Dynamically Installed Anchors: Performance of embedded mooring chain profile in clay

© 2015 Taylor & Francis Group, London. Dynamically Installed Anchors (DIAs) are a recent type of mooring technology that has been shown to provide a cost-effective alternative to other forms of anchoring system in deep water sediments. For a DIA installed in soft clay, the padeye of the anchor is located significantly below the seafloor, and therefore part of the mooring chain is deeply embedded in the seabed soil. Previous investigations on the force distribution and the reverse catenary shape of the embedded mooring chain include numerical incremental analysis, theoretical closed-form solutions and laboratory tests. This paper describes the results from threedimensional Large Deformation Finite Element (LDFE) analysis undertaken to provide insight into the behavior of an embedded mooring chain profile during pullout in clay. The analyses were carried out using the coupled Eulerian-Lagrangian approach, modifying the simple elastic-perfectly plastic Tresca soil model to allow strain softening, and incorporate strain-rate dependency of the shear strength. The results were validated against theoretical (Neubecker-Randolph) solution and centrifuge test data, with good agreement obtained.