Response of Layered Seabed under Wave and Current Loading

Abstract

Wen, F. and Wang, J.H., 0000. Response of layered seabed under wave and current loading. Journal of Coastal Research, 00(0), 000-000. Coconut Creek (Florida), ISSN 0749-0208.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 (k 1 : k 2 ) increases, where k 1 and k 2 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 (h 2 ) 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.ADDITIONAL INDEX WORDS: Porous seabed, wave and current interaction, liquefaction, shear failure, seabed protection.

Two-Dimensional Numerical Study of Seabed Response around a Buried Pipeline under Wave and Current Loading

“…Hence, in addition to wave loadings, current loadings should also be taken into consideration. Recently, numerous researchers [8][9][10][11][12] have conducted studies to understand the interaction between wave, current, and seabed. In general, to understand the phenomenon of wave-current-seabed interaction (WCSI) and wave-current-seabed-structure interaction (WCSSI), three common approaches are widely adopted, which are the analytical solution, laboratory experiments, and numerical methods.…”

Wave-Induced Seabed Response around a Dumbbell Cofferdam in Non-Homogeneous Anisotropic Seabed

“…While considering the nonlinearity of the distribution of seabed parameters, Zhou et al [37] studied the wave-induced seabed response around a pipeline buried in a multilayered seabed and the numerical results showed that pore pressure generation and liquefaction were significantly affected by the permeability of the multilayered seabed. However, the investigations that treated the vertical heterogeneous seabed as a multilayered seabed medium are valid only for uniform materials in each sublayer [38][39][40][41]. In addition, the boundary conditions used at the interface of two sublayers lead to discontinuity in some seabed responses, such as horizontal effective normal stresses, which is inconsistent with the fact that the seabed response varies continuously with depth in a natural seabed.…”

Effect of vertical seismic motion on the dynamic response and instantaneous liquefaction in a two-layer porous seabed

“…In addition, most of the previous investigations modeled seabed as uniform single layer and of either finite or infinite thickness [10,19]. In the real ocean environment, the seabed may consist of two or more layers with different soils and only a few dynamic researches attempted to treat the porous seabed as non-homogenous layered medium [20][21][22][23]. As summarized above, although the dynamic response of porous seabed has caught extensive concern, to our knowledge, the corresponding literature for the seismic response of a layered seabed has not been published to date.…”