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Redemption of shaft resistance of bored piles in clay compared to Danish Code restrictions

PhD defence, Friday, 14 February 2025, Jannie Knudsen

Jannie Knudsen

During her PhD studies, Jannie Knudsen researched the complex soil-pile interaction of bored test piles in Danish Eocene clay (a stiff over consolidated and very high plasticity clay). Fibre optic based distributed line sensors were embedded in the bored test piles to allow for a more comprehensive understanding of the soil-pile interaction behaviour. Jannie Knudsen studied the mobilisation of shaft resistance for bored piles with due consideration of "locked-in" shear stresses, also known as residual stresses, originating from pile installation.


The new research findings contribute to the understanding of the non-linear load-transfer mechanisms at the interface between pile shaft and soil and present values of ultimate shaft resistance exceeding the code restrictions in the Danish national Annex to Eurocode 7, for low values of undrained shear strength.

The PhD study was completed at Department of Civil and Architechtural Engineering, Faculty of Technical Sciences, Aarhus University.

This summary was prepared by the PhD student.

Time: Friday, 14 February 2025 at 12.30.
Place: Building 3210, room 03.046, Department of Civil and Architectural Engineering, Aarhus University, Navitas, Inge Lehmanns Gade 10, 8000 Aarhus C.
Title of PhD thesis: Soil-pile interaction for bored cast-in-situ piles in stiff clays
Contact information: Jannie Knudsen, e-mail: jahs@cowi.com, tel.: +45 23626364
Members of the assessment committee:
Professor Ken Gavin, Department of Geoscience and Engineering, TU Delft, Netherlands
Director Paul Morrison, London Infrastructure Group, Arup, England, United Kingdom
Associate Professor Min Wu (chair), Department of Civil and Architechtural Engineering, Aarhus University, Denmark
Main supervisor:
Professor (Docent) Kenny Kataoka Sørensen, Department of Civil and Architechtural Engineering, Aarhus University, Denmark
Co-supervisor:
Technical Director Professor Jørgen S. Steenfelt, Department 7104.008, COWI, Denmark
Leading Specialist Helle Trankjær, Department 7104.002, COWI, Denmark
Language: The PhD dissertation will be defended in English

The defence is public.
The PhD thesis is available for reading at the Graduate School of Technical Sciences/GSTS, Jens Baggesens Vej 53, building 5221, 8200 Aarhus N.

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