Numerical Study of Standing Wave-Induced Seabed Residual Response with the Non-homogeneous Soil Property

Coastal seabed soil is usually non-homogeneous vertically. Seabed instability may take place under dynamic wave loading which may lead to the marine landslides. Most of the existing models have been limited to the soil oscillatory mechanism for a sandy seabed with relatively large permeability, which neglects the residual mechanism in a silt seabed with poor drainage condition. In this study, based on the Fully-dynamic (FD) seabed model, the numerical invesitgation for standing wave induced non-homogeneous seabed residual response is proposed. The present model is validated based on the flume tests in the available literatures. Good agreement between the measurements and numerical simulation is obtained. The validated model is then applied to investigate the standing wave induced pore pressure accumulation within a vertically non-homogeneous seabed. Numerical results indicate: (1) Pore pressure in the non-homogeneous seabed is much larger than that in the homogeneous seabed, of which discrepancies increase with the loading time, (2) this influence of the non homogeneous soil properties on the seabed residual response is generally larger with standing wave than that with propagation wave, and (3) the largest influence of the non-homogenoeus soil on the seabed residual response occurs at the location beneath the node of the standing wave.