Ground-Structure Interaction of Onshore Wind Turbines – Measurement and Evaluation (DFWind)
| Led by: | Prof. Dr.-Ing. Martin Achmus |
| Team: | Dr.-Ing. Khalid Abdel-Rahman, M.Sc. Oxana Bagusche, Dr.-Ing. F. tom Wörden |
| Year: | 2019 |
| Funding: | Deutsche Forschungsplattform für Windenergie (DFWind, German Research Facility for Wind Energy) |
| Duration: | 2015 – 2023 |
| Is Finished: | yes |
Description:
Wind turbines have special requirements in terms of knowledge of the interaction between the subsoil and the structure. This is due on the one hand to the fact that the effects of operation and wind are highly variable and can therefore lead to a change in the geotechnical structural response. According to the current state of knowledge, a large number of load cycles and a large cyclic load can lead to a degradation of the shear strength as well as the stiffness of the subsoil. However, it is also known that small cyclic loads can lead to an improvement in the subsoil.
For the geotechnical design of the foundation elements, EC 7 and its National Application Documents must be applied. These are supplemented by the guidelines for wind turbines issued by the Deutsches Institut für Bautechnik (German Institute for Construction Technology, DIBt). The required verifications therein are derived from the findings and experience for general application.
As part of the DF-Wind project, the aim is to determine measured values on a wind turbine that can be used to verify the general empirical values. To this end, the measurement data is collected on a real wind turbine that is founded on a pile cap. In addition to inclination and settlement measurements, the pile cutting forces are determined using fibre optic sensors. The determination of the measured values for the sub-project, which is being supervised by the IGtH, relates specifically to the following sub-aspects:
- Determination of the dynamic subsoil behaviour
- Determination of the base compressive stress distribution in a shallow foundation and its possible change over the service life
- Determination of the pile skin friction in a pile foundation and its possible change over the service life
- Determination of the skewing of the foundation structure over the service life
The measurement results allow a re-evaluation of the previous assumptions for the geotechnical design and for the overall dynamic modelling.
Sources:
DET NORSKE VERITAS: Guidelines for Design of Wind Turbines, 2nd. Ed, Kopenhagen 2002.
DEUTSCHE GESELLSCHAFT FÜR GEOTECHNIK E.V. (DGGT).: Empfehlungen des Arbeitskreises „Baugrunddynamik“. Eigenverlag: Grundbauinstitut der Technischen Universität Berlin 2002.
DEUTSCHES INSTITUT FÜR BAUTECHNIK, DIBt: Richtlinie für Windenergieanlagen. Einwirkungen und Standsicherheitsnachweise für Turm und Gründung. Fassung Oktober 2012. Schriften des DIBt, Heft 8. 2004.
DIN 1054: 2010-12: Baugrund - Sicherheitsnachweise im Erd- und Grundbau. Beuth-Verlag, 2010.
DIN EN 61400-1:2011-08: Windenergieanlagen – Teil 1: Auslegungsanforderungen. Beuth-Verlag, 2011.
QUAST, ARNE: Zur Baugrundsteifigkeit bei der gesamtdynamischen Berechnung von Windenergieanlagen, Mitteilungen des IGtH, Heft 69, 2010.
