Numerical Modeling of Helical Pile–Raft Foundation Systems in Offshore and Coastal Environments

The lack of competent rocky ground in coastal and offshore regions, along with ground subsidence risks, limits the effectiveness of conventional foundations on soft marine soils subjected to high loads and strict settlement criteria. This study evaluates a helical pile-raft foundation system as a hybrid solution to improve load distribution and reduce settlement. Using PLAXIS 3D finite element analysis, the influence of raft inclusion, helical pile number, arrangement, helix spacing, and plate configuration under static and cyclic loads is investigated. Results indicate that adding a raft significantly reduces settlement, while optimized configurations (three plates, 1.5–2× diameter, s/dh = 3 spacing) reduce settlement by up to 62% and increase load share by 32% without added material. These findings demonstrate the system's potential as a cost-effective, high-performance foundation for offshore and nearshore applications.