Vertical field behavior of a deep large-diameter driven pipe pile in multilayered soils

Field testing was performed to examine vertical performances of a deep large-diameter driven pile used to support wind turbines in multilayered soils. The large-diameter pile was semiopen-ended and had an external diameter and length of 2.4 m and 113 m. The vertical load-displacement relationships were determined, and the shaft and base resistances were derived by analyzing segmented axial forces. The ultimate compressive capacity, determined using a modified Davisson's criterion, was 89.48 MN, which was nearly 20% and 100% larger than that estimated using the CABR JGG106-2014 (2014) criterion and dynamic load test data, respectively. The beta values obtained using the modified Davisson's criterion were slightly larger than those obtained using the CABR JGG106-2014 (2014) criterion, and the MOT JTS167-2018 (2018) results were the most conservative. Although empirical methods incorporating parameters directly interpreted from standard penetration test results provided the most consistent estimates, they are limited to some geological conditions. Appropriate coefficients were suggested for empirical methods to calculate the base resistance. The shaft resistance contributed approximately 86% of the compressive axial force. In comparison, the ultimate tensile capacity was approximately 54.58 MN when using the CABR JGG106-2014 (2014) criterion, and the shaft resistance contributed approximately 93% of the tensile force.