Improved Evaluation of Interface Friction on Steel Pipe Pile in Sand

Abstract

Open-ended steel pipe piles are now widely used as the foundations for offshore structures. The pile-soil interface behavior is of particular interest in sands where shaft friction plays an important role in resisting the applied load. The rational design of the shaft capacity depends on a good understanding of the mechanisms of interface friction during pile installation and static loading. There are two new methods on the basis of the cone penetration test results that take into account the effect of friction fatigue arising from pile installation. An improvement is made in this study to account for the influence of plugging degree, which is a key issue for open-ended piles. The significance of the modified design framework lies in that it allows for the role of plugging in a more rational way by using the soil-squeezing ratio that is closely related to the radial effective stress and, consequently, the shaft capacity. The performance of the improved method is assessed against the existing methods in terms of evaluating the shaft resistance of two full-scale offshore bridge piles.