Analysis of wave-induced liquefaction of sand beds

This paper describes finite element analyses of wave-induced liquefaction of sand beds. The authors were motivated by previous experimental results in which a series of centrifuge wave tank tests were performed on loosely packed fresh deposits of sand with viscous scaling introduced. The principal finding was that the resistance to liquefaction under progressive waves was considerably smaller than the resistance exhibited under standing waves. An important factor for this marked difference was suggested to be the rotation of the principal stress axes that occurs under progressive wave loading. The present study extends an existing cyclic-plasticity constitutive model to account for the effect of stress axis rotation of sands. This model was incorporated into a finite element analysis procedure, which was applied to soil responses to progressive wave and standing wave loading. The predicted results compare well with observed soil behaviour. The predicted effective stress paths and associated stress–strain curves for the representative soil element are discussed, illustrating how the effects of rotations of the principal stress axes manifest themselves in the course of liquefaction under progressive wave loading. The prediction of the propagation of the liquefied zone is also discussed as a subject for future study.