Micromechanical analysis of suction pile-granular soil interaction under inclined pulling load: Effect of pulling angle

The micro-mechanism of interaction between the suction pile and granular soil under the inclined pulling load of mooring lines remains unclear. This study investigated suction pile-soil interaction behaviour under an inclined load with different pulling angles using the coupled DEM-FEM. Discontinuity and large deformation occurrences in soil, such as voids, gaps, soil upheaval and collapse, were successfully modelled. The changes in pulling force under different pulling angles were found to stem from the suction pile-soil interaction modes. Additionally, the rotation axes of a suction pile were obtained by examining soil pressure distributions on anchor sides, and the resulting rotation angles of the suction pile were compared with each other based on these axes. The discussion includes a schematic diagram that explains the development of the rotation axes and an analysis of the shear intensity on the anchor surface. Further analysis of a series of typical particle-scale behaviours is presented, finishing with the identification of conclusive mechanical patterns of soil failure. The study suggests that neglecting the pulling angle of mooring lines can result in severely misestimating the pull-out capacity of a suction pile and misjudging the failure pattern of granular soil.