Distinct-element analysis of an offshore wind turbine monopile under cyclic lateral load

Duan, Nuo; Cheng, Y. P.; Xu, Xiaomin

doi:10.1680/jgeen.16.00171

Cited by 15 publications

(7 citation statements)

References 22 publications

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“…Also it was also found that, under the condition of 100g gravity, this series of FLAC-2D simulation data were found to match the same stress level observed in centrifuge test at 100g, will be seen in Figure 3. The detailed comparison of the numerical data and a set of centrifuge test data were shown by N. Duan (2016); N Duan and Cheng (2016); N. Duan, Cheng, and Xu (2017). The specific scaling up relationship and their potential problem will be discussed later in this section.…”

Section: Model Description 21 General Model Setupmentioning

confidence: 98%

DEM analysis of pile installation effect: comparing a bored and a driven pile

2018

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This paper presents a two-dimensional Particle Flow Code (PFC2D) model of the Discrete Element Method (DEM) that is used to study the effects of pile installation in deep foundation. It is accepted widely that installation method affects pile behaviour, but there are still limited studies that compare and analyse the impacts systematically. In this paper, the DEM is used to explain the pile behaviour installed in granular soils. A rigid bored pile and a rigid driven pile of the same geometry were installed into an assembly of granular soil modelled under a high gravitation force. Behaviour of the driven pile during penetration compares well with published data, and the numerical data also provides further insights of the soil-pile interaction during the penetration process. After pile installation, comparisons of the subsequent pile-loading behaviour were made, showing different contributions of shaft and end bearing resistance between the bored pile and the driven pile. Furthermore, the impacts of having different pile weights and different soil friction angles were discussed. When considering the same pile and soil friction, the driven pile performed better in the pile load test because the soil was compressed during the driving process. In particular, it was found that the soil friction affects the bored pile and the driven pile in a different manner such that soil friction will take effect after certain depth for bored pile, however, it will have an impact at the beginning for driven pile. Micro-scale sliding fraction of the particles near the two piles was also used to

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Section: Model Description 21 General Model Setupmentioning

confidence: 98%

DEM analysis of pile installation effect: comparing a bored and a driven pile

2018

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“…Here, we assumed that the solid phase and liquid phase are mixed perfectly in the simulation with DEM particles as theoretical representation of the soil sample that includes both soil particles and water. A total of 4,171 particles were generated following the grid-method adopted by Duan et al (2017).…”

Section: Model Set Upmentioning

confidence: 99%

Modeling of Drying‐Induced Soil Curling Phenomenon

Lin

Tang

Yang

et al. 2022

Water Resources Research

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“…Designing foundations for offshore wind turbines is challenging as: (1) these are dynamically sensitive structures in the sense that natural frequencies of these structures are very close to the forcing frequencies [1]; (2) cyclic loading can induce accumulated rotation of foundation but the tolerance for the total rotation at seabed is suggested as low as 0.5° in DNV [2]. The soil-foundation interactions under cyclic lateral loading have been investigated intensively by field tests [3], scaled model tests [4][5][6][7][8][9][10], FEM simulations [11] and DEM simulations [12,13] with majority focused on mono-pile foundations as it is the main type of foundation for offshore wind turbines. Empirical relationships for the foundation tilt or stiffness were derived from the model tests but few attention was drawn on the soil disturbances due to the limitations of monitoring technique.…”

Section: Background and Motivationmentioning

confidence: 99%

Macro- and micro-mechanics of granular soil in asymmetric cyclic loadings encountered by offshore wind turbine foundations

et al. 2019

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Offshore wind turbine foundations are subject to 10 7-10 8 cycles of loadings in their designed service life. Recent research shows that under cyclic loading, most soils change their properties. Discrete Element Modelling of cyclic simple shear tests was performed using PFC2D to analyse the micromechanics underlying the cyclic behaviours of soils. The DEM simulation were first compared with previous experimental results. Then asymmetric one-way and two-way cyclic loading pattern attained from real offshore wind farms were considered in the detailed parametric study. The simulation results show that the shear modulus increases rapidly in the initial loading cycles and then the rate of increase diminishes; the rate of increase depends on the strain amplitude, initial relative density and vertical stress. It shows that the change of soil behaviour is strongly related to the variation of coordination number, rotation of principal stress direction and evolution of degree of fabric anisotropy. Loading asymmetry only affects soil behaviours in the first few hundred of cycles. In the long term, the magnitude of (γ max − γ min) rather than loading asymmetry dominates the soil responses. Cyclic loading history may change the stress-strain behaviour of a soil to an extent dependent on its initial relative density. Keywords Discrete element modelling • Cyclic loading • Soil stiffness • Micro-mechanism Abbreviations a Parameter defining the magnitude of fabric anisotropy a max Fabric anisotropy at maximum shear strain a min Fabric anisotropy at minimum shear strain d 50 Diameter at which 50% of the sample's mass is comprised of particles with a diameter less than this value e Void ratio G Shear modulus M max Maximum moments in a load cycle M min Minimum moments in a load cycle and M ult Ultimate moment capacity N c Coordination number t Deviator stress s′ Mean stress γ max Maximum shear strain (shear strain amplitude) of a cyclic simple shear test γ min Minimum shear strain in a cyclic simple shear test ζ c Ratio of minimum moment to the maximum moment η c Parameter defined to quantify the degree of asymmetry of cyclic loading θ a Direction of the principal fabric σ Vertical stresses on the sample in a cyclic simple shear test τ max Shear stress at maximum shear strain τ min Shear stress at minimum shear strain * Liang Cui

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Distinct-element analysis of an offshore wind turbine monopile under cyclic lateral load

Cited by 15 publications

References 22 publications

DEM analysis of pile installation effect: comparing a bored and a driven pile

DEM analysis of pile installation effect: comparing a bored and a driven pile

Modeling of Drying‐Induced Soil Curling Phenomenon

Macro- and micro-mechanics of granular soil in asymmetric cyclic loadings encountered by offshore wind turbine foundations

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