Numerical analysis of monopiles supporting offshore wind turbines exposed to scour and cyclic loading
Numerical analysis of monopiles supporting offshore wind turbines exposed to scour and cyclic loading
Offshore wind turbines founded on monopiles are exposed to geohazards such as scour that threaten their long-term stability and serviceability. An active seabed changes the foundation conditions of these structures, which directly affects the soil-structure stiffness and its performance under environmental (cyclic) loading composed of wind and sea waves. This study aims to investigate the effects of scour under cyclic loading. A numerical approach with finite element analysis in Abaqus was applied. To simulate the long-term strain accumulation with load cycles, a hypoplastic constitutive model to reproduce the sand behaviour was implemented. Through these simulations, the ratcheting phenomenon based on increasing deformations with the number of cycles, has been simulated for sandy soils. The results quantify the effect of higher scour depths causing an increase of the displacement incremental rate per load cycle, which leads to larger maximum and residual displacements. This evidences the long-term risk for monopiles exposed to scour and cyclic loading in terms of serviceability and economic viability, due to a potential lifetime reduction given their vulnerability to excessive tilt. This study intends to raise awareness about the importance of considering scour during the design and operation of offshore wind turbines exposed to an active seabed.
C. Menendez-Vicente; S. Lopez-Querol
18th European Conference on Soil Mechanics and Geotechnical Engineering (ECSMGE2024)
E - Environment, water and energy
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