Characterising chalk-concrete interfaces for offshore renewable energy foundations

A. Ziogos*, M. J. Brown, A. Ivanovic, N. Morgan

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingPublished conference contribution


Deployment of renewable energy foundations, be it piles or gravity based structures, may come into contact with chalk in southern UK waters and in other parts of European offshore and nearshore deployment. To aid more appropriate design it is useful to understand the interface shear strength between the foundation and the underlying rock where this is exposed at surface or where the foundation penetrates. In this paper, the interface shear strength between chalk and unbonded concrete is investigated for constant normal stress conditions over a range of normal stresses using tilt table and specialised interface shear testing apparatus. The results show that the interface strength of chalk is significantly influenced by the normal stress used during testing where at lower stresses the interface strength exceeds the basic friction angle determined for a chalk-chalk interface and degradation of the interface strength below the basic friction angle occurs when normal stresses exceed 73% of the tensile strength of the chalk material. This degradation is more severe at small displacements than previously observed for chalk-steel interfaces. At low normal stresses and displacements, the shear strength of the chalkconcrete interface can be represented by an alpha type approach related to the chalk unconfined compressive strength as previously developed for higher strength rocks.

Original languageEnglish
Title of host publicationEngineering in Chalk
Subtitle of host publicationProceedings of the Chalk 2018 Conference
EditorsJ.A. Lawrence, M. Preene, U.L. Lawrence, R. Buckley
PublisherICE Publishing
Number of pages7
ISBN (Electronic)9780727764089
ISBN (Print)9780727764072
Publication statusPublished - 16 Aug 2018
EventChalk 2018 Conference: Engineering in Chalk - London, United Kingdom
Duration: 17 Sept 201818 Sept 2018


ConferenceChalk 2018 Conference: Engineering in Chalk
Country/TerritoryUnited Kingdom


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