Abstract: The development of deep water mooring system and its mooring foundation has become a key issue in the development of clean energy "offshore wind power" projects. The drag embedment anchor, owing to its high bearing capacity and ease of installation, presents promising prospects. A prediction model for the trajectory, pitch angle and capacity of the anchor in layered soil, considering the effect of shank, is established based on the upper limit analysis. Verification of the model using existing model tests demonstrates that the trajectory prediction error of the model, accounting for the shank effect is limited to 13.5%. Furthermore, compared with the model that does not consider the shank effect, the trajectory and angle prediction error are reduced by 78.32% and 36.9% respectively. The strength, thickness and depth of stiff layer jointly restrict the embedding capability of the anchor. The influence of strength is found to be the most significant, with a higher strength ratio leading to a shallower embedding depth until the stiff layer becomes impenetrable. Additionally, greater depth is associated with increased bearing capacity. When the stiff layer can be penetrated, depth has minimal impact on trajectory and angle. However, when the stiff layer cannot be penetrated, the greater depth will result in a deeper embedment depth and smaller final angle. Lastly, the thickness of the stiff layer is found to positively correlate with the bearing capacity during the embedding process.

Key words: drag anchor, prediction model, layered soils, shank effect, trajectory