Open ended steel piles, driven by underwater impact hammers, are used offshore for a range of subsea applications, including pipeline initiation, hold-down and hold-back anchors, subsea structures and platform piles, amongst others. The pile driveability analysis of such piles is a critical part of the overall pile design process to ensure that the selected installation hammer has sufficient power to drive the piles to depth and that the dynamic stresses and fatigue damage in the pile during driving are within acceptable limits. The pile driveability assessment also has to ensure that pile free-fall is not a risk, which can be an issue in certain soils (carbonate soils for example).
Accurate prediction of pile driveability, however, remains a considerable challenge, especially when faced with complex soil conditions. This paper presents pile driving records from six recent different offshore campaigns (16 pile driving records) covering a range of subsea applications using piles with varying pile properties, subsea hammers, geographical locations and soil conditions.
These pile driving records have been back-analysed with the appropriate as-installed hammer efficiencies in order to assess the accuracy of existing Static Resistance to Driving (SRD) models to predict the hammer blow counts. The use of a more recent static capacity formulae (UWA-05) to predict driveability is also considered.
