A study on the bearing capacity of steel pipe piles with tapered tips

Abstract

The problem that occurs during open-ended steel pipe pile installation is that soil enters the pipe and develops frictional resistance that further prevents soil intrusion, causing plugging and increased piling resistance. The steel pipe pile with tapered tip (tapered tip pile) restrains plugging and piling resistance. To apply the tapered tip pile as end-supported piles, it is essential to clarify the bearing capacity mechanism suitable for tapered shapes. In addition, it is not possible to apply the bearing capacity mechanism of the flat tip pile (straight pile). The purpose of this paper is to reveal the piling performance and the bearing capacity by experiment and to propose the bearing capacity model based on the mechanism in a fully plugged mode. Experiments were conducted on model-tapered pipe piles installed in sands with different soil conditions to investigate the effects of the pile shape on piling performance and bearing capacity. Extending the combination theory of Prandtl and cavity expansion, bearing capacity model and formula incorporating shape parameters were derived. Theoretical values were good agreement with the experimental results.