Numerical study for wave-induced oscillatory pore pressures and liquefaction around impermeable slope breakwater heads

The problem of wave-structure-seabed interactions (WSSI) around impermeable slope breakwater head is numerically investigated with a three-dimensional (3D) integrated model. The Reynolds-averaged Navier-Stokes (RANS) equations are adopted to simulate the wave-induced fluid motion, and Biot's theory for poro-elastic medium is employed to describe the seabed behaviour under wave loading. A calculation scheme is established to integrate both wave motion and seabed response. The numerical results reveal that wave-induced flow field in the vicinity of breakwater heads is significantly disturbed by the existence of the structure, leading to wave reflection, diffraction and overtopping. Furthermore, the wave-induced negative pore pressure and liquefaction near the front of the breakwater heads is significant. The parametric study concludes that the increase of breakwater slope intensifies the seabed response and liquefaction around the breakwater head, and therefore it is proposed to design breakwaters with a mild slope.