Installation effects in the response of laterally loaded monopiles in sand- a numerical-based analysis

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4. Installation effects in the response of laterally loaded monopiles in sand- a numerical-based analysis

The rate of construction of offshore wind turbine farms is continuously increasing, with monopiles being the extended type of foundation. During the life period of these infrastructures, the offshore environment induces lateral loads, which are transmitted to the soil. This repetition of the lateral forces results in accumulated deformations in the foundation. Thus, after a certain point of residual displacements, the operation of the wind turbine is compromised, as the serviceability limit state is exceeded. Hence, the research efforts need to focus on the cyclic effects taking place on a large-piled foundation. But for the sake of completeness, it should be stressed that in monopiles, the properties of the soil mass control the response. Different aspects affect the rate of accumulated displacements of monopiles in cohesionless soils, but one of the most important effects is the disruption of the initial soil conditions during their installation. This paper aims to investigate the long-term cyclic response of monopiles taking into consideration the installation effects. In view of such calculations, advanced Finite Element Method (FEM) modelling, adopting the hypoplastic law with intergranular strain, is undertaken in this paper.  For the calculation of the lateral cyclic response, an elasto-plastic, stiffness degradation model is considered. Herein, the soil state condition after installation is presented, while afterwards a comparative response analysis between jacked and wished in place piles is carried out.

10th European Conference on Numerical Methods in Geotechnical Engineering (NUMGE2023)

12. Offshore geotechnics