Abstract
The excess pore pressures and effective stress variations in a porous seabed are measured at a breaker zone in real ocean environment. The wave-induced liquefaction is examined on the basis of the liquefaction criterion proposed by the authors. The oscillatory pore pressure, which is one of the dominant factors causing the wave-induced liquefaction, is theoretically estimated to compare with the observed data. The major conclusions drawn from the study are : (1) The effective stress in the seabed varies periodically in accordance with the propagation of ocean waves, (2) The variation of the vertical effective stress is expressed by the difference between the wave-associated bottom pressure and the oscillatory pore pressure in the seabed, (3) The oscillatory pore pressure induced by the irregular waves can be estimated by the equation proposed by the authors, (4) The liquefaction potential in the seabed can be evaluated on the basis of the proposed liquefaction criterion, (5) The wave-induced liquefaction is closely related to the upward seepage flow induced in the seabed by the rapid lowering in the sea surface during the passage of wave trough.
