Mechanism of Wave-Induced Liquefaction and Densification in Seabed

Abstract

ABSTRACT The mechanism of the wave-induced liquefaction and densification in permeable seabed is examined with particular reference to the excess pore pressure. A concept of the ‘oscillatory’ excess pore pressure has been introduced and verified by model experiments using a newly developed apparatus. The following main conclusions are drawn from the study; 1) the oscillatory excess pore pressure is excited in the seabed where the wave-associated bottom pressure is propagated into the seabed with some damping and phase lag, 2) the magnitude of the change in the effective stress is identical with the oscillatory excess pore pressure, 3) the liquefaction and the densification occur alternately in the seabed, even in one period of the wave loading, and 4) the wave-induced liquefaction is quite different from the earthquake-induced liquefaction in the mechanism of the generation of excess pore pressures.