Centre for Offshore Foundation Systems

Postgraduate profiles

Contact

Maria Coronel Uriona

Phone: (+61 8) 6488 3141


Start date

Oct 2015

Submission date

Oct 2018

Maria Coronel Uriona

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Thesis

Installation of suction caissons for offshore wind turbines in layered soils

Summary

Offshore wind energy is a proven upcoming source of renewable energy. The last 10 years have been decisive for the development of the offshore wind energy in Europe and a significative number of offshore wind farms have been planned and installed in relatively shallow waters (~ 25 to 35 m water depths), especially in the North Sea.

As wind turbines become larger in size and new wind farm developments must be erected in deeper waters than before (~ 30 to 60 m), suction buckets are being increasingly considered as an alternative cost-effective foundation concept for met masts and offshore wind turbines supported by monopiles and jackets. Already in project planning stages, the risk of geotechnical and structural installation failures must be assessed. However, the experience made to date with installation of suction buckets in the wind energy field is scarce. The installation process changes the original soil state and will therefore affect the future soil-foundation interaction. Detailed understanding and accurate prediction of suction caisson installation are therefore crucial for the in-place performance also.

In the last 30 years a considerable amount of research has been dedicated to geotechnical aspects involved in installation of suction foundations. This has been independently conducted by research institutions and oil and gas companies with focus on homogeneous soils, mainly clays. However, in the North Sea, numerous large and thick sandbanks pass through areas designated for current offshore wind farm developments and layered profiles comprising silt and clay layers are commonly found during site investigations. Suction buckets are increasingly being considered as the preferred foundation option for wind energy turbines. However, there is still a significant knowledge gap, lack of design guidelines and field experience with these soil conditions.

This research will initially revisit the available prediction approaches for suction installation in homogeneous soils, especially sand, as the current recommendations lead to such a wide range in predictions that they are unhelpful in practice. The focus of this research is the development of a method that accurately predicts the suction-assisted installation process in layered profiles, particularly the soils underlying the North Sea. The method will be based on in-situ measurements of net cone resistance from cone penetration tests (CPT), as CPTs are compulsory part of most conventional offshore soil investigation campaigns.

Why my research is important

Funding

  • Lloyd’s Register Foundation
  • UWA SIRF
  • International Living Allowance Scholarship