Experimental study on erosion of clays during rapid flows

Seabed erosion and scouring may have significant impact on the structural integrity of marine infrastructures and therefore require detailed considerations. To address this, experiments on erosion of clays were performed using a circulating flume setup, which was developed for this study. The experimental setup was designed to investigate rapid flows of up to 9 m/s. The experiments were performed on very soft to medium stiff marine clays from three different sites and on kaolin clay. The minimum bed shear stress causing erosion and the erosion rates for higher bed shear stresses were measured for the different clays. The results for the different soils showed a highly non-linear relationship between erosion rates and bed shear stresses. Different relationships were fitted to the experimental data. The relationships were: (1) between the erosion rate and bed shear stresses, (2) between the erosion threshold and the undrained shear strength and (3) between the erosion threshold and the erosion rate envelope. These general relationships gave a good fitting to the experimental data and can be used to evaluate erosion for rapid flows for cases with similar soil conditions. • A new experimental setup for erosion testing on cohesive soils was developed. • The focus on the erosion experiments was on rapid flows. • The erosion threshold and the non-linearity of the erosion rate were determined. • The experimental results were fitted with general empirical relationships.