Abstract
Previous studies on wave-induced pore pressure in a porous seabed mainly focused on non-breaking regular waves, e.g., Airy linear waves or Stokes non-linear waves. In this study, breaking-wave induced pore pressure response in a sandy seabed was physically simulated with a large wave flume. The breaking-wave was generated by superimposing a series of longer waves onto the foregoing shorter waves at a specified location. Water surface elevations and the corresponding pore pressure in the process of wave breaking were measured simultaneously at three typical locations, i.e., at the rear, just at, and in front of the wave breaking location. Based on test results, characterization parameters are proposed for the wave surface elevations and the corresponding pore-pressures. Flume observations indicate that the wave height was greatly diminished during wave breaking, which further affected the pore-pressure responses. Moreover, the measured values of the characteristic time parameters for the breaking-wave induced pore-pressure are larger than those for the free surface elevation of breaking-waves. Under the action of incipient-breaking or broken waves, the measured values of the amplitude of transient pore-pressures are generally smaller than the predicted results with the analytical solution by Yamamoto et al. (1978) for non-breaking regular waves with equivalent values of characteristic wave height and wave period.
Highlights
Numerous failures of subsea structures have been reported as a result of the waveinduced seabed liquefaction or the reduction of soil strength of the seabed, e.g., lateral instability, sinking/uplifting of submarine pipelines [1,2,3,4], and instability of various types of offshore foundations [5,6,7,8,9]
The wave‐breaking is a common scenario in coastal surf zones, which may further influence the pore‐pressure responses in the porous seabed
The following conclusions can be drawn from the flume observations
Summary
Numerous failures of subsea structures have been reported as a result of the waveinduced seabed liquefaction or the reduction of soil strength of the seabed, e.g., lateral instability, sinking/uplifting of submarine pipelines [1,2,3,4], and instability of various types of offshore foundations [5,6,7,8,9]. Since the 1970s, wave induced pore-pressure responses in a porous seabed have been investigated intensively, including analytical predictions [10,11,12], numerical modeling [13,14,15], and experimental observations [16,17,18]. Jeng and Zhang [35] employed an integrated threedimensional poro-elastic model to evaluate the breaking-wave induced seabed liquefaction potential with a case study on the surf zones at Gold Coast in Australia Their numerical results showed that the magnitude of pore pressures in the seabed under non-breaking waves is slightly greater than that under breaking-waves due to the effect of wave energy dissipation, which affects the corresponding liquefaction depth.
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