Suction foundation is widely used in deep sea and its ultimate bearing capacity is a key technology in offshore engineering practice

and its ultimate bearing capacity is closely related to failure modes of suction anchor at limit equilibrium state.Based on Coulomb friction theory

an exact finite element model is presented in this paper.On the basis of this FEM model

by use of the finite element analysis software ABAQUS

the effect of mooring point and aspect ratio of suction anchor on bearing capacity is researched in detail.The results shows that the ultimate bearing capacity and stability of suction anchor is affected vastly by the position of mooring point

and the variation of mooring point on suction anchor can lead to different failure modes including forward-tilted rotation failure mode

translation slip failure mode and backward-tilted rotation failure mode.