Breaching of overtopped river embankments controlled by apparent cohesion

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.