OF BUCKET FOUNDATIONS IN UNDRAINED SOIL." JOURNAL OF CIVIL ENGINEERING AND MANAGEMENT 20, no. 3 (March 10, 2014): 360–71. http://dx.doi.org/10.3846/13923730.2013.801915.

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Offshore wind turbine structures are traditionally founded on gravity concrete foundations or mono-piles. Bucket foundations were developed for the offshore oil and gas industry and are now being used in wind turbine construction. The loading in this application is characterized by a vertical load due to the slender construction combined with horizontal forces inducing a large overturning moment. Field tests on bucket foundations were performed to gain insight into the vertical load response of bucket foundations in clay soils. The field tests were accompanied by finite element numerical simulations in order to provide a better understanding of the parameters influencing bucket foundation behaviour.

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Pan, Xiaodong, Ben He, Zonghao Yuan, Shiwu Xu, Danting Xu, Zhenqiang Jiang, Li Shi, and Honglei Sun. "Effect of Reinforced Bucket on Bearing Capacity and Natural Frequency of Offshore Wind Turbines Using Pile–Bucket Foundation." Advances in Civil Engineering 2022 (April 9, 2022): 1–17. http://dx.doi.org/10.1155/2022/9569102.

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Large-diameter monopiles have been widely used for constructing offshore wind turbines. The bearing capacity of a monopile foundation is a significant research problem. In this study, a new type of foundation, known as the pile–bucket foundation, was investigated to improve the bearing capacity of monopiles. A finite element software was used for establishing several numerical models of monopile and pile–bucket foundations to analyze the reinforcement afforded by the bucket attached to the monopile foundation. Furthermore, considering that offshore wind turbines are prone to resonance under the excitation of wind and wave loads, the natural frequencies of the monopile and pile–bucket foundations were determined and compared using both analytical and numerical methods. The results show that compared to the monopile foundation, the pile–bucket foundation has a significantly higher bearing capacity, mainly for large bucket diameters. The natural frequencies of the pile–bucket foundations are slightly higher than those of the monopile foundations. The addition of the bucket can effectively improve the natural frequency without changing the diameter of the monopile and thus saving the foundation cost.

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13

Sánchez, Sergio, José-Santos López-Gutiérrez, Vicente Negro, and M. Dolores Esteban. "Foundations in Offshore Wind Farms: Evolution, Characteristics and Range of Use. Analysis of Main Dimensional Parameters in Monopile Foundations." Journal of Marine Science and Engineering 7, no. 12 (December 2, 2019): 441. http://dx.doi.org/10.3390/jmse7120441.

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Renewable energies are the future, and offshore wind is undoubtedly one of the renewable energy sources for the future. Foundations of offshore wind turbines are essential for its right development. There are several types: monopiles, gravity-based structures, jackets, tripods, floating support, etc., being the first ones that are most used up to now. This manuscript begins with a review of the offshore wind power installed around the world and the exposition of the different types of foundations in the industry. For that, a database has been created, and all the data are being processed to be exposed in clear graphic summarizing the current use of the different foundation types, considering mainly distance to the coast and water depth. Later, the paper includes an analysis of the evolution and parameters of the design of monopiles, including wind turbine and monopile characteristics. Some monomials are considered in this specific analysis and also the soil type. So, a general view of the current state of monopile foundations is achieved, based on a database with the offshore wind farms in operation.

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Bhattacharya, Subhamoy, Domenico Lombardi, Sadra Amani, Muhammad Aleem, Ganga Prakhya, Sondipon Adhikari, Abdullahi Aliyu, et al. "Physical Modelling of Offshore Wind Turbine Foundations for TRL (Technology Readiness Level) Studies." Journal of Marine Science and Engineering 9, no. 6 (May 29, 2021): 589. http://dx.doi.org/10.3390/jmse9060589.

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Offshore wind turbines are a complex, dynamically sensitive structure due to their irregular mass and stiffness distribution, and complexity of the loading conditions they need to withstand. There are other challenges in particular locations such as typhoons, hurricanes, earthquakes, sea-bed currents, and tsunami. Because offshore wind turbines have stringent Serviceability Limit State (SLS) requirements and need to be installed in variable and often complex ground conditions, their foundation design is challenging. Foundation design must be robust due to the enormous cost of retrofitting in a challenging environment should any problem occur during the design lifetime. Traditionally, engineers use conventional types of foundation systems, such as shallow gravity-based foundations (GBF), suction caissons, or slender piles or monopiles, based on prior experience with designing such foundations for the oil and gas industry. For offshore wind turbines, however, new types of foundations are being considered for which neither prior experience nor guidelines exist. One of the major challenges is to develop a method to de-risk the life cycle of offshore wind turbines in diverse metocean and geological conditions. The paper, therefore, has the following aims: (a) provide an overview of the complexities and the common SLS performance requirements for offshore wind turbine; (b) discuss the use of physical modelling for verification and validation of innovative design concepts, taking into account all possible angles to de-risk the project; and (c) provide examples of applications in scaled model tests.

