Pile Bearing Capacity under Cyclic Loading Based on Threshold Shear Strain Amplitudes

This project investigates the effects of cyclic loading on the long-term stability and serviceability of pile foundations under marine conditions. Cyclic loading—particularly from wave action and storm surges—can lead to permanent deformations and a reduction in shaft resistance when the number of load cycles is high, which may compromise the overall bearing capacity of the foundation.

To enable a reliable assessment of these effects, the threshold shear strain amplitude relevant for the soil is determined. This is a critical strain level below which the soil behaves quasi-elastically under cyclic loading and does not accumulate permanent deformations. As long as the induced strains remain below this threshold, deformation tends to stabilize ("shakedown"); if exceeded, plastic strains develop, which in extreme cases may lead to structural failure.

The threshold strain amplitudes at a specific site are determined through numerical simulations. The calculated values are then compared to the threshold shear strain amplitudes of the local soil layers to evaluate the potential for the accumulation of permanent deformations.