Numerical analysis of bearing capacity behavior of suction caisson foundations under combined loading

As a new type of deep-water offshore foundations,suction caisson foundation is widely used in offshore engineering practice.The bearing capacity behaviour of this type of foundation under combined action of vertical pullout and horizontal force is one of the key issues in construction and design of offshore structures and facilities.However,the performance of such foundations has not been well understood and related evaluation and design method cannot meet the increasing requirement of engineering practice.Therefore a numerical procedure based on FEM for evaluating the bearing capacity behaviour of suction caisson foundation is developed in this paper.Based on the framework of the general-purpose finite element analysis software ABAQUS,both the Swipe test procedure of loading and the analysis method of fixed displacement ratio are numerically implemented.Then comparative numerical computations are performed for different combinations of the aspect ratio of caisson foundation and the reduction factor of strength of surrounding soils.The ultimate bearing capacity behaviour of caisson foundation under monotonically combined loads of vertical pullout and horizontal force is examined and the collapse envelope of caisson foundation is constituted for different combinations of vertical and horizontal components of loads.Such envelopes will be instructive in understanding the load-carrying behaviour of caisson foundations in ocean or offshore environment.