Offshore staff
LONDON – A joint industry initiative is examining the impact of increased monopile size on the stability of wind turbine structures.
BAM, German’s Federal Institute for Materials Research and Testing, the Technical University of Berlin, and JBO are performing the Verification of Buckling Assessment and Behaviour in Large Monopiles (VERBATIM) project, with support from the Carbon Trust and the Offshore Wind Accelerator partners EnBW, Equinor, RWE, Ørsted, Scottish Power Renewables, Shell, and Vattenfall.
Work is due to be completed by early 2023.
Monopile foundations are currently the most prevalent substructures for offshore wind turbines. As the turbines increase in size, so do the supporting monopiles with diameters more than 10 m (33 ft) and lengths of over 60 m (197 ft).
But the large monopiles carry a greater risk of buckling below the seabed as the impact hammers used for installation and the forces exerted on the monopile increase. To mitigate this risk, the industry has opted for greater wall thickness.
The study will investigate how monopiles behave during installation, and the potential defects that may reduce the lifetime of an offshore wind asset, with a view to reducing wall thickness without compromising safety, while also lowering costs.
Current design practices are said to have ensured successful pile installation without pile-tip buckling or refusal, but as monopiles become larger, an enhanced design procedure is needed that prevents pile buckling.
VERBATIM is assessing potential pile-tip buckling phenomena during installation and buckling instabilities of the embedded pile near the mud-line. Its goals include developing and validating a finite element model and benchmarking study; developing a design procedure for pile embedment and stability checks; optimized pile design; and formulating technical design rules for piles.
05/24/2021
