Closed-form stiffnesses of multi-bucket foundations for OWT including group effect correction factors

Bordón, Jacob D.R.; Aznárez, Juan J.; Padrón, Luis A.; Maeso, Orlando; Bhattacharya, Subhamoy

doi:10.1016/j.marstruc.2019.01.008

Cited by 12 publications

(10 citation statements)

References 22 publications

(32 reference statements)

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“…These factors are interesting not only because they measure the intensity of the foundation-soil-foundation interaction, but because they can be approximated by closed-form formulas. Approximate group effect stiffness correction factors γ have been presented in an earlier work [Bordón et al, 2019]. They were obtained via curve fitting of numerical results, and they consider tripod, tetrapod, pentapod and hexapod arrangements of rigid buckets up to L/D ≤ 1 in homogeneous soils.…”

Section: Methodsmentioning

confidence: 99%

“…It is also shown three different slenderness cases: L/D = 0 (surface foundation or suction caisson with a very flexible skirt), L/D = 1 (embedded foundation or typical suction caisson with rigid skirt in sand soils) and L/D = 4 (moderately deep foundation or typical suction caisson with rigid skirt in clay soils). Solid lines correspond to results obtained from a Boundary Element model (BE) [Bordón et al, 2017, Bordón et al, 2019, while dashed lines correspond to results of the proposed Simple Approach (SA). The following discussion is based on the results shown in these figures.…”

Section: Homogeneous Soilmentioning

confidence: 99%

“…Helping effects tend to reduce the resulting stiffness (like in the vertical and horizontal case), and vice versa for non-helping effects. In [Bordón et al, 2019], a qualitative description of these effects are given. In the present paper, all these effects are quantified by some of the components of the complete 6 × 6 Green's function matrix (see Appendix B).…”

Section: Homogeneous Soilmentioning

confidence: 99%

“…6to the foundation nodes of the superstructure. 7 Three-dimensional BE-FE model [Bordón et al, 2017, Bordón et al, 2019 Table 1: Description of models considered in the usage example…”

Section: Non-homogeneous Soilsmentioning

confidence: 99%

“…The intermediate models increasingly removes the amount of limiting hypothesis such as the foundation-soil-foundation interaction and the master node rigidly connected to foundation nodes. Models from 1 to 6 are built in a in-house standard finite element code, while model 7 is built using a boundary element -finite element code developed by the authors [Bordón et al, 2017, Bordón et al, 2019. In the latter case, the use of the Mindlin's Green's function reduces the discretisation to only the soil-foundation interface, and thus it incorporates the unbounded domain (half-space) in an exact manner.…”

Section: Usage Examplementioning

confidence: 99%

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Simple approach for including foundation–soil–foundation interaction in the static stiffnesses of multi-element shallow foundations

et al. 2021

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In common engineering practice, foundation-soil-foundation interaction of shallow foundations is frequently ignored. This is presumably due to cost/benefit reasons since computationally demanding finite and/or boundary element models are required for that purpose, and its effects are usually assumed as negligible. In this sense, the present paper provides a simple and inexpensive way of incorporating foundation-soil-foundation interaction through a numerically explicit stiffness matrix formulation. The necessary ingredients for homogeneous and non-homogeneous (shear modulus power-law variation with depth) half-spaces are given. The proposed approach is then applied to offshore wind turbines multiple suction caisson foundations (tripod and tetrapod), where it is observed that foundation-soilfoundation interaction is significant. Its range of validity is also established, and valuable ready-to-use closed-form formulas for the correction factors of the stiffnesses of tripod and tetrapod groups are also derived. The methodology is applicable as long as the spacing between foundations is somewhat greater than foundation depth.

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Section: Methodsmentioning

confidence: 99%

Section: Homogeneous Soilmentioning

confidence: 99%

Section: Homogeneous Soilmentioning

confidence: 99%

“…6to the foundation nodes of the superstructure. 7 Three-dimensional BE-FE model [Bordón et al, 2017, Bordón et al, 2019 Table 1: Description of models considered in the usage example…”

Section: Non-homogeneous Soilsmentioning

confidence: 99%

Section: Usage Examplementioning

confidence: 99%

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Simple approach for including foundation–soil–foundation interaction in the static stiffnesses of multi-element shallow foundations

et al. 2021

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A theoretical and practical framework based on plasticity theory for the drained behavior of single and multiple shallow footings

Barari

Zhou

Ibsen

et al. 2023

Num Anal Meth Geomechanics

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With the shift of the offshore wind energy sector to deeper waters, demand for the development of more complex foundation solutions, particularly suction bucket – supported tripod/tetrapod and jacket foundations, has increased. This paper is divided into two main sections. The first part comprises a comprehensive review of the performance of circular surface and shallow foundations under combined loading (VHM), and how it can principally be understood in a theoretical framework of plasticity theory. Examination of the considered data suggested that the general assumption of over‐estimated non‐association degree with constant failure surface parameters and increasing vertical load may require further investigation. This may be attributed to the complex interplay of multiple properties such as stress level, soil strength profile and foundation geometry. The existing data in the literature were also used to provide practical guidance for a successful implementation of the elasto‐plastic constitutive relationships in offshore foundation design. In second part of the paper, the suitability of the non‐associated plasticity formulation for a baseline multi‐pod system in H‐M load space was investigated using three‐dimensional (3D) finite element (FE) analyses and not verified. Furthermore, the failure envelopes and hardening law for caissons with different embedment ratios differed from those recommended in the literature were established. Parametric studies of multi‐caisson foundations revealed that the failure mechanism of multi‐bucket foundations under horizontal loading depended greatly on the bucket spacing. The horizontal bearing capacities increased with the bucket spacing until they reached a threshold. Meanwhile, analyses of the multi‐bucket foundation under moment loading confirmed the occurrence of a push‐pull failure mechanism.

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A simplified approach to account for through-soil interaction between two adjacent shallow foundations

Zeolla¹,

Silva²,

Sica³

2023

Bull Earthquake Eng

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Closed-form stiffnesses of multi-bucket foundations for OWT including group effect correction factors

Cited by 12 publications

References 22 publications

Simple approach for including foundation–soil–foundation interaction in the static stiffnesses of multi-element shallow foundations

Simple approach for including foundation–soil–foundation interaction in the static stiffnesses of multi-element shallow foundations

A theoretical and practical framework based on plasticity theory for the drained behavior of single and multiple shallow footings

A simplified approach to account for through-soil interaction between two adjacent shallow foundations

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