Centrifuge test of a clustered bucket foundation for offshore wind towers

The composite bucket foundation (CBF) for offshore wind turbines is the basis for a one-step integrated transportation and installation technique, which can be adapted to the construction and development needs of offshore wind farms due to its special structural form. To transport and install bucket foundations together with the upper portion of offshore wind turbines, a non-self-propelled integrated transportation and installation vessel was designed. In this paper, as the first stage of applying the proposed one-step integrated construction technique, the floating behavior during the transportation of CBF with a wind turbine tower for the Xiangshui wind farm in the Jiangsu province was monitored. The influences of speed, wave height, and wind on the floating behavior of the structure were studied. The results show that the roll and pitch angles remain close to level during the process of lifting and towing the wind turbine structure. In addition, the safety of the aircushion structure of the CBF was verified by analyzing the measurement results for the interaction force and the depth of the liquid within the bucket. The results of the three-DOF (degree of freedom) acceleration monitoring on the top of the test tower indicate that the wind turbine could meet the specified acceleration value limits during towing.

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Lifting Technique of Composite Bucket Foundation for Offshore Wind Turbines

Volume 9: Ocean Renewable Energy ◽

10.1115/omae2020-18404 ◽

2020 ◽

Author(s):

Hongyan Ding ◽

Zuntao Feng ◽

Puyang Zhang ◽

Conghuan Le

Keyword(s):

Finite Element ◽

Prestressed Concrete ◽

Large Scale ◽

Element Model ◽

Offshore Wind ◽

Force Transmission ◽

Element Analysis ◽

Bucket Foundation ◽

Transition Section ◽

Section Structure

Abstract The onshore pre-fabrication technology for composite bucket foundations takes “prefabrication-assembly-lifting” as the core concept. The practice of pre-fabrication of upper and lower structures is prefabricated respectively. In the research of hoisting engineering technology, combined with the structural form and construction requirements of composite bucket foundation, the assembly scheme of the upper prestressed concrete transition section and the lower steel bucket and the hoisting scheme of integral foundation with compartments were designed. The finite element model in the lifting process of composite bucket foundation was established by the large-scale general finite element analysis software ABAQUS. For the optimization analysis of the lifting point arrangement during hoisting process, the number, position and arrangement form of lifting points are simulated and analyzed. The results show that the maximum value of the principal stress of the concrete transition section structure appears in the assembly stage with the lower steel bucket, and the structure checking calculation should be carried out as the most unfavorable lifting condition in construction; the peak point of structural stress is at the junction of girder and secondary beams and inner ring beams of concrete roof, which belongs to the weak position of force transmission. In construction, it should be paid attention to as the key part of monitoring to ensure composite bucket foundation is under reasonable stress and the stability in the lifting process. The research results can provide guidance and reference for the future batch production and standardization production construction for composite bucket foundations.

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Review for "Studies on cyclic behavior of tripod suction bucket foundation system supporting offshore wind turbine using centrifuge model test"

10.1002/we.2586/v2/review2 ◽

2020 ◽

Author(s):

Xuefei Wang

Keyword(s):

Wind Turbine ◽

Model Test ◽

Offshore Wind ◽

Cyclic Behavior ◽

Offshore Wind Turbine ◽

Centrifuge Model Test ◽

Bucket Foundation ◽

Centrifuge Model

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Decision letter for "Studies on cyclic behavior of tripod suction bucket foundation system supporting offshore wind turbine using centrifuge model test"

10.1002/we.2586/v2/decision1 ◽

2020 ◽

Keyword(s):

Wind Turbine ◽

Model Test ◽

Offshore Wind ◽

Cyclic Behavior ◽

Offshore Wind Turbine ◽

Centrifuge Model Test ◽

Bucket Foundation ◽

Centrifuge Model

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Model tests for tilting control of suction bucket foundation for offshore wind turbine with path points

Korean Society of Hazard Mitigation ◽

10.9798/kosham.2021.21.3.125 ◽

2021 ◽

Vol 21 (3) ◽

pp. 125-132

Author(s):

You-Seok Kim ◽

Jong-Pil Lee

Keyword(s):

Control Method ◽

Wind Farms ◽

Offshore Wind ◽

Scale Model ◽

Positive Pressure ◽

Offshore Wind Turbine ◽

Offshore Wind Farms ◽

Bucket Foundation ◽

Model Foundation ◽

Ground Condition

In offshore wind farms, tilting control based on a single-basket suction bucket foundation is a significant problem. In a single-basket suction bucket foundation, the tilting control of the foundation is possible by arranging the cells inside and controlling the pressure of each cell. However, the pressure of each cell must be finely controlled. Studies on this topic have been conducted, but no specific tilting control method has been developed. This paper presents experimental model results for tilting control obtained during the installation of a suction bucket foundation consisting of three internal cells. Tilting control was performed by independently controlling the internal pressure of each cell. A 1:100 scale model was used, and the ground condition was sandy. Four cases of tilting control tests for the model foundation were used with multiple combinations of internal positive, negative, or both pressures of each cell. It was found that the tilting control was within 5° during the installation and operation stages. There was a tilting control limit for operation based on the model with only negative pressure; therefore, 5° tilting control was achieved by combining the positive pressure.

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Failure Envelopes of Composite Bucket Foundation for Offshore Wind Turbines under Combined Loading with considering Different Scour Depths

Shock and Vibration ◽

10.1155/2021/7922572 ◽

2021 ◽

Vol 2021 ◽

pp. 1-15

Author(s):

Yuanxu Jing ◽

Yuan Wang ◽

Jingqi Huang ◽

Wei Wang ◽

Lunbo Luo

Keyword(s):

Wind Turbines ◽

Bending Moment ◽

Offshore Wind ◽

Combined Loading ◽

Failure Envelope ◽

Bucket Foundation ◽

Offshore Wind Turbines ◽

Failure Envelopes ◽

The Stability ◽

The Right

The composite bucket foundation of offshore wind turbines is subjected to a variety of loads in the marine environment, such as horizontal load H, vertical load V , bending moment M, and torque T. In addition, due to the characteristics of its connection section, the water flow around the foundation will produce scour pits of various degrees, reducing the depth of the bucket foundation, which has a nonnegligible impact on the overall stability of the bucket foundation. In this paper, the failure envelope characteristics of different combinations of loads on bucket foundations, including V -H-T, V -M-T, conventional V -H-M, and noncoplanar V -H-M, are numerically investigated with considering different scour depths. The numerical results indicate that the V -H-T, V -M-T, conventional V -H-M, and noncongruent V -H-M failure envelopes gradually shrink inwards with increasing scour depth, and the stability of the composite bucket foundation decreases; the conventional V -H-M failure envelope shows an asymmetry of convexity to the right, and the noncongruent V -H-M failure envelope shows an asymmetry of outward convexity to the left and right. The corresponding mathematical expressions for the failure envelope are obtained through the normalized fitting process, which can be used to evaluate the stability of the bucket foundation based on the relative relationship between the failure envelope and the actual load conditions, which can provide practical guidance for engineering design.

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