CRITERIONS ANALYSIS ON WAVE-INDUCED SANDY SEABED TRANSIENT LIQUEFACTION

Wave-induced liquefaction of sandy seabed with loose or mediate density, directly affects the safety of marine structures. The liquefaction criterions often used in the literature are mainly based on the conception of effective stress and excess pore pressure. With analysis on physical meaning of 4 liquefaction criterions mainly used in the literature, using the analytical solution of wave-induced seabed stress and pore pressure, the distribution characteristics of transient liquefaction zone by different liquefaction criterion are compared for different computation parameters, and the suitability of the 4 liquefaction criterions is discussed. The mainly conclusions have been drawn as follows. The liquefaction criterion b, which is based on the seabed average effective stress, is not applicable to compute liquefaction of the seabed with saturation no less than 0.99 and seabed thickness no greater than 0.4 times of wave length. The liquefaction criterion d, which is based on the seabed vertical excess pore water pressure and the seabed initial mean effective stress, is not recommended in computation of liquefaction, because the liquefaction depth computed by the criterion d is obviously larger than depth of the plastic zone in most cases and the physical meaning of it is unclear. The liquefaction criterion a, which is based on the seabed vertical effective stress, and the liquefaction criterion c, which is based on the seabed vertical excess pore water pressure and the seabed initial vertical effective stress, are recommended to compute the wave-induced seabed transient liquefaction due to their good suitability.