Impact of the solid volume fraction of clay and consolidation on the erodibility of sand-mud mixtures

The erodibility of sediment mixtures is a key factor in sediment dynamic processes and morphological evolution in coastal environments. However, it remains insufficiently understood. In the current study, the critical shear stress of sediments is analyzed with different mud contents and consolidation degrees from experimental results and previous studies. The results indicate that the critical shear stress increases with clay content, peaking at 30% clay content, and then gradually decreasing. Compared to the solid volume fraction of mud (clay and silt), the solid volume fraction of clay shows a higher relation with the critical shear stress of sand-mud mixtures. The role of the consolidation degree in the erodibility of sediment mixtures was quantified through consolidation experiments, revealing an exponential relation between critical shear stress and consolidation coefficient. An empirical equation for the critical shear stress is proposed to consider the mud content, the solid volume fraction of clay, and the consolidation degree. This equation is applicable to mixed sediment over the full range of mud content and varying consolidation degrees. It has a simple form, is easier to apply, and outperforms other empirical equations (RMSE = 0.62; R 2 = 0.73). • The solid volume fraction of clay has a greater influence on critical shear stress than the solid volume fraction of mud in sand-mud mixtures. • The influence of consolidation on erosion threshold of sand-mud mixtures is analyzed, revealing an exponential relation between the two. • A simpler and more practical empirical equation is developed to estimate the critical shear stress of sediment mixtures across the entire mud content range with varying consolidation.