Installation and lateral loading tests of suction caissons in silt

2011 ◽  
Vol 48 (7) ◽  
pp. 1070-1084 ◽  
Author(s):  
Bin Zhu ◽  
De-qiong Kong ◽  
Ren-peng Chen ◽  
Ling-gang Kong ◽  
Yun-min Chen
Keyword(s):  
Wind Turbines ◽  
Large Scale ◽  
Lateral Loading ◽  
Offshore Wind ◽  
Scale Model ◽  
Moment Capacity ◽  
Offshore Wind Turbines ◽  
Rotation Center ◽  
Cone Penetration Tests ◽  
Caisson Foundations

A number of potential offshore wind turbines in China will be constructed in sandy silt seabeds, and the mono-caisson foundation is an important choice for these offshore wind turbines. A program of large-scale model tests on suction installation and lateral loading of caisson foundations in saturated silt were carried out in a large soil tank at Zhejiang University. Test results of installation resistance during suction installation show that the seepage effect is limited in silt, and the suction required to penetrate the caisson can be well predicted based on the sleeve friction and cone resistance of cone penetration tests. The deformation mechanism and soil-structure interaction of a caisson subjected to lateral loads were investigated. The instantaneous rotation center of the model caisson at failure was at the depth of about four-fifths of the skirt length, almost directly below the lid center. Based on the assumption of a common position of the instantaneous rotation center and dominating resistance forces on the caisson, an analytical expression for the ultimate moment capacity was presented.

Experimental Study on Installation of Composite Bucket Foundations for Offshore Wind Turbines in Silty Sand

2016 ◽  
Vol 138 (6) ◽  
Author(s):  
Puyang Zhang ◽  
Zhi Zhang ◽  
Yonggang Liu ◽  
Hongyan Ding
Keyword(s):  
Wind Turbines ◽  
Large Scale ◽  
Silty Sand ◽  
Offshore Wind ◽  
Scale Model ◽  
Positive Pressure ◽  
Adjustment Process ◽  
Outer Diameter ◽  
Bucket Foundation ◽  
Offshore Wind Turbines

The composite bucket foundation (CBF) is a cost-competitive foundation for offshore wind turbines, which can be adapted to the loading characteristics and development needs of offshore wind farms due to its special structural form. There are seven sections divided inside the CBF by steel bulkheads, which are arranged in a honeycomb structure. The six peripheral sections with the skirt have the same proportions while the middle orthohexagonal one is a little larger. With the seven-section structure, the CBF has reasonable motion characteristics and towing reliability during the wet-tow construction process. Moreover, the pressure inside the compartments can control the levelness of the CBF during suction installation. Several large-scale model tests on suction installation of CBF have been performed in order to explore the feasibility of the tilt adjusting technique in saturated silty sand off the coast of Jiangsu in China. The composite bucket foundation in the tests has an outer diameter of 3.5 m and a clear wall height of 0.9 m. During the suction-assisted penetration process, the pressures in all the compartments were controlled to level the foundation in a timely operation. A convenient method is to improve the CBF inclination by controlling the inside differential pressure among the compartments. It can be commonly carried out by applying suction/positive pressure with intermittent pumping among the seven compartments. Another adjusting technique for a big tilt with deeper penetration is operated with decreasing the penetration depth achieved by suction-assisted lowering the relatively high compartments and positive pressures raising the relatively low compartments. Test results show that the reciprocating adjustment process can be repeated until the CBF is completely penetrated into a designed depth.

Development of a CFD-CSD Coupling Technique for Large Scale Offshore Wind Turbines

2020 ◽  
Author(s):  
Auraluck Pichitkul ◽  
Lakshmi N. Sankar
Keyword(s):  
Fluid Dynamics ◽  
Renewable Energy ◽  
Wind Turbines ◽  
Large Scale ◽  
Time History ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Renewable Energy Resources ◽  
Aerodynamic Loads ◽  
Offshore Wind Turbines

Abstract Wind engineering technology has been continuously investigated and developed over the past several decades in response to steadily growing demand for renewable energy resources, in order to meet the increased demand for power production, fixed and floating platforms with different mooring configurations have been fielded, accommodating large-scale offshore wind turbines in deep water areas. In this study, the aerodynamic loads on such systems are modeled using a computational structural dynamics solver called OpenFAST developed by National Renewable Energy Laboratory, coupled to an in-house computational fluid dynamics solver called GT-Hybrid. Coupling of the structural/aerodynamic motion time history with the CFD analysis is done using an open File I/O process. At this writing, only a one-way coupling has been attempted, feeding the blade motion and structural deformations from OpenFAST into the fluid dynamics analysis. The sectional aerodynamic loads for a large scale 5 MW offshore wind turbine are presented, and compared against the baseline OpenFAST simulations with classical blade element-momentum theory. Encouraging agreement has been observed.

Research on the influence of large scale offshore wind turbines integrated into Jiangsu power system

2021 ◽  
Author(s):  
C. Hui ◽  
P. Zhuyi ◽  
Z. Xingyu ◽  
X. Zhenjian ◽  
X. Sixuan ◽  
...  
Keyword(s):  
Power System ◽  
Wind Turbines ◽  
Large Scale ◽  
Offshore Wind ◽  
Offshore Wind Turbines

Geotechnical Stability of Gravity Base Foundations for Offshore Wind Turbines on Granular Soils

2012 ◽  
Author(s):  
Germán Sedlacek ◽  
Alina Miehe ◽  
Ana Libreros ◽  
Yousef Heider
Keyword(s):  
Wind Energy ◽  
Wind Turbines ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Good Alternative ◽  
Offshore Wind ◽  
Scale Model ◽  
Offshore Wind Turbines ◽  
Geotechnical Design ◽  
And Performance

Offshore wind energy farms have gained much attention during the last years in Germany and all over the world. In the construction of offshore wind turbines, piled foundations have been mostly used so far. However, gravity base foundations represent a good alternative as they minimize the typical high risks of the offshore works, such as weather-dependent installation, operational safety, construction sequence and performance. The whole wind energy turbine is assembled onshore and promptly transported to the planned location. In the design of the gravity foundation under cyclic loading conditions, it is essential to avoid inadmissibly large reductions of the subsoil bearing capacity due to the excess pore-water pressure (loss of stability) and tilting of the foundation caused by the accumulation of settlements (loss of serviceability). This paper provides a description of the soil-mechanical behaviour of gravity base foundations and gives an account of the current available rules and standards for dimensioning foundations of this type. In this regard, a procedure for the geotechnical design of a gravity base foundation is laid out, where this work points out that the existing standards for designing gravity base foundations need to be further developed. Moreover, a brief summary of the results at a full-scale model test, according to the present state of testing and knowledge, are given.

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