Effect of pile arrangement on lateral response of group-pile foundation for offshore wind turbines in sand

Abstract

This study presents a series of centrifuge tests to investigate the lateral response of group-pile foundation for offshore wind turbines in ultimate conditions. The pile arrangement is specifically assessed together with the influence of pile number and soil property. The numerical analysis is conducted in ABAQUS and validated. The soil-pile interactions are demonstrated, and a parametric study is performed. The analysis shows that the axial load effect and the shadow effect simultaneously influence the behavior of the pile group. The tensile failure of the back-row pile dominates the total failure. The influence zone of the group-pile falls into 10D (D refer to pile diameter) in front of the front-row pile horizontally and 8D vertically. The front-row pile provides a majority of the lateral resistance while the contribution decreases sequentially to the very back-row. Adding rows to the pile group is more effective than adding columns to enhance the overall capacity, and the middle pile is less effective than the corner pile. A fitted formula is proposed to estimate the Pm by integrating the pile arrangement, pile number, and pile spacing. The reliability is checked against the field and centrifuge tests.