Numerical Analysis of the Deformation Performance of Monopile under Wave and Current Load

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.

Soil Structure interaction of Laterally Loaded Piles

“…The above results indicate that the positive displacement corresponds to the deformation of pile head in the direction of the wave, whereas, the negative values of pile bottom deformation shows the reversal due to the moment caused by rotation of the monopile due to lateral wave loads, and that the bottom of the pile being deep in the soil bed is least affected by the wave loads. The forcedisplacement behavior of monopiles and related mechanisms for various cases are discussed in [12] The effect of wave loading and embedment length on the pile head displacements of the monopilesoil system is investigated and is observed that the displacement decreases by a factor of 8.67 % when the embedment length of the pile increases from 16 m to 20 m. However, Chen et al 2020 [13], from their comprehensive study on the deformation performance of monopiles under lateral loads, by varying the diameter of the pile and embedment depth, along with the pile wall thickness, concludes that embedment depth of the pile can contribute significantly in the reduction of pile head deflection. But under extreme environmental loading, varying the pile diameter by keeping the embedment length constant, can give improved results of lateral bearing capacity of the pile.…”

Vertical Dynamic Impedance of a Viscoelastic Pile in Arbitrarily Layered Soil Based on the Fictitious Soil Pile Model

“…Applying the separation of variables technique, substituting the single-variable function W j (r, z, s) = R j (r)Z j (z) into Equation (12) gives:…”

“…Throughout the development of the vibration theory of pile foundation, it can be seen that the pile-soil dynamic interaction models are alwaysthe main line of research regarding the vibration problems of pile foundation. In the field of the dynamic interaction between pile and PSS, there are three typical models, namely, the dynamic Winkler model [5][6][7][8][9][10][11][12][13], plain-strain model [14][15][16][17][18][19][20][21][22] and three-dimensional axisymmetric continuum model [23][24][25][26][27][28][29][30][31][32][33][34]. These models greatly promote the development of pile foundation dynamics.…”

“…The rigid model is only suitable for end-bearing piles. The second one is the elastic model (simulated by a linear spring) [12,27,37,38] or viscoelastic model (simulated by a Voigt model) [7,[9][10][11][17][18][19]21,39]. Although these models are convenient to use in engineering, the values of model parameters are mostly determined by an empirical formula, which lacks connection with the PES properties.…”

Integrity Testing of a Platform‐Pile System Using a Sensor Array and Wavenumber Domain Analysis

“…e oxidation of steel rebars, chloride-induced steel corrosion, and the resulting degradation of concrete threaten the integrity of pile systems in marine environments [4,5]. e coupled e ects of current scour and wave load can cause deformation of the pile-soil system, causing damage to the structural components (such as piles and beams) and ultimately leading to structural instability of wharves, and the changes in environmental conditions (such as geological parameters) caused by wave and current scour make pile inspections vital [6,7]. Due to the large number of overlapping re ected waves generated by complex structures, SHM with guided waves is complicated.…”