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15

Been, K., J. I. Clark, and W. R. Livingstone. "Verification and calibration studies for the new CAN/CSA-S472 foundations of offshore structures." Canadian Geotechnical Journal 30, no. 3 (June 1, 1993): 515–25. http://dx.doi.org/10.1139/t93-044.

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In June 1992, the Canadian Standards Association (CSA) published a code for the design, construction, and installation of fixed offshore structures. This code is relatively advanced in its application of limit states design to offshore structures. The part dealing with foundations is written as a performance standard. It does not specify resistance factors (or safety factors) to achieve the target reliability of the structure. Although limit states design is common practice among geotechnical engineers, the application of resistance factors is a problem. This paper describes some of the studies and conclusions reached by the Technical Committee in the development of the CSA foundations standard. As a first step, resistance factors were developed by calibration to conventional total factors of safety for the failure mechanisms considered. This approach has severe limitations. In particular, the applicability of safety factors developed for onshore practice or other offshore areas to the ice-dominated environment of Canadian offshore regions is questionable. In addition, many offshore structure designs include consideration of dynamic loading and scour or erosion problems that cannot be satisfactorily dealt with using factors of safety. An example of the problem of applying separate load and resistance factors for a bearing-capacity problem is given to show that load and resistance are not independent of each other. Because of the problems with development of resistance factors, the CSA foundations standard dictates that offshore structure designs include a risk analysis of the foundation system. A simple form of such an analysis for a caisson-retained sand structure is included in the paper. Key words : offshore structures, foundations, standard, safety, limit states design.

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Randolph, Mark. "Foundation and anchoring systems in soft sediments." Geotecnia, no. 94 (February 20, 2002): 05–35. http://dx.doi.org/10.14195/2184-8394_94_1.

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Offshore foundations and anchoring systems are being used increasingly in deep water conditions, where the seabed sediments are predominantly soft lightly overconsolidated sediments. The challenges of minimising the high costs of offshore installation without compromising reliability has led to major innovations in foundation types and installation methods, with consequential focus on new and improved analytical models. Examples of these include skirted foundations, where suction, or under pressure, is used to penetrate skirts to the required depth, and novel anchoring systems ranging from high capacity drag anchors to suction caissons. This lecture presents analysis and design methods for a range of foundation and anchoring systems in soft seabed sediments, including skirted foundations, suction emplaced caissons and drag anchors. Simplified analytical models of behaviour are described, the results from which are compared with those from numerical and physical modelling.

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Tayner, P. "Laying the foundations of offshore wind." Engineering & Technology 7, no. 10 (November 1, 2012): 83–84. http://dx.doi.org/10.1049/et.2012.1015.

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JGG. "Opinion: NEW FOUNDATIONS FOR OFFSHORE CENTRES." Trusts & Trustees 11, no. 10 (October 1, 2005): 4–5. http://dx.doi.org/10.1093/tandt/11.10.4.

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Byuna, Yong-Hoon, Kiwon Parkb, and Jong-Sub Lee. "Scour-monitoring techniques for offshore foundations." Smart Structures and Systems 16, no. 4 (October 25, 2015): 667–81. http://dx.doi.org/10.12989/sss.2015.16.4.667.

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Lee, C. Y., H. G. Poulos, and T. S. Hull. "Effect of seafloor instability on offshore pile foundations." Canadian Geotechnical Journal 28, no. 5 (October 1, 1991): 729–37. http://dx.doi.org/10.1139/t91-087.

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This paper employs a modified nonlinear boundary element approach to analyze the response of offshore piles subjected to external soil movements arising from submarine slides. Theoretical solutions for a realistic hypothetical offshore pile computed by the approach are presented and discussed. The analysis is then used to analyze the behaviour of two full-scale offshore piles in submarine slide areas, and reasonable agreement is found between observed and theoretical behaviour. Key words: seafloor instability, submarine slides, offshore piles, theoretical solutions, field tests.

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Zhu, Bin, Kai Wen, Tao Li, Lujun Wang, and Deqiong Kong. "Experimental study on lateral pile–soil interaction of offshore tetrapod piled jacket foundations in sand." Canadian Geotechnical Journal 56, no. 11 (November 2019): 1680–89. http://dx.doi.org/10.1139/cgj-2018-0292.

