TRANSPORT OF FLUID MUD GENERATED BY WAVES ON INCLINED BEDS

Thijs van Kessel, C. Kranenburg, J.A. Battjes

Abstract


Liquefaction of a freshly deposited mud bed may occur if shear stresses in the bed, generated by wave-induced pressure gradients, locally exceed the yield strength. In this way fluid mud is generated, which has a concentration close to the original bed concentration (generally a few hundreds kg m~3). If fluid mud is displaced, very high transport rates are to be expected. This may be an explanation for rapid mud accumulations often observed in navigation channels after storm periods. In this paper waveinduced liquefaction of a sloping mud bed is investigated with laboratory experiments. A yield strength profile of the bed is obtained with a smallscale sounding test. Rheological properties of the mud after liquefaction are determined with independent rheological experiments. It is shown that calculated shear stresses in the bed at the onset of liquefaction just exceed the measured yield strength. The combination of waves and a slope turns out to be very effective for the transport of fluid mud.

Keywords


bed; inclined bed; fluid mud; mud transport

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