Composite foundation or large excavation to fill thick rubble bed is always chosen when the gravity wharf is built on the soft foundation before,which will take more cost and more time.Based on the expansion project of Abidjan port in Cote d′Ivoire,the design rationality of deep water and thick replaced sand foundation is analyzed theoretically according to site condition.The site construction and the subsequent settlement and displacement development of caisson and breast wall have proved the feasibility of the construction method and the effectiveness of the treatment effect.The practice shows that the deep water and thick replaced sand foundation has the advantages of low cost,short construction period,less occupied equipment,etc.,and the vibro-compacted foundation is uniform and stable,with high bearing capacity and small settlement in the later period.This research can provide reference to the design and implementation for similar project.