Abstract
The research on the deformation mechanism of monopile foundation supporting offshore wind turbines is significant to optimize the design of a monopile foundation under wave and current load. In this paper, a three-dimensional wave-pile-soil coupling finite element model is proposed to investigate the deformation mechanism of monopile undercurrent and fifth-order Stokes wave. Different from the conventional assumption that there is no slip at the pile-soil interface, Frictional contact is set to simulate the relative movement between monopile and soil. Numerical results indicate that under extreme environmental conditions, the monopile foundation sways within a certain range and the maximum displacement in the loading direction is 1.3 times the displacement in the reverse direction. A further investigation has been made for a large-diameter pipe pile with various design parameters. The finite element analyses reveal that the most efficient way to reduce the deflection of the pile head is by increasing the embedment depth of the monopile. When the embedment depth is limited, increasing the pile diameter is a more effective way to strengthen the foundation than increasing the wall thickness.
Highlights
Over the past several decades, offshore wind turbines (OWT) have grown dramatically and may become an important contributor to global energy production [1]
This paper aims to propose a wave-pile-soil coupling 3D finite element model to investigate the deformation mechanism of monopile-soil system, and explore the influence of several geometrical parameters on the response of monopile foundation under extreme marine condition
The fluid model is established in Fluent 3D (ANSYS, Inc., Canonsburg, PA, USA) and solved by computational fluid dynamics (CFD); the monopile-soil model is developed in ANSYS Parametric Design Language (APDL) and solved by finite element method (FEM)
Summary
Over the past several decades, offshore wind turbines (OWT) have grown dramatically and may become an important contributor to global energy production [1]. Have conducted a 3D finite element method to analyze the performance of large-diameter monopiles Their results show that compared with API ‘p-y’ method, the 3D FEM is more accurate in studying the response of monopiles. Ma et al [14] considered the long-term effect of monopile and reflected that increasing wall thickness could lead to a remarkable decrease in deflection of pile head, but changing pile diameter did not make an obvious effect in several cases In the former studies, the calculation of wave loads acting on monopile was based on Morison’s equation which was based on the linear Airy wave theory and field test results of small-diameter monopiles [15,16]. After validating the basic model, the displacement of pile-soil system in the time domain and the effects of wall thickness, pile diameter and embedment depth on the deformation characteristics of the pile are investigated
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