Composite Modeling of the Effect of Material Composition on Spatial Dam Breaching Due to Overtopping

The overtopping of embankment dams and levees often causes erosion of embankment material, and can result in failure of the structure by breaching. The breaching process is affected by numerous characteristics of the embankment and reservoir system, including embankment geometry, material composition, and hydraulic conditions. The effects of these parameters are generally investigated by physical model experiments. The extent to which a parameter is investigated is often limited by the amount of time required for physical model setup, experimentation, and data post-processing. This study proposes a composite modeling strategy for more efficient modeling of embankment dam breaching due to overtopping. First, an embankment dam breach is modeled with physical experiments. Second, a corresponding numerical model is set up, with the same geometry, material composition, and hydraulic inputs as the physical model. Next, important findings from the physical modeling are implemented in the numerical model. Lastly, the numerical model is validated with results from the physical modeling. The composite modeling strategy was applied to an investigation of the effect of material grain size on dam breaching. The composite modeling strategy showed the ability to represent numerous effects of material grain size, including erosion rates and timing of peak outflow, as confirmed by separate physical modeling of the same system. Preliminary results indicate that the composite modeling strategy is a viable option for modeling dam breaching to investigate effects of various parameters on the breach process, allowing for greater efficiency and larger test series than with physical modeling by itself.