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Recently, tetrapod piled jacket (TPJ) foundations have shown considerable promise in offshore developments, due to the increases in power capacity and water depth for offshore wind turbines. This paper presents a set of centrifuge tests to look into the lateral loading behaviour of TPJ foundations in sand, with the overall load–displacement responses of the foundation as well as the soil resistance and internal forces on or within individual piles being examined carefully. Test results show that the back-row piles are more likely to be pulled out when the TPJ foundation is loaded laterally along the diagonal direction compared to when loaded along the orthogonal direction. The lateral soil resistance per unit length on the back-row pile(s) is approximately 60% of that on the front-row one(s) in the orthogonal loading case, and only about 40% in the diagonal loading case. Moreover, although the TPJ foundation is in its form a special case of pile groups, it is highlighted in the present study that the former case exhibits distinct loading behaviour from the latter case due to the typically large overturning moment encountered by the foundations for offshore wind turbines. Finally, the p-multipliers of the piles are demonstrated to be dependent on pile deflections, but independent on soil depths, and as a result, a modified pm model is proposed to provide guidance for the design of TPJ foundations in sand.

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Wang, Bin, Tianqing Qin, Changfeng Yuan, Liang Li, Minghui Yuan, and Ying Li. "Analysis of Bearing Performance of Monopile and Single Suction Bucket Foundation for Offshore Wind Power under Horizontal Load." Geofluids 2022 (June 8, 2022): 1–15. http://dx.doi.org/10.1155/2022/4163240.

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In conjunction with the geological conditions of the East China Sea, the bearing performance of monopile and single-suction bucket foundations is compared and analyzed in shallow and deep-sea conditions under static horizontal loads. Furthermore, the statistical data of wind and wave from 2010 to 2020 in the East China Sea were tabulated into amplitude curves applied to the two foundations in the form of dynamic loads, and the bearing performances of the two foundations under dynamic loads were analyzed. The results show that the typical suction bucket foundation for a wind turbine currently designed in the shallow sea is destabilized under static horizontal loads, while the pile foundation is more stable; both foundations are stable in the deep-sea area. However, the suction bucket foundation displacement is less than the pile foundation. Under dynamic loading, the maximum displacement of monopile in the shallow sea was 127 mm. The maximum displacement of the suction bucket foundation was 434 mm, and the foundation was unstable. Both foundations are stable in deep-sea conditions, and the maximum displacement of the pile foundation is 1.4 times the maximum displacement of the suction bucket. Considering the difficulty construction in the deep sea, it is recommended to use suction bucket foundations.

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Mei, Bi Xiang. "Study Finite Element Analysis of Monopile Foundation Based on Mechanical Mechanics and Properties of Steel Structure for Offshore Wind Turbines." Advanced Materials Research 743 (August 2013): 114–17. http://dx.doi.org/10.4028/www.scientific.net/amr.743.114.

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Statistical data shows that monopile foundation accounts for more than 65% of all foundations for offshore wind turbines,so it is of great engineering value to perform the research on the design and analysis of the monopile foundation. By its application environments and structure features,based on a design example of monopile foundation for a offshore wind farm,the paper performs the following sequence of works including the establishment of finite element model for monopile foundation, the calculation of foundation bearing capacity and deformation, modal analysis and fatigue analysis, etc.The paper gives the related design results, which is used for reference for designers.

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Shang, J. Q., E. Mohamedelhassan, and M. Ismail. "Electrochemical cementation of offshore calcareous soil." Canadian Geotechnical Journal 41, no. 5 (September 1, 2004): 877–93. http://dx.doi.org/10.1139/t04-030.

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The electrochemical stabilization processes are studied in a calcareous soil recovered from the Western Australia coast and on the interface of calcareous soil and steel foundation. A series of experiments are performed to study the effects of two chemical agents used in electrochemical stabilization tests. The strengthening effects of electro kinetics and electrochemical treatments on the calcareous soil are investigated first. Significant increases in the undrained shear strength and effective cohesion are obtained after all tests, and the most significant improvement is found after the electrochemical treatment using a 15% CaCl2 solution as the stabilization agent. Subsequently, an electrochemical test is carried out on the calcareous soil with an embedded steel plate to simulate a part of a caisson foundation, using CaCl2 as the stabilization agent. In this test, the practical considerations for later large-scale tests and ultimately for field implementation are taken into account in the design, including factors such as the attachment of electrodes to the foundation, injection of the stabilization agent via perforated pipe electrodes, and distributions of voltage and electrical current in the soil. The result of this test reveals a 700% increase in the steel plate axial load capacity after 7 days of treatment with an applied voltage of 4 V. The main features of the approach are that it generates virtually no disturbance to the soil and the treatment is targeted at the soilstructure interface. With further development, the electrochemical treatment may be applied in offshore engineering for stabilization of foundations installed in weak calcareous soils.Key words: calcareous soil, offshore foundations, soil improvement, chemical stabilization, electrokinetics.

