Shaft resistance of bored piles in sand

This work proposes an analytical method for the evaluation of the shaft load–settlement behaviour for bored piles in sandy soils. Key assumption is that the pile shaft response can be described through a simple law employing the initial (elastic) stiffness and the ultimate resistance. While for the first ingredient solutions provided in the literature are sufficiently accurate for engineering purposes, this work furnishes a contribution towards a more accurate evaluation of the shaft friction at failure, accounting for dilatant soil behaviour in the shear band surrounding the pile shaft. The influence of shear band thickness and shear strain at critical state is discussed, and simple rules are provided for their assessment. The effectiveness of the proposed model is checked against the results of real full-scale load tests from three well-documented case histories.