Installation and Pullout of Suction Caissons: Finite-Element Simulation

This paper reports on the development of computational tools at the Offshore Technology Research Center to study the behavior of suction caissons also known as suction anchors and bucket foundations. The effects of installation on axial capacity are examined through simulation of caisson penetration into clayey soil by self-weight and suction. A frictional contact algorithm based on a slide-line formulation is used to analyze interaction between the caisson and the surrounding soil during installation. The contact formulation allows large relative displacement between the caisson and the soil. In addition, a remeshing tool eliminates the need for a priori specification of the caisson penetration path: as installation of the caisson progresses, the finite-element mesh is adjusted so that the line of nodes below the caisson tip remains straight in the axial direction. An overview of the computational procedure along with results obtained from simulation of caisson installation, reconsolidation of the soil-skeleton and caisson pullout is presented. The computational results are compared with measurements from laboratory tests also conducted at the Offshore Technology Research Center.