Breaching of overtopped river embankments controlled by apparent cohesion

Abstract

Laboratory experiments were conducted to obtain detailed experimental data of high temporal and spatial resolution on the breach of homogeneous non-cohesive embankments due to overtopping. These results supplement earlier data for this embankment type by providing information on the breach discharge, longitudinal and transversal breach profiles, erosion rates and pore-water pressures within the embankment. Based on detailed experimental results, two breach phases are classified. Shear and tension failure mechanisms were identified from the analysis of the obtained cross-sectional breach profiles. Furthermore, the temporal cross-sectional analysis of the used non-cohesive granular material shows a different behaviour regarding the lateral breach widening and the breach slope failure. The data analysis indicates that the apparent cohesion represented by the pore-water pressure influences the stability of the breach side slopes and hence the complete breach process. This finding is confirmed by a dimensional analysis of the experimental data and compared with information from earlier work.