The effect of over- and underestimation of predicted CPTs on the lateral response of a monopile

In offshore wind farm development, accurately predicting geotechnical parameters at unexplored sites becomes increasingly relevant for efficient site characterization and cost reduction in site investigations. This study examines the impact of over- and underestimation of predicted Cone Penetration Test (CPT) profiles on the lateral response of a monopile foundation. Utilizing geostatistical co-simulation, probabilistic CPT profiles are generated from integrated geotechnical and geophysical data, mapping intervals of prediction deviations. Findings indicate that while the predictions generally align with measured data, misestimations occur. Specifically, the underestimation of soil strength leads to a risk of unsafe designs, while overestimation may incur unnecessary costs. A simplified structural model using p-y curves assessed how these deviations influenced lateral pile behavior, with results indicating minor responses from depth intervals of 1-2 m, while influence from intervals of 5 m are significant. Generally, misestimation in the middle and lower part of the pile causes little to no changes to the limit state function for the tested depth intervals, while in in the top third a strong influence is observable.