A flume model experiment is newly developed to simulate the wave-induced liquefaction in seabed on a reduced scare of 1: 100, and examine influential factors such as the relative density of seabed on the mechanism of waveinduced liquefaction. This experiment was carried out under these conditions; the depth of water, 17cm, the wave period, 1.0s, the incident wave height, 5.5cm, the thickness of permeable layer, 35cm, and the relative density, Dr (%), 20-60. In order to satisfy similarity law in 1g gravitational field, the polymer fluid was used to change the permeability of seabed. The main conclusions obtained from this study are as follows; 1) When the relative density is about 20-40%, wave-induced liquefaction due to the increase in residual excess pore water pressure were observed in deep seabed, and shear failure due to wave force were observed in shallow seabed. 2) When the relative density is about 50-60%, wave-induced liquefaction due to the increase in residual excess pore water pressure were not observed in the present experimental condition. 3) Vertical deformation of seabed decreases with increasing density while the shape of seabed surface is similar regardless of the relative density.
