Centrifuge modelling of long term cyclic lateral loading on monopiles

A series of centrifuge cyclic monopile lateral loading experiments in dry sand are presented. Model foundation tests were performed at 100 gravities (100g) of a prototype pile 5m in diameter with an embedment depth of L/D=5. Observations indicate that permanent rotational failure criteria (θ at mudline equal to 0.25°) may not be reached for load magnitudes 40% or less of the monotonic failure load for 10⁷ cycles. A cyclic degradation model for monopile rotation accumulation is also presented. Results from the cyclic tests are used to plot contour lines of predicted rotations based on load magnitude and number of cycles applied. This model is then used to predict cyclic rotational accumulation of a load magnitude ramp test and appears to perform well.