Axial capacity ageing trends of large diameter tubular piles driven in sand
Cathie, D.; Jardine, R.; Silvano, R.; Kontoe, S.; Schroeder, F. (2023). Axial capacity ageing trends of large diameter tubular piles driven in sand. Soils and Foundations 63(6): 101401. https://dx.doi.org/10.1016/j.sandf.2023.101401 In: Soils and Foundations. Japanese Geotechnical Society: Tokyo. ISSN 0038-0806; e-ISSN 2524-1788, more |   |
| Keyword | | | Author keywords | Piles; Sand; Shaft capacity; Time effects; Pile driving |
| Authors | | Top | - Cathie, D., more
- Jardine, R.
- Silvano, R.
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| Abstract | The paper examines dynamic pile test data from 25 high-quality offshore cases, where end-of-initial driving (EoID) and beginning-of-restrike (BoR) instrumented dynamic monitoring was undertaken on tubular piles driven in sands at well-characterised sites after known setup periods. The static resistances derived from signal matching by two independent specialist teams using different software are com-pared with CPT-based pile capacity calculations, providing the first axial capacity and setup dataset for large offshore piles driven in sand. Complementary re-analyses are made from three onshore/nearshore sites where dynamic and static testing was conducted on com-parable piles. Open-ended tubular steel piles with 0.3-3.5 m diameters driven in (mainly dense) sands are all shown to develop marked setup, which is most active over the first 2-10 days. All piles show similar outcomes 20-30 days after installation. However, the larger diameter offshore piles' dynamic tests indicate no further setup after 30 days, while smaller diameter piles at onshore/nearshore sites con-tinue to display further marked capacity growth. Comparisons of the axial shaft capacities inferred from signal matching with CPT-based design methods provides insights into the performance of the design methods. A trend for long-term pile shaft set-up to decrease with increasing diameter is identified and ascribed principally to the diameter-dependent constrained dilatancy that develops under axial loading at the pile-sand interface. |
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