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Numerical modeling of seaward tilting mechanism in vertical breakwaters

One of the most controversial failure mechanisms involved in a composite vertical breakwater is seaward tilting. Usually is believed that this failure mechanism is due to scouring or soil liquefaction induced by wave motion. However, seaward tilting might be well explained by weakening of soil due to repetitive loading. In order to give evidences for the interpretation of tilting process as weakening of soil an appropriate theoretical and numerical framework to model the foundation of marine structures is needed. The theoretical framework includes two main components. Firstly, a mathematical model to properly represent soil skeleton–pore fluids interaction based on the Generalized Biot formulation; secondly, an advanced constitutive model to reproduce the nonlinear soil behavior based on the Generalized Plasticity framework. Apart from these two main components, suitable boundary conditions are of paramount importance. The proposed theoretical framework includes, firstly, hydraulic boundary conditions to simulate the interaction between waves, sea bed and maritime structures; secondly, soil–structure interaction conditions to reproduce accurately the principal loads transmitted to the foundation, and thirdly, radiation boundary conditions to make the computational domain finite. The finite element method is adopted for the spatial discretization and the Generalized Newmark integration scheme is used for the time discretization. The proposed theoretical and numerical framework is applied to the analysis of the seaward tilt mechanism induced by the action of breaking waves over a vertical breakwater. The results numerically attained are in agreement with the main conclusions drawn from the literature associated with this failure mechanism

Author(s):

Miguel Martín Stickle    
Technical University of Madrid
Spain

Manuel Pastor    
Technical University of Madrid
Spain

Angel Yagüe    
Technical University of Madrid
Spain

Diego Manzanal    
Technical University of Madrid
Spain