Abstract: The loosely deposited seabed is prone to liquefaction and other instability problems under the dynamic wave loads. Based on the highly reliable numerical coupling model FSSI-CAS 2D, the elastic-plastic constitutive model Pastor Zienkiewicz-Mark III is used to describe the complex mechanical behavior of the loose seabed. The dynamic response characteristics and liquefaction mechanism of loosely deposited seabed under conidial wave in shallow water environment are analyzed numerically. The evaluation results show that the pore water pressure of the loosely deposited seabed increases continuously at different depths, and the pore water pressure accumulation is not infinite. In some parts of the seabed soil can reach a state of complete liquefaction, becoming a heavy fluid with high viscosity. Residual liquefaction of the loosely deposited seabed under the dynamic wave loads is a gradual process that starts at the upper part of the seabed and then extends downward. The evaluation results can provide a theoretical basis for the stability analysis of seabed in offshore engineering.

Key words: Pore Pressure Accumulation, Liquefaction, Conidial Wave, Loose Seabed, Pastor-Zienkiewicz Mark III, FSSI-CAS 2D