In the world of offshore wind energy, there’s a silent, unseen threat that’s been causing headaches for engineers and developers alike: scour. You know, that process where currents and waves gradually erode the seabed around the foundations of wind turbines. It’s a natural phenomenon, but it can significantly impact the stability and lifespan of these structures. Now, a recent study published in the journal ‘Applied Ocean Research’ (or ‘Applied Ocean Research’ in English) has shed some light on this issue, and it’s got some important implications for the maritime and offshore wind sectors.
The study, led by Qiang Li from Power China Huadong Engineering in Shenzhen, set out to understand how scour evolves over time and how it affects the behavior of monopile foundations—the most common type of foundation used in offshore wind farms. To do this, Li and his team conducted a series of scour inspections at a representative offshore wind farm over a one-year period. They collected high-resolution data on the geometry of the scour holes, including their depth and extent in different directions.
Based on this data, they developed an empirical model to predict how these key parameters change over time. This is a big deal because, as Li puts it, “the mechanisms and temporal evolution of offshore scour remain insufficiently understood, primarily due to the limited availability of high-resolution, long-term field monitoring data.” In other words, we’ve had a knowledge gap here, and this study is helping to fill it.
But the team didn’t stop at just understanding scour. They also wanted to know how it affects the performance of monopile foundations. To do this, they integrated their scour predictions into three-dimensional finite element models. These models incorporated an advanced soil behavior model called SANISAND-MS, which allowed them to simulate how the soil around the monopile deforms and fails under load.
What they found was striking. Scour development within the first 12 months significantly reduces foundation stiffness and capacity. In other words, the more the seabed erodes, the less stable the foundation becomes. Moreover, they found that lateral soil resistance at constant depths declines with prolonged scour exposure. This is primarily due to the loss of shallow soil volume and the associated reduction in mean effective stress. As Li explains, “these findings provide valuable insights into scour development, foundation performance, and the design of effective scour protection systems for offshore wind infrastructure.”
So, what does this mean for the maritime and offshore wind sectors? Well, for one, it highlights the importance of scour monitoring and prediction. If developers can better predict how scour will evolve at a particular site, they can design more robust foundations and scour protection systems from the outset. This could save them a lot of money in the long run, as retrofitting scour protection systems can be costly and disruptive.
Moreover, the study underscores the need for advanced soil-structure interaction models in the design of offshore wind foundations. As the offshore wind industry continues to grow and expand into deeper waters, these models will become increasingly important for ensuring the safety and reliability of wind turbines.
In the end, this study is a reminder that the seabed is a dynamic environment, and that we need to understand and account for its behavior if we’re to make the most of our offshore wind resources. As Li and his team have shown, doing so can pay significant dividends in terms of both safety and cost-effectiveness. And that’s good news for everyone involved in the maritime and offshore wind sectors.