Abstract

Piled foundations are often designed against static loading. However, numerous piled foundations are subjected to significant cyclic axial and lateral loads due to the wind and wave actions in their fluid environment or the rocking and swaying motions of superstructures during earthquakes, and many have failed catastrophically. Unfortunately, the response of piled foundations under live loads or in earthquakes is not yet fully understood.

In this seminar, centrifuge modelling of single piles and pile groups subjected to cyclic axial or lateral loads will be presented. The influence of cyclic loads on the performance of the bored pile and jacked pile, including the accumulated permanent displacement and the change of pile head secant stiffness, will be discussed. The interaction effect and the rocking motion of pile groups under cyclic loads will also be described. Moreover, the load transfer method is applied to simulate the axially or laterally loaded pile behaviour, and the parameter selection based on the empirical method or the finite difference method which is validated by centrifuge test results will be introduced. Finally, the response of pile groups in earthquakes modelled in centrifuge experiments will be compared with those under cyclic loads, revealing the different effects of dynamic action and pseudo-static cyclic loads. These results can offer an insight to further research to optimise construction methods and designs of piled foundations to resist live loads in service or in earthquakes.