Wave‐Induced Effective Stress in Seabed and Its Momentary Liquefaction

The wave-induced vertical effective stress near seabed surface is approximately expressed by subtracting the pore-water pressure from the sum of the vertical static effective stress in calm water and the wave pressure acting on the seabed. Among many parameters, a ratio of the shear modulus of the solid skeleton to the effective bulk modulus of the pore-water is an important parameter to dominate the vertical effective stress and the resultant momentary liquefaction at wave trough phase. Another important parameter is a nondimensional quantity proportional to a product of the permeability coefficient and the shear modulus. As the former parameter becomes large and the latter one becomes small, a possibility that the vertical effective stress in the solid skeleton becomes zero at the wave trough phase increases. The maximum depth of being zero vertical effective stress, that is, the depth of liquefaction, is about half the wave height.