Abstract: Considering the effects of the pile installation on the properties of the soils surrounding the piles, the load transfer models for pile shaft and pile base are established using the exponential function type load transfer curve. Then, according to the deformation mode of the soil around the piles, the stress transfer method is adopted to model the nonlinear behaviour at the pile-soil interface and the shear displacement method is used to evaluate the pile-pile interaction effects. A hybrid calculation method is proposed for assessing the nonlinear load-settlement behaviour of pile groups. The proposed method is verified by the centrifuge model test. Investigations are conducted on the effects of pile installation and nonlinear behaviour on bearing performance of pile groups. The results show that, the strength and stiffness of the soil around the piles are significantly enhanced by the pile installation due to the squeeze effects, which greatly improves the bearing performance of the pile group. The stiffness of pile-soil interface decreases with the increase of the settlement, and hence the pile group exhibits apparent nonlinear behaviour during the loading process.

Key words: pile installation effects, nonlinearity, reinforcement effect, load transfer, centrifugal model test