2-D integrated numerical modeling for the potential of solitary wave-induced residual liquefaction over a sloping porous seabed

Abstract

A 2-D integrated numerical model is developed for liquefaction due to the build-up of pore pressure in porous sloping seabed subject to solitary wave loading. In the integrated 2-D model, the propagation of a solitary wave over a porous sloping seabed is governed using the volume-averaged Reynolds averaged Navier–Stokes equations, in which discontinuity of the flow (i.e., wave breaking due to shoaling, hydraulic jump during the wave drawdown phase) can be captured with k- ϵ model, while Biot’s consolidation equations are used for linking the solid–pore fluid interaction. Regarding the wave-induced residual soil response, a new 2-D pore pressure build-up model is developed with the new definition of the source term where the phase-resolved oscillatory shear stress is involved. The initial consolidation state of the sloping seabed foundation is considered under hydrostatic load using theory of poro-elasticity. The numerical results indicate that compared to a 1:6 slope, the wave-breaking process is more likely to occur in the case of a mild 1:15 slope due to wave shoaling and that a mild 1:15 slope experiences a longer duration of the wave run-up and drawdown compared to that in a steep 1:6 slope. Furthermore, the results suggest that the potential for liquefaction first occurs near the intersection between the initial shore line and the bed boundary. Then it will be extended both laterally and vertically to the neighboring points. The depth of the liquefaction zone increases and the width of the liquefaction zone decreases as the bed slope increases. Parametric studies indicate that the build-up of residual pore pressure can accumulate to a large value in the case of soil with lower permeability and lower relative density under larger wave loading.