Pile set-up in sands

This paper describes the results of dynamic and static load testing at a site where open-ended steel tube piles were driven into a dense to very dense sand layer. The pile capacities on driving were significantly less than anticipated from the design calculations, with shaft resistances of 5 to 20kPa measured even at 40m depth. Later testing confirmed development of shaft resistances in excess of 160kPa. A mechanism of pile whip or flexure is hypothesized. Resistance from the internal soil column was also investigated.