As part of the energy transition and the “Climate Action Programme 2030,” a significant expansion of offshore wind energy to 25 GW is planned by 2030. This requires the use of the latest generation of wind turbines with capacities of up to 14 MW, whose foundations must be installed under strict environmental regulations. While conventional impact driving is only permissible with extensive noise reduction measures, low-emission vibratory pile driving presents an alternative. However, initial model and field tests show that the load-bearing capacity of vibrated piles is lower compared to that of driven piles. Common design methods neglect the influence of the installation process and apply an idealized “wished-in-place” assumption.

Preliminary numerical investigations by the applicants show that considering the installation process has a significant impact on the predicted load-bearing and deformation behavior of the pile after installation. This applies to both monotonic and cyclic lateral loads. This is exemplified by the back-analysis of two small-scale model tests by Le Blanc et al. (2010) on dry sand, which are documented in (Staubach et al., 2021) and summarized in Figure 1.

The goal of this research project is to develop a numerical calculation strategy that enables a realistic simulation of the entire installation process of monopile foundations. Based on the so-called “zipper-method” in combination with a high-cycle accumulation (HCA) model, the most decisive installation parameters—such as the actual installation time, frequency, load cycles, and partial drainage conditions—will be considered for the first time, while the pile-soil interaction will be modeled as accurately as possible. The developed methods will enable planning engineers and authorities to consider installation effects in the preliminary design phase and thus support the development of novel, efficient installation methods. A schematic representation of the calculation strategy is shown in Figure 2.