Micromechanical analysis of suction bucket-granular soil interaction under eccentric pulling action of mooring lines: Effect of horizontal pulling angle

Previous suction bucket-soil interaction simulations usually apply fixed loads on suction buckets as the action of mooring lines, ignoring the contact behaviors between mooring lines and suction buckets. This study investigates suction bucket-soil interaction under the above contact behaviors with the horizontal pulling angle effect. Granular soil was generated in the DEM part while the suction buckets were simulated with meshes in the FEM part. The pulling action of mooring lines was applied by a hanger that can slide and rotate at the contact point. The micro-to-macro results revealed that the shape difference in pulling force-displacement curves can be explained by the effect of decomposed pulling actions on soil behaviors. Besides, the horizontal pulling angle effect on discontinuity and occurrences of large soil deformation can be successfully modeled by the coupled DEM-FEM method. Meanwhile, the horizontal pulling angle effect associated with different interface frictions on the movement and deformation of suction buckets were discovered. Furthermore, conclusive failure patterns of suction bucket-soil interaction were identified after analyzing particle-scale soil behaviors. The study indicates that neglecting the horizontal pulling angle of the mooring lines could result in severely misestimating the uplift capacity of a suction bucket and the soil failure pattern.