As part of the European energy transition, offshore wind power is experiencing rapid growth.
These new giants of the seas, with blades that can reach heights of 300 metres above the water, can be installed in moderately deep waters, such as in the North Sea, using monopiles: hollow metal cylinders over 10 metres in diameter and 40 metres tall, weighing more than 1,000 tonnes, driven into the seabed to support the wind turbine mast.
However, the installation of these monopiles using hydraulic hammers is reaching its limits due to the increasing size of the piles and the noise pollution generated.
Vibro-piling is emerging as an alternative: by applying a vibration to the head of the pile, it sinks into the seabed under its own weight.
Although this technology is promising, it is still not well understood, and full-scale tests are extremely expensive.
The Geolab project enabled collaboration with the geotechnical centrifuge at Delft University of Technology (TUDelft).
This equipment allows the simulation of conditions with gravity 50 times higher than that of Earth, making it possible to conduct tests on scaled-down models under stress conditions representative of real-life situations.
Within the Institute of Mechanics, Materials and Civil Engineering, the GCE (Luc Simonin and Hadrien Rattez), CREDEM (Benoît Herman, Simon de Jaeger and Thierry Daras), and LEMSC (Alex Bertholet and Antoine Bietlot) teams have thus developed a high-frequency mini vibro-piling device capable of driving a miniature pile into a sand-filled container under 50 times Earth's gravity.
This device has been used to conduct more than 50 experiments, exploring various parameters influencing vibro-piling.
The results of these experiments will contribute to a better understanding of the underlying mechanisms, optimisation of vibro-piling parameters, and ultimately, increased reliability of this technology for offshore applications.
Picture credits
- Text thumbnail & slideshow: Pixabay - Tho-Ge
- Device : GCE-CREDEM-LEMSC