Soil Resistance during Driving of Offshore Large-Diameter Open-Ended Thin-Wall Pipe Piles Driven into Clay by Impact Hammers

Abstract

To investigate soil resistance during driving (SRD) of large-diameter open-ended thin-walled piles (LOTPs) installed in clay by impact drivers, a finite element method (FEM) analysis incorporating the dynamic remeshing and interpolation technique with small strain (RITSS) was conducted. This method was verified using a field case, and its SRD was compared with that of the empirical driving formulas. The dynamic penetrations of LOTPs with three pile inner diameters (2, 4, and 6 m), and three ratios of wall thickness to pile inner diameter (1%, 1.5%, and 2%) were then numerically analyzed. The pile load-bearing performance had a significant dimensional effect, which is characterized that an increase in diameter resulting in a decrease in SRD. The LOTP shaft frictional resistances during driving was generally held in the range of around 0.3–0.5 times the undrained shear strength of the soil (Su), and it was about 6 - 8 times for the pile end resistances. The prediction equation was proposed for SRD behavior with depth, which considered the pile diameter. Then, the curves of the equation were compared with the numerical results. This study can serve as a reference for the dynamic penetration analyses of piles, including the SRD and pile-soil interaction.