Context

Competitiveness, and therefore cost reduction, are hot topics for offshore wind energy players. In this context, preliminary geotechnical studies are particularly concerned because they are very expensive. They are crucial for the design of wind turbine foundations as they allow the mechanics of the seabed to be characterised. However, this type of study requires campaigns at sea with the deployment of coring machines to take soil samples which are then analysed in the laboratory. It is therefore necessary to develop alternatives to the sole use of geotechnics.

Objective

To develop a new soil characterisation methodology based on a combination of geophysical and geotechnical data in order to make recommendations for use in the offshore wind sector.

Main achievements

• New methodologies for geophysical data processing
• Multitrace seismic and electromagnetic geophysical measurement campaigns
• Design calculation of a pile from geophysical and geotechnical data
• Recommendations for the integration of geophysical data into site characterisation for project engineering

Conclusion

GEOSISMEM carried out a geophysical eabed characterisation of the Calvados offshore wind farm and the Groix & Belle-Île floating wind farm using non-conventional methods. This was compared with the geotechnical characterisation carried out by the wind farm developers prior to the projects. The data sets from both approaches were used to carry out a pile design test. The acquisition of more consistent data would make it possible to consolidate this promising approach.

Resources

GEOSISMEM fact sheet (PDF)

Partners and funding

This project was led by Université de Bretagne Occidentale and France Energies Marines.

The total project budget was €775K.

This project received funding from France Energies Marines and its members and partners, as well as French State funding managed by the National Research Agency under the Investments for the Future Programme (ANR-10-IEED-0006-27).

Photo crédit: MAPPEM Geophysics