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Stahlmann, Arne, and Torsten Schlurmann. "INVESTIGATIONS ON SCOUR DEVELOPMENT AT TRIPOD FOUNDATIONS FOR OFFSHORE WIND TURBINES: MODELING AND APPLICATION." Coastal Engineering Proceedings 1, no. 33 (October 25, 2012): 90. http://dx.doi.org/10.9753/icce.v33.sediment.90.

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Regarding offshore constructions, there is still a lack in knowledge of scour progression for complex structures like foundations for offshore wind energy converters at present, which is however necessary for its dimensioning. As an example of such complex structure types, tripod foundations are constructed in German offshore wind farms at present. In order to describe physical processes and influencing factors on scour progression from a scientific point of view, comprehensive investigations on the scouring phenomena for tripod foundations have been carried out and will be partly presented here. The overall investigation method consists of a combination of 1:40 small and 1:12 large scale physical model tests in wave flumes, numerical simulations using CFD methods and in-situ measured scour data. For the numerical modeling part, a sediment transport model formulation has been implemented into OpenFOAM software code. The results show a general variability of scour depending on the load boundary conditions and structural parameters. Scours occur both at the foundation piles and directly under the structure, which in this form could not be predicted using standard approaches, but which has to be taken into account when regarding the soil mechanical stability and the final dimensioning of the foundations.

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Yang, Ray-Yeng, Hsin-Hung Chen, Hwung-Hweng Hwung, Wen-Pin Jiang, and Nian-Tzu Wu. "EXPERIMENTAL STUDY ON THE LOADING AND SCOUR OF THE JACKET TYPE OFFSHORE WIND TURBINE FOUNDATION." Coastal Engineering Proceedings 1, no. 32 (January 21, 2011): 25. http://dx.doi.org/10.9753/icce.v32.structures.25.

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A 1:36 scale model tests were carried out in the Medium Wave Flume (MWF) and Near-shore Wave Basin (NSWB) at the Tainan Hydraulics Laboratory (THL) with the jacket type offshore wind turbine foundation located in the test area. The loading of typhoon wave with current on the jacket type offshore wind turbine foundation was investigated in the MWF with fixed bed experiment. Meanwhile, the scour around the jacket type offshore wind turbine foundation exposed to wave and current was conducted in the NSWB with the moveable bed experiment. Two locations (water depth 12m and 16m) of the foundations are separately simulated in this study. Based on the analysis from the former NSWB experimental results, the suitable scour protection of a four-layer work around the foundation is also proposed to the impact of scour. Finally, a four-layer scour protection is tested and found to be effective in preventing scour around jacket type foundation of offshore wind turbines at water depth 12m and 16m.

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Byrne, Byron, Guy Houlsby, Chris Martin, and Peter Fish. "Suction Caisson Foundations for Offshore Wind Turbines." Wind Engineering 26, no. 3 (May 2002): 145–55. http://dx.doi.org/10.1260/030952402762056063.

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This paper outlines a £ 1.5m, three year, research project that commenced during the middle of 2002 to determine a design framework for shallow foundations for offshore wind turbines. The shallow foundations in focus are suction-installed skirted foundations otherwise known as suction caissons (Houlsby and Byrne, 2000). There are eight distinct themes to the research covering all aspects of the geotechnical performance of these foundations. The funding for the project has been obtained from the Department of Trade and Industry (£ 917k), Industrial Partners (£ 373k) and the Engineering and Physical Sciences Research Council (£ 221k). The results will feed into the design process for offshore wind turbines almost immediately.

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Fazeres-Ferradosa, Tiago, João Chambel, Francisco Taveira-Pinto, Paulo Rosa-Santos, Francisco V. C. Taveira-Pinto, Gianmaria Giannini, and Piet Haerens. "Scour Protections for Offshore Foundations of Marine Energy Harvesting Technologies: A Review." Journal of Marine Science and Engineering 9, no. 3 (March 8, 2021): 297. http://dx.doi.org/10.3390/jmse9030297.

