A new apparatus to measure time dependent shaft capacity using intact core samples

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4. A new apparatus to measure time dependent shaft capacity using intact core samples

The time dependence of pile shaft friction in fine-grained soils is well known, where the capacity gains are due to consolidation and longer-term ageing processes. While past studies have involved carrying out large-scale field tests, a more cost and time-effective approach could be to use small-scale laboratory testing. However, the use of reconstituted soil samples in the laboratory means that the potential influence of soil structure (i.e. fabric and bonding) is not captured and hence there is uncertainty in extrapolation of results to intact materials. This paper describes a new experimental set up to measure shaft friction of model piles installed in core samples of intact samples of carbonate mud retrieved from the North West Shelf of Australia. For comparison, model pile tests were performed in reconstituted samples of the same material. Similarity in the results obtained suggests that laboratory-based model pile testing can be used to assess the rate of gain of shaft friction in design from the early stages of equalisation following pile installation, through to long-term ageing. Such testing can reduce uncertainty when assessing available shaft friction at any given time such as when turbines are added to offshore wind towers or when decommissioning (removing) offshore structures.

5th International Symposium on Frontiers in Offshore Geotechnics (ISFOG2025)

7 - Pile design and installation in challenging soil conditions: glauconite, carbonated soils, cemented soils, gravels and rocks