Study on combination of p-y models for laterally loaded pile in offshore wind farm

Abstract

The p-y curve method recommended by American Petroleum Institute (API) code is a mainstream design method of the laterally loaded large-diameter piles for offshore wind turbines. However, it has been long recognized that the conventional p-y models proposed for piles with a relatively large length to diameter ratio may not be appropriate for the large-diameter piles. In this study, the field tests of laterally loaded pile are analyzed in detail, particularly the bending moment and lateral displacement under multistage cyclic loading. The bending moment and lateral displacement of test pile are calculated by several combinations of clay p-y model and sand p-y model. A modified p-y model for clay is proposed considering the influence of pile diameter, and a modified p-y model for sand is proposed introducing the effect of sand layer depth and pile diameter on initial stiffness. The results indicate that the effect of pile diameter on p-y model for clay is apparent, and the influence coefficient of pile diameter on the critical parameter yc is recommended as 0.2–0.5. For the silty sand close to seabed, the formula of initial foundation stiffness of silty sand recommended by Sorensen appears to be more reasonable, and the initial foundation stiffness of silty sand at depth is suggested to calculate with formula suggested by Kallehave et al.