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The offshore wind is the sector of marine renewable energy with the highest commercial development at present. The margin to optimise offshore wind foundations is considerable, thus attracting both the scientific and the industrial community. Due to the complexity of the marine environment, the foundation of an offshore wind turbine represents a considerable portion of the overall investment. An important part of the foundation’s costs relates to the scour protections, which prevent scour effects that can lead the structure to reach the ultimate and service limit states. Presently, the advances in scour protections design and its optimisation for marine environments face many challenges, and the latest findings are often bounded by stakeholder’s strict confidential policies. Therefore, this paper provides a broad overview of the latest improvements acquired on this topic, which would otherwise be difficult to obtain by the scientific and general professional community. In addition, this paper summarises the key challenges and recent advances related to offshore wind turbine scour protections. Knowledge gaps, recent findings and prospective research goals are critically analysed, including the study of potential synergies with other marine renewable energy technologies, as wave and tidal energy. This research shows that scour protections are a field of study quite challenging and still with numerous questions to be answered. Thus, optimisation of scour protections in the marine environment represents a meaningful opportunity to further increase the competitiveness of marine renewable energies.

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Edwards, C. "Castles built on sand [offshore wind foundations]." Engineering & Technology 12, no. 7 (August 1, 2017): 46–49. http://dx.doi.org/10.1049/et.2017.0704.

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Nielsen, S. D., L. B. Ibsen, and B. N. Nielsen. "Advanced Laboratory Setup for Testing Offshore Foundations." Geotechnical Testing Journal 39, no. 4 (March 8, 2016): 20150135. http://dx.doi.org/10.1520/gtj20150135.

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Wu, Xiaoni, Yu Hu, Ye Li, Jian Yang, Lei Duan, Tongguang Wang, Thomas Adcock, et al. "Foundations of offshore wind turbines: A review." Renewable and Sustainable Energy Reviews 104 (April 2019): 379–93. http://dx.doi.org/10.1016/j.rser.2019.01.012.

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Gupta, Bipin K., and Dipanjan Basu. "Offshore wind turbine monopile foundations: Design perspectives." Ocean Engineering 213 (October 2020): 107514. http://dx.doi.org/10.1016/j.oceaneng.2020.107514.

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Zografou, Dimitra, Susan Gourvenec, and Conleth O’Loughlin. "Vertical cyclic loading response of shallow skirted foundation in soft normally consolidated clay." Canadian Geotechnical Journal 56, no. 4 (April 2019): 473–83. http://dx.doi.org/10.1139/cgj-2018-0179.

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Skirted foundations are a potential foundation solution for a range of offshore structures, including hydrocarbon and renewable energy platforms and subsea structures. Offshore foundations can be subject to cyclic loading from environmental, installation, and operational events affecting the geotechnical response. A series of centrifuge tests have been performed on a shallow skirted foundation on normally consolidated kaolin clay under a range of vertical cyclic load sequences to investigate the effect of tensile or compressive average stress, the magnitude of the applied stress, and the effect of cyclic loading of low magnitude followed by consolidation on the foundation response. Results are presented as vertical foundation displacements normalized by the foundation geometry and interpreted within the traditional shear-strain contour approach. The findings indicate that the average, rather than maximum, vertical stress defines the foundation vertical displacement response and failure mode, a threshold stress exists below which a steady state is maintained even at a high number of cycles, and geotechnical resistance increases as a result of low-level cyclic loading followed by consolidation.

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Andersson, Mathias H., and Marcus C. Öhman. "Fish and sessile assemblages associated with wind-turbine constructions in the Baltic Sea." Marine and Freshwater Research 61, no. 6 (2010): 642. http://dx.doi.org/10.1071/mf09117.

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Offshore wind farms are being built at a high rate around the world to meet the demand for renewable energy. We studied fish and sessile communities on and around offshore wind-turbine foundations in the southern Baltic Sea, 7 years after construction, using visual census techniques to determine how fish, sessile-invertebrate and algal communities are affected by the introduction of such structures. Fish assemblages were dominated by two-spotted gobies (Gobiusculus flavescens) that were found in large shoals in close association with the vertical surface. At the seabed, close to the foundation, the black goby (Gobius niger) was recorded in large numbers. The most obvious difference in fish densities was found between wind-power foundations extending through the entire water column and the surrounding open waters. Fouling assemblages on the vertical foundation surfaces and at the seabed just below differed from those at the seabed further away by having higher coverage of blue mussel (Mytilus edulis) and less algal growth. The results from the present study suggest that the introduction of offshore wind turbines in marine waters could have a positive effect on fish numbers and the presence of sessile invertebrates.

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Ni, Xuan, and Leiping Xue. "Experimental Investigation of Scour Prediction Methods for Offshore Tripod and Hexapod Foundations." Journal of Marine Science and Engineering 8, no. 11 (October 30, 2020): 856. http://dx.doi.org/10.3390/jmse8110856.

