A 3D model for caisson breakwater foundations
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A 3D hydro-mechanical numerical model is presented to reproduce the behaviour of a caisson-type breakwater subjected to a storm. The model is based on the weak coupling of a Volume of Fluid (VoF) model representing the seawater and a coupled finite element model representing the concrete breakwater, the rockfill and the seabed. The first computational stage is based on the IHFOAM model that solves the three-dimensional Reynolds Averaged Navier-Stokes (RANS) equations using a finite volume discretization and the volume of fluid (VOF) method. The model is run under the action of a storm and assumes fixed displacements in the boundaries corresponding to the wet boundaries of the finite element model. As a result of this computation a series of pore pressure time histories are obtained for the aforementioned wet boundaries of the finite element model. The second computational block is based on a finite element coupled formulation implemented in the GeHoMadrid model. Computations are carried out using the pore pressure time histories obtained in the previous computational stage as hydraulic load. The concrete breakwater is modelled as a dry elastic solid. Rockfill is modelled as a two-phase saturated elastic solid. Finally, the seabed is modelled as a two-phase saturated elastoplastic solid. The Pastor-Zienkiewicz Generalized plasticity model is used for the constitutive modelling of this part of the computational domain. This constitutive modelling choice aims to represent liquefaction phenomena taking place at the seabed due to cyclic loading associated with storm action. An implicit algorithm is used for the stress integration of the Pastor-Zienkiewicz model.