2025-01-23
Building offshore windmills, and especially creating the foundation for them, is expensive and causes a great deal of impact on the environment. To improve both aspects, the SAGE-SAND project is doing research on a testing site in Zeebrugge.
The universities of Leuven, Louvain-La-Neuve and Liège received an environmental permit for a joint, temporary testing site at Zeebrugge's inner port.
There, the universities are extensively mapping the subsurface using various techniques such as soundings, drilling and geophysical tests. They then place four steel tube piles 21.5 metres long, 1.95 metres in diameter and with 21 millimetres wall thickness into the ground.
The project explores the use of vibration for the installation and removal of offshore piles or tubular piles.
The researchers place the tubular piles using two different techniques: they pile (hammer) two piles into the ground, and the other two they vibrate into the ground. Subsequently, they compare the performance of the two techniques. The researchers then measure how the soil around the piles changes.
These unique full-scale tests with extensive monitoring, advanced laboratory testing and computer modelling help create new guidelines for future projects.
The piles are also regularly tested with a lateral load test. In doing so, the researchers use a specially designed load mechanism to push sideways onto the piles, up to 10% of capacity. This is how they want to examine how that capacity changes over time.
They are also investigating seabed ageing. As such, they are researching changes in the seabed's mechanical properties over several years.
In the final testing phase, they remove the tubular piles from the ground after up to three years. Again, they will look at which technique – piling or vibrating – produces the best results.
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