Seismic research conducted by Diarmid Xu, a PhD candidate at Cambridge University, is shedding light on the protection of wind turbine foundations in earthquake-prone areas. Early findings from Diarmid's study reveal intriguing patterns.His research builds upon previous studies indicating that rocks deployed around monopile offshore wind turbine foundations to prevent erosion can sink during earthquakes. Understanding the extent of rock loss is crucial to ensure continued protection for the turbines. During seismic events, a phenomenon known as seismic liquefaction occurs, causing the sand surrounding the monopiles to lose its strength. This, in turn, leads to the sinking of the rocks used as erosion prevention measures around wind farm foundations. In some cases, more than half of the rock protection disappears. Initial investigations suggest that the weight of the rock does not significantly affect its sinking depth, while the size of the rock does play a role.
The construction of wind farms in earthquake-prone zones is already underway, with plans for further expansion. Currently, the only solution for remediation involves dispatching teams on boats to assess each individual foundation and determine whether it can be salvaged.
To conduct his research, Diarmid employs geotechnical centrifuge testing. This technique involves scaling down a known foundation by a factor of 100, creating a model that can fit on a desk. The model is then subjected to testing on a massive centrifuge, accurately simulating the behavior of a real-life structure under conditions equivalent to 100 times Earth's gravity. This approach enables researchers to gain valuable insights into the response of wind turbine foundations during seismic events, aiding in the development of effective mitigation strategies.
The project is funded by HR Wallingford and EPSRC, with a collaboration between Dr John Harris and Prof Richard Whitehouse of HR Wallingford, and Prof Gopal Madabhushi of Cambridge University.
