Institute for Geotechnical Engineering Research Research Projects
Ho-Pile – Cyclic Extension and Experimental Validation of a p-y Approach for Sand for Safe Monopile Dimensioning

Ho-Pile – Cyclic Extension and Experimental Validation of a p-y Approach for Sand for Safe Monopile Dimensioning

Led by:  Prof. Dr.-Ing. Martin Achmus
Team:  Dr.-Ing. Khalid Abdel-Rahman, M.Sc. Junnan Song, Dr.-Ing. Florian tom Wörden
Year:  2021
Funding:  BMWi / PtJ
Duration:  01.12.2018 – 30.11.2021

Collaborative Project:

Investigations on the horizontal load-bearing behaviour of XL monopiles under cyclic loading.


Cyclical extension and experimental validation of a p-y approach for sand for safe monopile dimensioning.


In the case of a WTG monopile foundation, its steel mass depends highly on the geotechnical design. This is essentially based on p-y approaches. Due to a lack of verified knowledge, there are no clear or only insufficient specifications in the regulations. Furthermore, there are no generally accepted and experimentally validated p-y approaches available for geotechnical MP design. This leads to project uncertainties and often to unnecessary additional steel mass consumption.

The Ho-Pile research project validates and extends an existing p-y approach. This requires complex numerical FE calculations and experimental investigations on a scale of 1:5. The basis of the project is a p-y approach for sand developed in recent years. This approach is experimentally validated by tests in the foundation test pit of the TTH. Furthermore, the geotechnical MP design requires a cyclic extension of this approach. The consideration of cyclic actions on the deformation behaviour of the MP has been a research focus of the applicant in recent years. First conceptual considerations for the integration of a corresponding procedure into the static p-y approach have been developed. For this purpose, extensive numerical FE investigations have to be implemented. The results of the numerical investigations are also to be validated by experimental investigations.

For the application-orientated planning and implementation of the research project, representatives from the field will be involved in special workshops. The results of the research project will be implemented in the existing IGtH-Pile design software, which is widely used in practice, and will be made available to users free of charge. Thus, structural engineers, certifiers, inspectors, etc. can easily apply the results of this project in practice (Source: EnArgus).


  • Fraunhofer-Institut für Windenergiesysteme (IWES)
  • Testzentrum Tragstrukturen Hannover (TTH)
  • DEWI-OCC Offshore and Certification Centre GmbH, Cuxhaven
  • Bundesanstalt für Wasserbau (BAW), Hamburg