Soutenance de thèse : Janet MODU

Physical and Numerical modeling of onshore wind turbine foundations

Doctorante : Janet MODU

Laboratoire INSA : GEOMAS

Ecole doctorale : ED162 : Mécanique, Energétique, Génie Civil, Acoustique de Lyon

In Europe, the wind energy market will change significantly between 2020 and 2030, as 50% of the existing park will be renewed. The current practice during the renewal phase, known as ‘repowering phase’, is the deconstruction of existing foundations and the reconstruction of new foundations to sustain the loads of the new wind turbine. The FEDRE FUI25 project (Fondations d'Eoliennes Durables et REpowering) therefore aims at proposing an evolutive design that allows the reuse of existing foundations. To achieve the set project objective, the current research work seeks to determine the suitability of a 1g physical model (at a scale of 1/10) for use as a tool to test the repowering solution whose verification process is coupled with numerical simulations on COMSOL Multi- physics© software. The prediction of the foundation’s behavior involves a prediction at its early age during the casting and curing phase through a 3D THC model (Thermo-Hydro- Chemical model) and at its limit states. The values obtained during the curing of the concrete were found comparable to strain values obtained in the numerical simulations of the footing under applied eccentric loading, highlighting the importance of early age prediction in concrete structures. While the laboratory model was used to further verify the THC model, different loading schemes were tested after it attained its design strength. However, since the implemented physical model is not an exact replica of the real onshore gravity foundation, only qualitative comparisons were made with in-situ measurements. Quantitative representativity of the physical model to the behavior of the real wind turbine foundation is therefore measured through numerical simulations. Upon comparison with numerical simulations, the majority of the sensor measurements of the physical model showed quite good correspondence under the given loads.