Wave-induced liquefaction and flow of subaqueous mud layers

Abstract

In this paper, results of laboratory experiments on wave-induced liquefaction and transport of mud are presented. Wave-induced stresses inside the bed at the onset of liquefaction are shown to be just larger than the yield strength of the bed, which is determined independently with sounding tests. After liquefaction, mud on a sloping bed starts to flow, under the combined forces of waves and gravity, with a velocity in the order of a few cm s −1. Calculations with a mathematical flow model, in which the rheological behaviour of fluid mud—obtained independently with rotational viscometers—is included, result in comparable velocities and demonstrate the effectiveness of the combination of wave and gravity forces for mud transport. Gravity provides a net downslope force and wave forces reduce the effective viscosity of fluid mud. This mechanism may be an explanation for rapid mud accumulations often observed in navigation channels after storm periods.