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Scour prediction is essential for the design of offshore foundations. Several methods have been proposed to predict the equilibrium scour depth for monopiles. By introducing an effective diameter, such methods could also be applied to predicting scour depth for pile groups. Yet, there are still difficulties in estimating the equilibrium scour depth of foundations in complex shapes, such as the tripod foundation. This study investigates the clear-water scour around the tripod and hexapod foundations through laboratory experiments, with uniform bed sediment and steady current. Here, the authors propose an approach to calculate the effective diameter for the tripod and hexapod models, which is similarly as for the pile groups. Three widely-used methods in predicting equilibrium scour depth have been evaluated, and the best method is recommended.

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Zhang, Pei, Shugeng Yang, Yan Li, Jiayang Gu, Zhiqiang Hu, Ruoyu Zhang, and Yougang Tang. "Dynamic Response of Articulated Offshore Wind Turbines under Different Water Depths." Energies 13, no. 11 (June 1, 2020): 2784. http://dx.doi.org/10.3390/en13112784.

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Focusing on the transitional depth offshore area from 50 m to 75 m, types of articulated foundations are proposed for supporting the NREL 5 MW offshore wind turbine. To investigate the dynamic behaviors under various water depths, three articulated foundations were adopted and numerical simulations were conducted in the time domain. An in-house code was chosen to simulate the dynamic response of the articulated offshore wind turbine. The aerodynamic load on rotating blades and the wind pressure load on tower are calculated based on the blade element momentum theory and the empirical formula, respectively. The hydrodynamic load is simulated by 3D potential flow theory. The motions of foundation, the aerodynamic performance of the wind turbine, and the loads on the articulated joint are documented and compared in different cases. According to the simulation, all three articulated offshore wind turbines show great dynamic performance and totally meet the requirement of power generation under the rated operational condition. Moreover, the comparison is based on time histories and spectra among these responses. The result shows that dynamic responses of the shallower one oscillate more severely compared to the other designs.

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Mana, Divya S. K., Susan Gourvenec, and Mark F. Randolph. "Experimental investigation of reverse end bearing of offshore shallow foundations." Canadian Geotechnical Journal 50, no. 10 (October 2013): 1022–33. http://dx.doi.org/10.1139/cgj-2012-0428.

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Shallow skirted foundations can mobilize uplift resistance from end bearing in the short to medium term. However, uncertainty exists over the magnitude of reverse end bearing resistance compared with resistance in compression, and how this might be affected by a gap between the external face of the foundation skirt and the adjacent soil. The study presented in this paper explores this problem through centrifuge model tests, investigating the effect of skirt embedment ratio on (i) the magnitude of reverse end bearing capacity compared with compression capacity, (ii) the uplift displacement associated with spontaneous loss of suction during uplift, and (iii) the existence of a vertical gap along the external skirt–soil interface. The results show that (i) peak uplift capacity equivalent to compression capacity can be mobilized for a fully sealed foundation with an intact skirt–soil interface, (ii) suction required for reverse end bearing can be maintained through considerable foundation displacement, even for a low skirt embedment ratio, and (iii) the presence of a vertical gap along the external skirt–soil interface causes abrupt loss of suction beneath the top plate after minimal foundation displacement, with subsequent uplift capacity being markedly reduced.

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Mrazek, Yann. "UAE private foundations—an overview." Trusts & Trustees 26, no. 6 (July 1, 2020): 595–99. http://dx.doi.org/10.1093/tandt/ttaa028.

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Abstract Most Middle Eastern entrepreneurial families are familiar with foreign offshore trusts and foundations and have been using these tools to ensure wealth preservation and inter-generational continuity for several generations. In that context, the United Arab Emirates (UAE) now counts three foundation regimes (in the Abu Dhabi Global Market, the Dubai International Financial Centre and the Ras Al Khaimah International Corporate Centre) and provides a local solution to wealth management and preservation, family succession planning, corporate structuring and asset protection. The purpose of this article is to present the context, mechanisms and interests in relation to UAE private foundations.

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Micic, S., J. Q. Shang, and K. Y. Lo. "Improvement of the load-carrying capacity of offshore skirted foundations by electrokinetics." Canadian Geotechnical Journal 40, no. 5 (October 1, 2003): 949–63. http://dx.doi.org/10.1139/t03-045.

