Effect of Wave Nonlinearity on the Instantaneous Seabed Liquefaction

The nonlinear variation of wave is commonly seen in nearshore area, and the resulting seabed response and liquefaction are of high concern to coastal engineers. In this study, an analytical formula considering the nonlinear wave skewness and asymmetry is adopted to provide wave pressure on the seabed surface. The liquefaction depth attenuation coefficient and width growth coefficient are defined to quantitatively characterize the nonlinear effect of wave on seabed liquefaction. Based on the 2D full dynamic model of wave-induced seabed response, a detailed parametric study is carried out in order to evaluate the influence of the nonlinear variation of wave loadings on seabed liquefaction. Further, new empirical prediction formulas are proposed to fast predict the maximum liquefaction under nonlinear wave. Results indicate that (1) Due to the influence of wave nonlinearity, the vertical transmission of negative pore water pressure in the seabed is hindered, and therefore, the amplitude decreases significantly. (2) In general, with the increase of wave nonlinearity, the liquefaction depth of seabed decreases gradually. Especially under asymmetric and skewed wave loading, the attenuation of maximum seabed liquefaction depth is the most significant among all the nonlinear wave conditions. However, highly skewed wave can cause the liquefaction depth of seabed greater than that under linear wave. (3) The asymmetry of wave pressure leads to the increase of liquefaction width, whereas the influence of skewedness is not significant. (4) Compared with the nonlinear waveform, seabed liquefaction is more sensitive to the variation of nonlinear degree of wave loading.