Centrifuge model tests on anchor pile of single point mooring system under oblique pullout load using transparent sand

Single point mooring system anchored by piles has been widely used to support floating offshore platforms. However, the failure mechanism and soil displacement of the anchor pile subjected to oblique pullout loads are still unclear. Based on transparent sand and PIV technique, a visual centrifuge test system for anchor piles of single point moorings was established. A series of centrifuge model tests were performed on the pile under oblique pullout loads, and the measured soil displacement field results were compared with the finite element simulation, indicating that the centrifuge modeling using transparent sand are suitable for studying the anchor pile behaviors and soil deformation. A modified semi-empirical method was also proposed, which can predict the bearing capacity of piles under difference loading angle and loading position in sand. It shows that with the increasing loading angle and pad eye depth, the pile horizontal translation and soil horizontal deformation become more obvious, and the pullout bearing capacity increases. The proportion of the soil horizontal displacement for theta = 75 degrees is nearly 4.1 times of that for theta = 37 degrees, and the horizontal displacement proportion for z = 0.75L increases approximately 25% of that for z = 0.67L.