This paper presents a numerical framework for monotonic and cyclic p-y curves for piles in clay, based on soil performance observed in laboratory element tests. A framework of constructing monotonic p-y curves from the stress-strain response measured in direct simple shear (DSS) tests is firstly introduced. The framework is developed from a parametric finite element study. An extension of the framework for analysing cyclic loading is then described, with the use of the cyclic accumulation procedure established at NGI in the last few decades. Finite element analyses are performed for a pile element subjected to various cyclic load parcels in order to validate the extension, using a soil model that follows the cyclic contour diagrams. The procedure to apply the proposed framework for calculating the overall pile response under monotonic and cyclic loading within a conventional beam-column type analysis is then described.
The proposed framework offers a rational approach for the p-y response of a pile element under monotonic and cyclic loading, with the possibility to consider the site specific pile-soil interface roughness, soil properties as well as the cyclic loading conditions. Finally, an example case using a program (NGI-PILE) that implements the proposed procedure is presented and validated against finite element analysis.
The currently proposed framework has potential applications for design of a range of offshore structures, including offshore well conductors, anchor piles and pile foundations supporting jacket structures.