Experimental study of the variation of sediment erodibility under wave-loading conditions

Abstract

To obtain laboratory and in-situ measurements of the variability in the erodibility of silty sediments under wave loadings in defined bottom shear stress environments, straight flumes and annular flumes were built, tested, and deployed in the laboratory and field, respectively. In addition, wave loading simulations, geotechnical measurements, and visual observations were conducted. Results of both the laboratory and field experiments indicated that wave loadings had a significant impact on the erodibility of silty sediment, which displayed a linear reduction with an increasing magnitude and cycle number of wave loadings in laboratory simulations. However, it showed a decrease in fluctuations in field tests, and the trend in sediment erodibility was consistent with the strength parameters in response to the wave loadings. Additionally, the dynamic response of waves on the physical properties and grain size composition of the surface sediments was also found in the field experiment, which may be associated with sediment liquefaction under wave loadings and could be considered an internal agent for the variation in sediment erodibility and strength under dynamic conditions. Finally, comparisons between laboratory and field experiments revealed that sediment in different states had different failure patterns under wave loadings, and erodibility of the same sediment had a different sensitivity to wave loadings in a different range of magnitudes.