<p>Surface waves may generate significant loadings on the seabed destabilizing sediments and the supporting marine structures. This threat is more pronounced in shallower water depths during long storm events in which the cyclic wave loading may induce residual pore water pressure in sediments triggering soil liquefaction. In this paper, a numerical framework is presented to evaluate the interaction of waves and horizontal sandy seabed considering nonlinear cyclic behavior of the soil. Fluid-soil interaction is captured using a coupled approach in which the continuity of pressure and flux is enforced at the interface of domains. A simple verified experimentally-driven-model is employed for concurrent simulation of nonlinear buildup of pore pressure and deformation of saturated sand subjected to the cyclic loadings. The model (in elemental scale) is incorporated into a finite element code to solve the interaction of wave and seabed (general boundary value problem). Poroelastoplastic response of the seabed is obtained by modifying the Biot’s coupled flow-and-deformation equations by adding equivalent nodal force terms associated with residual deformations of the soil at the end of each cycle. Potential flow theory is adopted for the fluid domain to model wave-induced pressure and flow fields. All governing equations and boundary conditions are solved using finite element analysis in time domain. The numerical framework is verified against results of experimental studies including cyclic triaxial compression test and wave flume experiment with soil box. Parametric studies are conducted to evaluate the effects of wave characteristics on triggering the residual liquefaction. The numerical results indicate striking agreements with experimental measures. The results also show that for large waves, progressive buildup of pore pressure in sediments may become high enough to causes significant drop in confining stresses leading to residual liquefaction. The details of the numerical model and the potential of residual liquefaction within the seabed soil are discussed.</p>

Cyclic Response and Instability Analysis of Seabed With Cohesionless Soils Due to Surging Waves

Paper Proceedings: https://asmedigitalcollection.asme.org/OMAE/OMAE2021/volume/85116

OMAE 2021

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