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Originating from the problem facing offshore foundation engineering, the present study is focused on using electrokinetics to enhance the load-carrying capacity of skirted foundations embedded in soft marine deposits. An experimental study was carried out in a model tank having dimensions of 150 cm × 75 cm × 70 cm. The experiments were conducted on the Welland River sediment mixed with a high salinity solution that simulates the composition of seawater. A steel cylinder of 320 mm in diameter was embedded in the sediment to represent a skirted foundation. Electrodes were installed around the steel cylinder, and a voltage of 5.2 V was applied over 28 days with polarity reversal. The load-carrying capacity of the steel cylinder and the undrained shear strength of the adjacent soil were measured after the electrokinetic treatment. The effect of electrokinetics is evaluated by comparing a series of test results performed on the untreated and treated soil. The load-carrying capacity of the steel cylinder and the undrained shear strength of the adjacent soil increased up to three times after treatment. The study also shows that electrokinetics can regain and further enhance the load carrying capacity of the embedded skirted foundation model after failure. With further development, the technology has the potential to be applied in offshore engineering practice to increase the load-carrying capacity of skirted foundations installed in soft clayey sediments.Key words: electrokinetics, skirted foundations, soft marine clay, load-carrying capacity, soil improvement.

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Wang, Mingyuan, Miao Wang, Xinglei Cheng, Qun Lu, and Jiaqing Lu. "A New p–y Curve for Laterally Loaded Large-Diameter Monopiles in Soft Clays." Sustainability 14, no. 22 (November 15, 2022): 15102. http://dx.doi.org/10.3390/su142215102.

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In harsh offshore environmental conditions, the monopile foundations supporting offshore wind turbines must be designed for lateral loads such as winds, waves, and currents. The Beam on Nonlinear Winkler Foundation (BNWF) method has been widely used because of its clear concept and lower calculation cost. The selection of a reasonable p–y curve is critical to the calculation accuracy of this method. This paper clarified the defects of widely used API p–y curves for soft clays and then proposed a new p–y curve with better versatility and applicability. The suitability of the proposed p–y curve was validated by comparing it with the calculation results from the three-dimensional finite element method (3D FEM). Compared with the API p–y curve, the proposed p–y curve can better predict the lateral behavior of large-diameter piles in soft clays, such as the load–displacement curve of the pile head, lateral deflection profile, and bending moment profile. The research findings can provide guidance for the design of monopile foundations supporting offshore wind turbines in soft clays.

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Yun, Gijae, and M. Fraser Bransby. "The horizontal-moment capacity of embedded foundations in undrained soil." Canadian Geotechnical Journal 44, no. 4 (April 1, 2007): 409–24. http://dx.doi.org/10.1139/t06-126.

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The bearing capacity of embedded foundations subject to combined horizontal and moment loading in undrained soils is of interest particularly to the offshore geotechnical engineer. These loadings can be experienced by monopod foundations and offshore manifolds and often take the form of a horizontal load applied at a lever arm height above the foundation base. Previous design methods using the failure envelope approach have suggested that peak moment capacity of a foundation is mobilized with positive horizontal loads, but that peak horizontal load is mobilized with no additional moment loading. This paper reports numerical work specifically investigating the effects of the embedment ratio on the horizontal-moment foundation capacity under no vertical load in both uniform strength and "normally consolidated" undrained soil. It is shown that the embedment ratio significantly affects the eccentricity of the M–H failure envelope so that the shape varies when normalized by the pure moment (M0) and pure horizontal load (H0) capacity. The reasons for the eccentricity of the failure envelopes are understood by investigating soil deformation mechanisms calculated during FE analysis and by accompanying upper bound plasticity analysis. This mechanistic understanding is used to suggest load reference point translations that ease curve-fitting of the complex failure envelopes for use in design.Key words: bearing capacity, foundations, numerical modelling and analysis, plasticity.

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Passon, Patrik, and Kim Branner. "Load calculation methods for offshore wind turbine foundations." Ships and Offshore Structures 9, no. 4 (August 6, 2013): 433–49. http://dx.doi.org/10.1080/17445302.2013.820108.

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Wu, Tien H., Wilson H. Tang, Dwight A. Sangrey, and Gregory B. Baecher. "Reliability of Offshore Foundations—State of the Art." Journal of Geotechnical Engineering 115, no. 2 (February 1989): 157–78. http://dx.doi.org/10.1061/(asce)0733-9410(1989)115:2(157).

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Craig, William H., and Keng Chua. "Extraction Forces for Offshore Foundations under Undrained Loading." Journal of Geotechnical Engineering 116, no. 5 (May 1990): 868–84. http://dx.doi.org/10.1061/(asce)0733-9410(1990)116:5(868).

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Sun, Liqiang, Yumeng Qi, Xiaowei Feng, and Zhengqing Liu. "Tensile capacity of offshore bucket foundations in clay." Ocean Engineering 197 (February 2020): 106893. http://dx.doi.org/10.1016/j.oceaneng.2019.106893.

