Recruiting Institution: Ifremer – https://www.ifremer.fr/en
Contact name: Nabil Sultan – e-mail: nabil.sultan@ifremer.fr
Project and partners: BETTER project – MSCA-DN
https://www.linkedin.com/company/better-project-msca/posts/?feedView=all
Pre-requisites and mandatory documents
The position is addressed to candidate with MSc in geotechnical engineering or civil engineering
Researchers must not have resided or carried out their main activity (work, studies, etc.) in the country of the
recruiting beneficiary for more than 12 months in the 36 months immediately before their date of recruitment.
Compulsory national service, short stays such as holidays, and time spent as part of a procedure for obtaining
refugee status under the Geneva Convention1 are not taken into account. For international European research
organisations2, international organisations, or entities created under Union law, recruited researchers must not
have spent more than 12 months in the 36 months immediately before their date of recruitment in the same
appointing organisation. Note that the mobility rule applies to the (first) beneficiary where the researcher is
recruited. In case of multiple recruitments, the mobility rule only applies to the first recruitment.
Position description
The installation of foundations in gassy sediments can create pathways for gas migration or induce gas expansion
and exsolution. These processes can degrade the sediment’s mechanical properties and affect installation
procedures. Over the long term, stress fields and fluid pressure are continually disrupted by the cyclic stresses
exerted on the foundations and offshore wind structures due to waves, underwater currents, wind, and rotor
rotation. This PhD thesis focuses on addressing the influence of free gas on the mechanical properties of marine
sediments through two complementary approaches. The first approach is experimental, involving detailed
laboratory-based tests on fine clayey sediment and coarser silty sediment. The tests aim to investigate the effects
of varying gas saturation and distribution understatic and cyclic loading scenarios, simulating the installation and
operational stresses of offshore wind turbine foundations. The experimental data will be used in the second,
theoretical phase, which involves numerical simulations using advanced constitutive models that incorporate the
influence of free gas on sediment behaviours.
Expected Results:
Free gas can significantly alter the hydro-mechanical properties of marine sediment, leading to increased
compressibility, reduced shear strength, and disrupted permeability. However, its potential role as a hazard to
the foundations and structures of offshore wind turbines is often overlooked in calculation standards and
foundation design protocols. The degradation caused by the presence of free gas may occur during the
installation phase as well as throughout the operational lifespan of a wind turbine (approximately 30 years).
The main objectives of the proposed PhD thesis are:
- To experimentally characterize the effect of gas on the static and cyclic behaviour of two distinct
sediment types: fine clayey sediment and coarser silty sediment. - To evaluate the impact of gas on the installation and operational stability of two foundation types (pile
and suction anchor) in these sediment types. - To develop practical design guidelines that integrate the influence of gas into engineering practices for
offshore wind turbine foundations, thereby enhancing their reliability and performance.
Supervisors
Supervisor / PhD Director: Nabil Sultan
Co-supervisor: Patrick Mutabaruka - Employment details
The candidate will receive a three-year doctoral contract with IFREMER, in accordance with the regulations
established by the EU for MSCA fellowships. The amount is determined based on the country-specific lump sum
provided by the European funding agency, adjusted for the employer’s contribution to social insurance (see
https://www.horizon-europe.gouv.fr/sites/default/files/2025-02/french-salary-explained-pf-dn-from-2024-
pcn-2025-en–11413.pdf). The candidate will be employed by IFREMER (French Research Institute for Exploitation of the Sea). For more information, please visit the institution’s website: www.ifremer.fr
ESR specific requirements and skills
We look for a highly motivated candidate with an MSc in geotechnical engineering or civil engineering. We look for enthusiastic persons who like to work and study with other young researchers and with a particular interest to international relationships.
ESR workplace description
The workplace would be at Geo-Ocean research unit at IFREMER, located in Plouzané, France (https://www.geoocean.fr/)
About the Author
