Abstract

A numerical study has been carried out to investigate the effects of the wave nonlinearity on the seabed instantaneous response and liquefaction. One analytical formula considering the nonlinear wave skewness and asymmetry, is adopted to provide the wave pressure on the seabed surface. Parametric studies regarding the nonlinear effects on seabed liquefaction are conducted, in which the wave length and the wave height are involved. Results indicate (1) For asymmetric waves, nonlinear effects are more significant in the deep seabed. While for the skewed wave, it is the surface seabed that is found for the significant nonlinear effects; (2) Liquefaction depth would decrease with the increase of the wave nonlinearity; (3) The increasing wave length would weaken the effects of the wave nonlinearity on the liquefaction depth.

INTRODUCTION

Seabed response and liquefaction under periodic wave loading plays an important role in the mechanism of seabed instability, which is a great concern to the coastal scientist and engineers.

In the past few decades, numerous studies were focused on the waveinduced seabed response and liquefaction (Ulker et al., 2009). Most of them are under the assumption of linear waves. However in reality, the nonlinear wave is very commonly seen in the coastal area. When wave propagates to the shoreline, the skewed and asymmetric waves usually occur due to the wave transformation. Skewed waves mostly have a lofty crest and an even tough due to the shallow water depth (e.g., cnoidal wave). The asymmetric waves represent the waves in surf zone (e.g., saw-tooth waves with forward leaning shapes), which have a steep wave front and a gentle rear (Zhang et al., 2016). The nonlinearity is mainly reflected in the difference of surface waveform, which leads to diverse wave dynamic pressure acting on the seabed. The nonlinearity further embodies in the seabed response and liquefaction (Jeng and Cha, 2003; Chen, Huang, and Cong, 1997). However, most of the previous studies focus on some specific wave theories (e.g., Stokes and cnoidal theory) (Zhou et al., 2014; Hsu et al., 2019), which are hard to fully characterize the nonlinear wave behaviors.

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