Numerical testing on wave-induced seabed liquefaction with a poro-elastoplastic model

Dynamic seabed response under wave loading is one of key factors for the design and construction of offshore structures. Most previous studies were based on poroelastic seabed model. In this paper, based on a unified elasto-plastic constitutive model that can describe the liquefaction of sand and two-phase u-p theory for saturated soils, numerical tests are conducted to analyze the dynamic responses of a sandy seabed subjected to cyclic wave loads. The development of liquefaction zone, the change of excess pore water pressure (EPWP), the effective stress path, and the displacement vector are investigated. Numerical tests show that the proposed method is able to capture the mechanical behaviors of wave induced liquefaction of a sandy seabed. The calculated effective stress path and change of EPWP are similar to those of earthquake-induced liquefaction. In other words, the mechanism of wave-induced and earthquake-induced liquefaction are similar, despite of the loading forms. The liquefaction depth increases with the number of wave cycles. Meanwhile, a phase lag is observed between the liquefied seabed and wave motion. A comparison between the dynamic response of elastic and elasto-plastic seabed is presented to underline the importance of considering the plastic deformation of seabed.