Seismological and geotechnical studies at the wind energy test site WINSENT, Germany

The Wind Science and Engineering Test Site in Complex Terrain (WINSENT) in SW Germany is a research facility to study wind energy harvesting in mountainous regions. WINSENT consists of two 0.75 MW wind turbines (WTs) along with a massive instrumentation for scientific measurements, including four 100 m high masts with numerous meteorological sensors at different heights. In addition, there are further open-field measurement systems such as remote sensing devices and a huge amount of instrumentation for nature conservation research, e.g. a bird radar and high-speed cameras for bird monitoring. For studying the soil-structure interaction, each WT foundation has six manholes for geotechnical and geophysical instrumentation such as pressure, displacement and seismic sensors inside the foundations. In addition, there are three shallow boreholes with broadband seismic sensors at 6 m depth and temporary seismic experiments are conducted to measure the propagation properties of seismic waves. These measurements are important for the safe and economic building of WTs and the understanding of the ground motion emissions from wind turbines. The results can later be used to design countermeasures at the source side and refine the determination of protection zones for seismic monitoring stations which can be disturbed from these emissions.

We present the design of the geoscientific research at WINSENT and the first results from seismic refraction measurements for local compressional and shear wave velocity models. The 3-D motion of the WT foundation was recovered: it is composed of a major tilt motion of a few micrometers and a minor wobble-type contribution. We acknowledge financial support by the German Federal Ministry for Economic Affairs and Climate Action, project WINSENTvalid, no. 03EE2028B.