New Method for Predicting Plug Development of Large-Diameter Steel Pipe Piles in Clay

Large-diameter steel pipe piles are widely used for both vertical and horizontal load-transfer applications, such as quay walls, offshore wind turbines, and mooring dolphins. This paper investigates the soil plug development of large-diameter steel pipe piles during penetration into clay using the coupled Eulerian–Lagrangian method. The distributions of vertical and radial stresses in the soil surrounding the pile tip during penetration are analyzed in detail. The influences of pile diameter and clay strength homogeneity on penetration resistance and plug evolution are systematically examined. The results indicate that soil plug development can be divided into three distinct stages: the initial upwelling stage, the partially plugged stage, and the approximately fully plugged stage. Compared with small-diameter steel pipe piles, the partially plugged state forms significantly earlier, while the transition to the fully plugged state is delayed. Furthermore, a new method based on radial stress analysis is proposed to predict soil plug development through data fitting. This method provides practical guidance and a valuable reference for the construction of monopile foundations in relevant engineering applications.