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Manzano-Agugliaro, Francisco, Miguel Sánchez-Calero, Alfredo Alcayde, Carlos San-Antonio-Gómez, Alberto-Jesús Perea-Moreno, and Esther Salmeron-Manzano. "Wind Turbines Offshore Foundations and Connections to Grid." Inventions 5, no. 1 (January 28, 2020): 8. http://dx.doi.org/10.3390/inventions5010008.

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Most offshore wind farms built thus far are based on waters below 30 m deep, either using big diameter steel monopiles or a gravity base. Now, offshore windfarms are starting to be installed in deeper waters and the use of these structures—used for oil and gas like jackets and tripods—is becoming more competitive. Setting aside these calls for direct or fixed foundations, and thinking of water depths beyond 50 m, there is a completely new line of investigation focused on the usage of floating structures; TLP (tension leg platform), Spar (large deep craft cylindrical floating caisson), and semisubmersible are the most studied. We analyze these in detail at the end of this document. Nevertheless, it is foreseen that we must still wait sometime before these solutions, based on floating structures, can become truth from a commercial point of view, due to the higher cost, rather than direct or fixed foundations. In addition, it is more likely that some technical modifications in the wind turbines will have to be implemented to improve their function. Regarding wind farm connections to grid, it can be found from traditional designs such as radial, star or ring. On the other hand, for wind generator modeling, classifications can be established, modeling the wind turbine and modeling the wind farm. Finally, for the wind generator control, the main strategies are: passive stall, active stall, and pitch control; and when it is based on wind generation zone: fixed speed and variable speed. Lastly, the trend is to use strategies based on synchronous machines, as the permanent magnet synchronous generator (PMSG) and the wound rotor synchronous generator (WRSG).

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Peng, Zhong. "WAVE SLAMMING IMPACT ON OFFSHORE WIND TURBINE FOUNDATIONS." Coastal Engineering Proceedings 1, no. 34 (October 30, 2014): 43. http://dx.doi.org/10.9753/icce.v34.waves.43.

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Kristiansen, Morten, Radoslav Darula, Benny Endelt, Anders Faarbæk Mikkelstrup, Jan Schjødt-Thomsen, Jens Henrik Andreasen, Farhang Farrokhi, et al. "Improving the fatigue life of large offshore foundations." Marine Structures 87 (January 2023): 103314. http://dx.doi.org/10.1016/j.marstruc.2022.103314.

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Davidson, Alasdair, and Jasmin Semlitsch. "‘Solid foundations’: the advantages of using Guernsey Foundations for building a family office." Trusts & Trustees 25, no. 6 (July 1, 2019): 668–72. http://dx.doi.org/10.1093/tandt/ttz052.

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Abstract Family office services are gaining ever-increasing popularity and traction across the global offshore financial centres. The key characteristics and distinctions of Guernsey’s foundation regime make it a particularly effective tool for wealthy individuals and their dedicated family offices to achieve an array of investment, succession planning, or philanthropic objectives. In this article, we explore how Guernsey foundations can cater for the desired levels of control, tailor the rights of beneficiaries, maintain confidentiality, and be used in new and innovative ways to enhance and complement wealth management structures.

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Wang, Guilan, Yi Gan, Conghuan Le, Ruiyang Yan, and Xueyang Hu. "Bearing Characteristics of Tripod Bucket Jacket Foundation for Offshore Wind Turbines in Sand under Monotonic Loads." Journal of Marine Science and Engineering 10, no. 2 (February 1, 2022): 199. http://dx.doi.org/10.3390/jmse10020199.

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Tripod bucket jacket foundation is an alternative foundation solution for deep-sea wind farms. This paper analyzes and compares the bearing characteristics of two tripod bucket jacket foundations with different height-diameter ratios, the tripod suction pile jacket foundation (TSPJF) and tripod bucket jacket foundation (TBJF), under different monotonic loads. The bearing modes of the two foundations under the vertical loads are different. The ultimate vertical load is mainly borne by the inside frictional resistance for the TSPJF, while it is mainly borne by the lid resistance for the TBJF. The foundations will take place translation and rotation under horizontal load. Under the positive x-axis loading, the vertical resistance of the TSPJF and TBJF is mainly composed of the soil resistance on the 1# bucket lid, the inside and outside frictional resistance. Under the negative x-axis loading condition, the vertical resistance is mainly composed of the inside and outside frictional resistance of buckets. The ultimate moment capacities of the TSPJF and TBJF in loading of the single bucket in compression is significantly larger than that in loading of the single bucket in tension. The failure mode of the TSPJF and TBJF in loading of the single bucket in tension is the pull-out failure of the bucket in tension.

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Journal articles on the topic 'Offshore foundations'

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