Field experiments on instrumented winged monopiles

This paper presents the results of field tests performed to investigate the field behaviour of winged-monopile foundations. The principle of the winged monopile is that steel plates are attached to a standard monopile (in the area near the ground or seabed surface) to increase the foundation stiffness and lateral resistance. The experimental tests described in this paper consisted of load tested driven instrumented prototype scale standard (reference) monopiles and piles with varying wing geometries at two sand sites. The overall load–displacement performance and mobilised bending moment profiles were examined to assess the potential benefits of adding wings to monopiles. Experimental p–y curves were developed for the piles to analyse how the presence of wings influenced the soil– structure interaction of the foundation system. The use of simplified p–y methods for predicting the winged-pile response was assessed. The experiments proved that the addition of wings greatly improved the lateral resistance and stiffness of the piles; however, the results suggest that conventional p–y curve methods are limited as they cannot account for the effect that the enhanced stresses mobilised by the wings have on the strength and stiffness response of the pile below the wing location.