Cyclic behavior of XL monopole in clayey soils

PhD researcher: S. Ahayan

Promotors: F. Collin (Université de Liège), P. Kotronis (École Centrale Nantes)

Summary

Nowadays, offshore wind energy industry is developing exponentially, due to the significant contribution of the North Sea wind turbines energy production to the total consumed energy in Europe. Given that the EU's energy target is to increase the share of renewable energy by 2020, there is a great potential of the offshore wind energy applications towards this direction. In order to achieve this, the support of scientific research is crucial.

Monopiles have been by far the most common support structure for offshore turbines, nowadays becoming applicable also for complex site conditions. The current trend is towards the new generation of monopiles, called "XL monopiles", of which the diameter can reach 10 m. This allows the construction of larger turbines with high power capacity installed in deeper waters. The design tools typically applied in practice are based on the simplified p-y curve method. However, despite the wide application of monopiles in the wind sector, these tools have been evolved from the oil and gas sector based on studies of significantly thinner and slenderer monopiles than those of the wind sector.

The main objective of this project is to study the soil- foundation interaction for XL monopiles under lateral and cyclic loading, by taking into account the typical dimensions of XL monopiles. We focus, therefore, on the numerical modeling of soft clay behavior and of the soil/pile interface. We aim to develop a new constitutive law for clayey soil and a new interface constitutive model. This will allow developing new p-y curves that could be widely applied in offshore wind energy industry.