Numerical modelling of the breaching process in an earthen dike

Van Emelen, Sylvie [UCL] Swartenbroekx, Catherine [UCL] Zech, Yves [UCL] Soares Frazao, Sandra [UCL]

This paper presents some possible numerical approaches to describe the formation of a breach in a sand embankment. Two numerical models were applied to an experimental simplified test-case. The set-up configuration consists in a 47 cm high embankment made of homogenous non-cohesive sand. First, a classical two-dimensional shallow-water numerical model is tested to reproduce the breach growth process. This model consists in a coupled Saint-Venant-Exner model with a Meyer- Peter and Müller formula to evaluate the sediment transport rate. But this model fails in reproducing the lateral erosion during the breaching process. So a two-dimensional operator for bank failures, based on a local stability criterion accounting for the sediment critical slopes, is also applied to the shallow-water model, with the aim of improving the description of the breach formation process. The different numerical results are then compared to experimental data in order to determine the strengths and weaknesses of the last model in the simulation of a breach evolution.