Monopile Improved Design through Advanced cyclic Soil modelling in clay (MIDASclay)

WHY

Offshore wind turbines are evolving, becoming larger and more powerful. Over the next decade, they will face more challenging marine environments and deeper waters, posing significant design and installation challenges for support structures.

Currently, about 80% of European offshore wind turbines rely on monopiles. While expected to remain a primary foundation solution, the design process involves wide safety margins, leading to excessive steel use. Since support structures comprise around 20% of wind farm investments, optimising monopile design could yield substantial cost reductions.

The MIDAS project focused on the cyclic behaviour of lateral-loaded monopiles in dense sandy soils, which is crucial for North Sea conditions. Building on this, MIDASclay aims to expand the framework and incorporate cohesive soils and soil mixtures. This results in a versatile model for simulating cyclic lateral monopile-soil interaction in diverse marine soil environments.

WHAT

MIDASclay's primary goal is to enhance understanding of monopile-soil interaction under cyclic loading in cohesive soils, developing an engineering model for fast, reliable monopile design. This will be achieved via a blend of physical and numerical modelling experimental studies.

At Deltares physical modelling laboratory, cyclic soil testing and small-scale centrifuge tests will explore cyclic monopile-clay interaction, providing novel data for numerical modelling and contributing to optimised monopile design. TU Delft researchers, supported by Deltares and the Norwegian Geotechnical Institute, will use numerical modelling to design and interpret the experiments, while PhD and Postdoc researchers at TU Delft will lead the development of a new cyclic soil reaction method for monopiles in diverse marine soil conditions.

Industry partners will test findings against relevant design cases and field data, ensuring the robustness of the proposed method. MIDASclay's methods will be tested beyond their primary scope, predicting lateral stability during the sensitive monopile installation stage, enhancing confidence in procedures and reducing costs while improving safety.

EXPECTED RESULTS

MIDASclay will yield:

• Novel experimental data characterising monopile cyclic behaviour in clay, layered soils, and mixtures.
• A unique numerical dataset from advanced simulations focusing on cyclic monopile-soil interaction.
• An improved design approach for monopiles in clay, reducing risks and uncertainties associated with cyclic loading.

By actively engaging in project development, testing, and implementation, MIDASclay partners gain a competitive edge in the offshore wind industry, leading to increased success in tenders, job creation, and overall cost reduction for global offshore wind energy. The project's benefits extend beyond partners, significantly impacting the entire offshore wind sector upon public dissemination.