Abstract: The pile group head of jacket platforms is elastic constrained head. According to the elastic constrained head, a method to determine p-y data of jacket platform pile groups using the nonlinear foundation beam model of pile group is proposed. The lateral displacement of pile head is first determined using the pile group model with the elastic constrained head and p-y data of a single pile under total loads for the method. Additional lateral displacements due to pile group interactions are determined using Poulos’s interaction factors. The superposition result of above two calculations is taken as the initial lateral displacement of pile head of iterative calculations. The modified factor, Ym, of p-y data of the pile group associated with the first calculation is determined by calibrating p-y data of a single pile based on pile head loads and initial lateral displacement. For following calculations, p-y data of pile group associated with each iteration are determined using the updated Ym and then are used to determine the lateral displacement of pile group head and new Ym until the relative difference between Ym(i) and Ym(i-1) associate with the iterations i and i-1 is less than the tolerance. Because the method uses the p-y data considering pile group effects and the pile group model with the elastic constrained head to analyze the pile group interactions, results can objectively reflect interactions of jacket platform pile group and the deformation behavior of pile group with the elastic constrained head.

Key words: pile group analysis, pile group interaction, p-y data of pile group, modified Poulos’s method, Y-modifier