353 - Modeling Planar Breaching of Biopolymer Treated Earthen Dams Caused by Overtopping

Research shows that biopolymers can reduce soil erodibility. It is yet unknown, however, if biopolymer-sediment mixtures can effectively increase resistance of earthen dams to breaching caused by overtopping. Laboratory experiments on planar breaching failure of untreated and biopolymer-treated sand dams were performed at the Hydraulics Laboratory of the University of South Carolina. Results show that adding biopolymer to embankment material slows down breaching of non-cohesive embankments due to erodibility reduction of treated sediment. Measurements of sediment properties, variation of dam surface elevation and breach discharge are used to parameterize and verify a one-dimensional, physics-based breach evolution model. The numerical model solves the depth-averaged flow mass and momentum equations and sediment mass conservation equation. The model is second order accurate in space and time using a predictor and corrector procedure. The model was succefully used to simulate the failure of untreated dams using flux-based sediment transport relations. Model extension to breaching of biopolymer treated dam was done with the use of a novel detachment function that was parameterized using experimental measurements.