Sequential Evolution of Residual Liquefaction in a Silty Seabed: Effect of Wave-Loading History

Abstract

Multiple liquefaction events may occur if a seabed is subjected to repeated but intermittent wave loadings. This study aimed to investigate the influence of the wave-loading history on the evolution of residual liquefaction in a silty seabed through a series of wave flume tests. The flume observations reveal that the preceding wave-loading history results in the densification of the silt bed and a noticeable settlement of the mudline. Meanwhile, the ultimate liquefaction depth, maximum amplitude of interfacial waves, and mudline settlement decrease due to prior wave actions. Both the maximum residual pore pressure ratio and the amplification ratio of transient pore pressure exhibit a declining trend with an increasing number of wave exposures, indicating that the liquefaction resistance of the soil is obviously enhanced. Throughout the continuous liquefaction stage, the residual pore pressure in liquefied soil regions maintains its maximum value. In contrast, the pore pressure in the un-liquefied soil layer experiences slight dissipation after reaching its peak during wave activity. Moreover, the reshaped topography of the silt bed following liquefaction-densification cycles may serve as an indicator of prior liquefaction events, transforming from mud volcanoes into ripples as the liquefaction depth decreases.