Response of Layered Seabed under Wave and Current Loading

Wen, F. and Wang, J.H., 2015. Response of layered seabed under wave and current loading.Wave and other environmental loadings in the ocean are the main factors affecting seabed stability and the safety of marine structures. Most previous literature has considered seabed response in a layered seabed under wave loading or in a single soil layer only under combined wave and current loading. In this article, a two-layered seabed, subjected to combined wave and current loading, is considered. The influence of currents on the stratified seabed response is investigated initially. The results indicate that a following current will aggravate the instability of the seabed, either in the form of liquefaction or shear failure. The effects of stratification on the seabed response were also studied. Numerical results reveal that upper layer of the seabed will become more stable as the permeability ratio (k1 : k2) increases, where k1 and k2 are the permeability of upper and lower layer of the seabed, respectively. The thickness of each layer of the seabed also affects its stability. For example, the upper layer is apt to be more unstable when the thickness of the lower layer of the seabed (h2) is equal to about one-fifth of the wave length (L/5). Analysis of the seabed reformation in relation to engineering practice shows that replacing or adding a layer onto the original seabed can both prevent liquefaction effectively, and the approach of adding a layer has the better potential to prevent liquefaction, but those treatments have a lesser effect on the maximum depth of shear failure in the original seabed.