Scour effects on p–y curves for shallowly embedded piles in sand

Soil scour around a shallowly embedded pile can significantly compromise its lateral response, reducing both stiffness and capacity. Estimation of the lateral pile response must take into account both the scour-hole geometry and the overconsolidation effects on the remaining soil. A series of centrifuge model tests with various scour profiles were conducted at a scale of 1:250 to investigate the effects of both local and general scour on the response of a laterally loaded pile. Measured pile moment distributions and force–displacement data at the pile head were used to derive p–y curves quantifying the lateral pile–soil interaction. The p–y curves derived from various scour profiles were compared for equivalent depths below the new scour base, and below the original soil surface. For the general scour cases, the p–y curves for given depths below the post-scour surface are essentially identical to those at the same depths without scour. In contrast, for the local scour cases, the p–y response at a given depth below the scour-hole base is much stiffer than at the same depth below the original soil surface. As a practical approach to evaluate the effects of scour, the concept of an effective soil depth is introduced to determine the corresponding p–y curves for shallowly embedded piles in sand.