Predicting monopile behaviour for the GodeWind offshore wind farm

Schroeder, Felix C.; Merritt, AS; Sørensen, Kenny Kataoka; Wood, Alastair Muir; Thilsted, C; Potts, David M.

doi:10.1201/b18442-101

Cited by 8 publications

(5 citation statements)

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“…Two distinct soil flow mechanisms can be clearly identified for the large diameter monopile, namely a wedge mechanism near the ground surface and rotational soil flow near the pile toe. Similar failure mechanisms were also observed by Hong et al [35] and Schroeder et al [39]. When considering the stress history effect, the width of the wedge failure zone on the ground surface extends from 1.6 D to 1.…”

Section: Soil Displacement Fieldsupporting

confidence: 83%

Scour Effects on the Lateral Behavior of a Large-Diameter Monopile in Soft Clay: Role of Stress History

Lai

Wang

et al. 2019

JMSE

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Scouring of soil around large-diameter monopile will alter the stress history, and therefore the stiffness and strength of the soil at shallow depth, with important consequence to the lateral behavior of piles. The existing study is mainly focused on small-diameter piles under scouring, where the soil around a pile is analyzed with two simplified approaches: (I) simply removing the scour layers without changing the strength and stiffness of the remaining soils, or (II) solely considering the effects of stress history on the soil strength. This study aims to investigate and quantify the scour effect on the lateral behavior of monopile, based on an advanced hypoplastic model considering the influence of stress history on both soil stiffness and strength. It is revealed that ignorance about the stress history effect (due to scouring) underestimates the extent of the soil failure wedge around the monopile, while overestimates soil stiffness and strength. As a result, a large-diameter pile (diameter D = 5 m) in soft clay subjected to a souring depth of 0.5 D has experienced reductions in ultimate soil resistance and initial stiffness of the p-y curves by 40% and 26%, and thus an increase of pile head deflection by 49%. Due to the inadequacy to consider the stress history effects revealed above, the existing approach (I) has led to non-conservative estimation, while the approach (II) has resulted in an over-conservative prediction.

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Section: Soil Displacement Fieldsupporting

confidence: 83%

Scour Effects on the Lateral Behavior of a Large-Diameter Monopile in Soft Clay: Role of Stress History

Lai

Wang

et al. 2019

JMSE

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“…Tests were performed on sandblasted mild steel piles with properties summarized in Table 2. The small L=D ratio is representative of modern full-scale monopiles (Sørensen et al 2017;Schroeder et al 2015), whereas the large h=D ratio is expected to be representative of operational loading conditions (Richards 2019) and ensures a rotation-dominated response. The surface is classified as smooth on the basis of the normalized roughness R n (e.g., Hu and Pu 2004), in contrast to typically rough full-scale monopiles.…”

Section: Model Pile Loading and Instrumentationmentioning

confidence: 99%

Effect of Stress Level on Response of Model Monopile to Cyclic Lateral Loading in Sand

Richards

Bransby

Byrne

et al. 2021

J. Geotech. Geoenviron. Eng.

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“…The study formed part of the PISA Joint Industry Project described by Byrne et al (2017) and Zdravković et al (2020a) which included numerical analyses and lateral loading tests on instrumented monopiles, with diameters up to 2m, at the Cowden site, that were designed to improve design for monopiles driven to support large turbines at many North and Baltic Sea glacial till offshore windfarm sites, see Schroeder et al (2015Schroeder et al ( , 2020 or Manceau et al (2019). The laboratory research described herein aimed to resolve the significant mismatch noted by Zdravković et al (2020b) between stiffness trends found from triaxial undrained compression tests on Cowden till and those inferred from field and laboratory geophysical testing and observed in the PISA pile tests.…”

Section: Introductionmentioning

confidence: 99%

Anisotropic Stiffness and Shear Strength Characteristics of a Stiff Glacial Till

Liu

Ushev

Jardine

2020

J. Geotech. Geoenviron. Eng.

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Glacial tills are widespread across North America, northern and central Asia, and northern Europe where they are also found under the Baltic, North and Norwegian Seas. Their geological and geotechnical characterisation is important to a wide range of onshore and offshore engineering projects. One aspect of tills on which little has been reported is their mechanical anisotropy. This paper reports coordinated hollow cylinder apparatus (HCA) tests, triaxial shearing and small-strain stress probing experiments, supported by index testing, on high-quality samples of a natural low-to-medium plasticity, high OCR, stiff clay-till from the Bolders Bank Formation at Cowden, near Hull in the UK. Material variability and sampling bias is inevitably introduced by the till's erratic gravel particles and fissure systems, and these aspects are addressed carefully. The experiments investigated the till's stiffness and shear strength anisotropy from its limited linear elastic range up to ultimate failure, showing that stiffnesses are higher in the horizontal direction than in the vertical and that higher undrained shear strengths develop under "passive" horizontal loading than "active" vertical loading. Comparisons are made between the till's patterns of anisotropy and those applying to previously studied sediments and reference is made to in-situ stiffness measurements. The important implications of anisotropic behaviour for geotechnical design and the interpretation of field tests are emphasised.

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Predicting monopile behaviour for the GodeWind offshore wind farm

Cited by 8 publications

References 0 publications

Scour Effects on the Lateral Behavior of a Large-Diameter Monopile in Soft Clay: Role of Stress History

Scour Effects on the Lateral Behavior of a Large-Diameter Monopile in Soft Clay: Role of Stress History

Effect of Stress Level on Response of Model Monopile to Cyclic Lateral Loading in Sand

Anisotropic Stiffness and Shear Strength Characteristics of a Stiff Glacial Till

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