The Experts below are selected from a list of 7800 Experts worldwide ranked by ideXlab platform
Tian Tang - One of the best experts on this subject based on the ideXlab platform.
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numerical analysis of wave induced poro elastic seabed response around a hexagonal gravity based Offshore Foundation
Coastal Engineering, 2018Co-Authors: Muk Chen Ong, Tian TangAbstract:Abstract In order to prevent the future risk of soil and structural failures for the Offshore Foundations, it is essential to evaluate the seabed soil behaviors in the vicinity of the Foundation under dynamic wave loadings. The objective of this paper is to investigate the wave-induced soil response and liquefaction risk around a hexagonal gravity-based Offshore Foundation. Three-dimensional (3D) numerical analysis is performed by applying an integrated multiphysics model developed in the finite volume method (FVM) based OpenFOAM framework. The integrated model incorporates solvers of the nonlinear waves, the linear elastic structure and the anisotropic poro-elastic seabed soil. The free surface model and soil model are verified by grid convergence studies. The wave-induced soil response model is validated by reproducing a laboratory experiment and a good agreement is obtained. Distributions of wave-induced shear stress, pore pressure, vertical displacement and seepage flow structure in the seabed are investigated. It is found that the presence of the Foundation significantly amplifies the wave-induced shearing effect and vertical displacement in the underlying seabed soil. Seabed consolidation state in the presence of the structure is evaluated. Since the Foundation is embedded in the seabed at a depth, the vertices of the hexagonal Foundation cause the stress concentration in the nearby soil during the consolidation process. Therefore, the momentary liquefaction at the vertices is not as significant as that at the edges due to the high initial effective stress. A parametric study with different wave heights is conducted to examine the changes of soil response and momentary liquefaction depth around the hexagonal Foundation. Effects of isotropic and anisotropic soil permeability on the pore pressure distribution are investigated. It shows that the effect of anisotropic permeability should be considered for the medium sand that is modelled in the present study.
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investigation of nonlinear wave induced seabed response around mono pile Foundation
Coastal Engineering, 2017Co-Authors: Zaibin Lin, Dubravka Pokrajac, Yakun Guo, Dongsheng Jeng, Tian Tang, Nick Rey, Jinhai Zheng, Jisheng ZhangAbstract:Abstract Stability and safety of Offshore wind turbines with mono-pile Foundations, affected by nonlinear wave effect and dynamic seabed response, are the primary concerns in Offshore Foundation design. In order to address these problems, the effects of wave nonlinearity on dynamic seabed response in the vicinity of mono-pile Foundation is investigated using an integrated model, developed using OpenFOAM, which incorporates both wave model (waves2Foam) and Biot's poro-elastic model. The present model was validated against several laboratory experiments and promising agreements were obtained. Special attention was paid to the systematic analysis of pore water pressure as well as the momentary liquefaction in the proximity of mono-pile induced by nonlinear wave effects. Various embedded depths of mono-pile relevant for practical engineering design were studied in order to attain the insights into nonlinear wave effect around and underneath the mono-pile Foundation. By comparing time-series of water surface elevation, inline force, and wave-induced pore water pressure at the front, lateral, and lee side of mono-pile, the distinct nonlinear wave effect on pore water pressure was shown. Simulated results confirmed that the presence of mono-pile Foundation in a porous seabed had evident blocking effect on the vertical and horizontal development of pore water pressure. Increasing embedded depth enhances the blockage of vertical pore pressure development and hence results in somewhat reduced momentary liquefaction depth of the soil around the mono-pile Foundation.
Songyu Liu - One of the best experts on this subject based on the ideXlab platform.
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dynamic analysis of umbrella suction anchor Foundation embedded in seabed for Offshore wind turbines
Geomechanics for Energy and the Environment, 2017Co-Authors: Hongjun Liu, Songyu LiuAbstract:Abstract Umbrella suction anchor Foundation, a novel suction Foundation that applied to Offshore wind turbines has been proved to be a much promising potential Foundation than most of the existing Foundations including Gravity base, Monopile, Tripod, Jacket and so on. The dynamic analysis of the Offshore Foundation is more complex, comparing with the one on the land. The work presented in this paper is to conduct a comprehensive analysis on the dynamic characteristics of the umbrella suction anchor Foundation and determine its potential damage. The general finite element program ANSYS is used in the analysis. The different model vibration modes and vibration regularities of the master cylinder, the tube skirt and the anchor branches of the structure were all obtained. The structural harmonic response under loads of 0 ∼ 130 Hz was simulated and discussed. Additionally, the original structure vibration response to wave loads was analyzed based on power spectrum density (PSD) method. Both transient dynamic response process and damageable parts were thoroughly studied, after two types of random loads (seismic and ice load) were applied on the structure. Through the research, the basic dynamic responses of umbrella suction anchor Foundation to different external loads have been made clear. The results of the research will play an active and instructive role in the development of umbrella suction anchor Foundation for Offshore wind turbines.
