In this study, breaking-wave induced pore pressure response in a sandy seabed was numerically simulated by using the in-house OpenFOAM model. This paper introduces the application of a three-dimensional Finite Volume Method (FVM) model for fluid-seabed-structure interactions. First, the soil response induced by the action of breaking waves around a monopile is discussed, and then the potential of instantaneous seabed liquefaction near the pile foundation is further evaluated. Numerical examples demonstrate the free surface water elevation and the distribution of seabed liquefaction depth around piles are closely related to the hydrodynamic characteristics. Meanwhile, for the pile group system with various layouts, the hydrodynamic and dynamic seabed response characteristics are regarded as a function of pile group layout. This in turn will affect the development of the near-trapping and diffraction phenomenons.
Evaluating wave-induced seabed stability around monopile arrays is particularly important for coastal engineers involved in the design of foundation of offshore infrastructures. The physical processes involved in the whole system are rather complex, and its upper and lower structures are affected by different loads (i.e., wind, wave, current, etc.). Existing studies have shown that the influence of the seabed instability in the vicinity of the pile foundation (i.e., seabed scour, liquefaction, etc) on its bearing capacity under complex environmental loads cannot be ignored (Sumer, 2006; Jeng, 2018). However, the relationship between strong nonlinear waves such as breaking waves and the dynamic seabed response has not been clear.
On the one hand, by adopting numerical methods, the physical problems involving monopiles on the hydrodynamic wave impact (Chen et al., 2014), on-site scouring (Ahmad et al., 2018) and seabed liquefaction (Lin et al., et al. 2017) have been well discussed. On the other hand, the seabed dynamic in the vicinity of the monopile was experimentally investigated under linear waves (Wang et al., 2019) and non-linear waves (Chen et al., 2020; Zhang et al., 2020). To date, most previous studies for the wave-induced pore pressure in a porous seabed mainly focused on non-breaking regular waves (Zhang et al., 2017; Tong et al., 2018; Lin et al., 2020). Previous studies have not considered the dynamic response of pile foundations under breaking wave loading in the pertinent literature. In addition, the number of piles considered in the previous studies did not exceed four (4). However, compared to a single pile with the same solid cross-sectional area, using a group or a group of cylinders as an alternative support structure can provide more advantages (e.g., sour reduction, Backwater effect, etc.) (Yagci et al., 2017). So far, the analysis of the seabed stability of pile arrays under the action of strong breaking waves is still rare.
