Design of Monopile Foundations for an Offshore Wind Farm - PISA-Study Analysis

Abstract

This master’s thesis explores the design of monopile foundations for a conceptual
offshore wind farm in the Golfo de Cádiz, Spain. It uses a one-dimensional (1D)
finite element (FE) modeling approach, based on the PISA-study. With the PISAstudy,
new design models are available, which replace the traditionally used p-y
method. A central part of this thesis is the Abaqus software, which is used to model
different 1D monopiles. These models are first validated against scenarios from the
PISA-study. Following this validation, the research investigates multiple monopile
designs, adjusting parameters like monopile length, diameter, and installation depth.
The goal is to identify configurations that minimize lateral displacements while
reducing the total weight of the monopile. The lateral displacement at groundlevel
and at different depths, where a rigid behaviour occurs, will be compared.
These results is then be used to design foundations within a wind farm, where a
15MW wind turbine from Siemens Gamesa is used. Expected loads from wind and
water on the turbines are calculated. Additionally, the thesis includes an economic
analysis covering costs related to materials and installation. While the model is
site-specific, the methodology can be adapted to similar shallow water locations in
future offshore wind projects. Overall, the findings guide future offshore wind farm
projects, highlighting how advanced modeling techniques can enhance structural
performance while delivering significant cost savings.

Popular Abstract

This master's thesis uses a one-dimensional (1D) finite element (FE) modeling approach based on the PISA-study. The main tool in this master’s thesis is the Abaqus software, which is used to model various 1D monopiles. This master's thesis focuses on variations of monopile diameter and embedded length, where diameters of 10, 12 and 16\,m and embedded lengths of 30, 45 and 60\,m are simulated. The goal is to identify configurations that minimize lateral displacements while reducing the total weight of the monopile. The lateral displacement at ground-level and at various depths, where rigid behaviour occurs, is compared.

The main advantage of a 1D model over a 3D model lies in its simplification. With the PISA-study, new design models are available, which replace the traditionally used p-y method. Geometry and input parameters can be adjusted more quickly and easily in a 1D framework. Overall, the findings guide future offshore wind farm projects, highlighting how advanced modelling techniques can enhance structural performance while delivering significant cost savings.

Today's wind turbines are significantly bigger than a few years ago and therefore new monopile designs are needed to withstand increasing loads. Expected loads from wind and water on the turbines are calculated using a 15\,MW wind turbine from Siemens Gamesa in a conceptual offshore wind farm in the Golfo de Cádiz. Additionally, this master’s thesis includes an economic analysis covering costs related to materials and installation.

The results have shown that the difference in lateral displacement between a monopile length of 45 and 60\,m is minimal, whereas the 60\,m long monopiles are significantly heavier. Although monopiles with a length of 30\,m are significantly lighter than those with a length of 45\,m, the lateral displacement is more than double or even three times as high. The final chosen geometries for the 15\,MW wind turbine have a diameter of 10 and 12\,m and an embedded length of 45\,m. Those two geometries are chosen for water depth of 20 and 30\,m. In the view of the author, these two geometries offer the best lateral displacement-to-weight ratio and can be taken into a more detailed study.

The development of a 1D model represents only an initial step in the overall design process of monopile foundations. Many further stages are required before a specific monopile geometry can be finalised for construction. These include more detailed investigations of the installation site, particularly focusing on a thorough geotechnical analysis of the ground material at the ocean floor. In addition, comprehensive environmental impact assessments must be conducted, considering not only effects on human activity but also potential disturbances to local wildlife.

• author: Garcia Kilian, Juan Miguel
• supervisor: Kent Persson
• organization: Department of Energy Sciences
• course: MVKM05 20251
• year: 2025
• type: H2 - Master's Degree (Two Years)
• subject: Technology and Engineering
• keywords: Offshore Wind Turbines, Monopile Foundations, 1D Modelling, PISA-study, Abaqus Simulation, Soil–Structure Interaction, Lateral Displacement
• report number: ISRN LUTMDN/TMPH-25/5643-SE
• ISSN: 0282-1990
• language: English
• id: 9199581
• date added to LUP: 2025-06-18 08:21:24
• date last changed: 2025-06-18 08:21:24