Brendan C Okelly - One of the best experts on this subject based on the ideXlab platform.
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Offshore wind turbine structures a review
Proceedings of the Institution of Civil Engineers - Energy, 2013Co-Authors: Muhammad Arshad, Brendan C OkellyAbstract:This paper reviews various issues related to wind-power generation, one of the more popular forms of renewable energy, including attractions and challenges of electric power generation through onshore and Offshore resources. Significant increases in wind-turbine dimensions, rated power-generation capacity and size of wind farm developments over the past two decades are projected to continue. Offshore wind-power generation presents many engineering challenges including: limited guidelines available for analysis and design of Foundation/support structures; inadequate logistics for construction/fabrication; and comparatively expensive operation and maintenance costs, which combined result in current levelised cost of energy approximately double that for onshore wind-power generation. Different Offshore Foundation options are discussed in terms of general layout, loading characteristics and related fundamental natural frequency. Outlooks for some new approaches/developments and areas for further research are ...
Jisheng Zhang - One of the best experts on this subject based on the ideXlab platform.
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investigation of nonlinear wave induced seabed response around mono pile Foundation
Coastal Engineering, 2017Co-Authors: Zaibin Lin, Dubravka Pokrajac, Yakun Guo, Dongsheng Jeng, Tian Tang, Nick Rey, Jinhai Zheng, Jisheng ZhangAbstract:Abstract Stability and safety of Offshore wind turbines with mono-pile Foundations, affected by nonlinear wave effect and dynamic seabed response, are the primary concerns in Offshore Foundation design. In order to address these problems, the effects of wave nonlinearity on dynamic seabed response in the vicinity of mono-pile Foundation is investigated using an integrated model, developed using OpenFOAM, which incorporates both wave model (waves2Foam) and Biot's poro-elastic model. The present model was validated against several laboratory experiments and promising agreements were obtained. Special attention was paid to the systematic analysis of pore water pressure as well as the momentary liquefaction in the proximity of mono-pile induced by nonlinear wave effects. Various embedded depths of mono-pile relevant for practical engineering design were studied in order to attain the insights into nonlinear wave effect around and underneath the mono-pile Foundation. By comparing time-series of water surface elevation, inline force, and wave-induced pore water pressure at the front, lateral, and lee side of mono-pile, the distinct nonlinear wave effect on pore water pressure was shown. Simulated results confirmed that the presence of mono-pile Foundation in a porous seabed had evident blocking effect on the vertical and horizontal development of pore water pressure. Increasing embedded depth enhances the blockage of vertical pore pressure development and hence results in somewhat reduced momentary liquefaction depth of the soil around the mono-pile Foundation.
Hongjun Liu - One of the best experts on this subject based on the ideXlab platform.
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dynamic analysis of umbrella suction anchor Foundation embedded in seabed for Offshore wind turbines
Geomechanics for Energy and the Environment, 2017Co-Authors: Hongjun Liu, Songyu LiuAbstract:Abstract Umbrella suction anchor Foundation, a novel suction Foundation that applied to Offshore wind turbines has been proved to be a much promising potential Foundation than most of the existing Foundations including Gravity base, Monopile, Tripod, Jacket and so on. The dynamic analysis of the Offshore Foundation is more complex, comparing with the one on the land. The work presented in this paper is to conduct a comprehensive analysis on the dynamic characteristics of the umbrella suction anchor Foundation and determine its potential damage. The general finite element program ANSYS is used in the analysis. The different model vibration modes and vibration regularities of the master cylinder, the tube skirt and the anchor branches of the structure were all obtained. The structural harmonic response under loads of 0 ∼ 130 Hz was simulated and discussed. Additionally, the original structure vibration response to wave loads was analyzed based on power spectrum density (PSD) method. Both transient dynamic response process and damageable parts were thoroughly studied, after two types of random loads (seismic and ice load) were applied on the structure. Through the research, the basic dynamic responses of umbrella suction anchor Foundation to different external loads have been made clear. The results of the research will play an active and instructive role in the development of umbrella suction anchor Foundation for Offshore wind turbines.
