Numerical Modeling of Dike Erosion Due to Overtopping Considering Downstream Slope Stability

Dike erosion modeling is mostly done for approximate computation of output discharge in order to consider measures to prevent its risks. Most of dike erosion models consist of two parts. First part includes computation of output discharge of reservoir and hydraulic modeling of water on dike’s surface. Computation of dike erosion due to overtopping using sediment transport equations is done in second part. In this study, downstream slope stability is considered in addition to two aforementioned parts. A trench is created on dike’s crest to provide initial conditions for beginning of dike gradual erosion. This model simulates increase of breach’s dimensions, output discharge increment, decrease of dike elevation and reservoir water evacuation. Output discharge is computed by broad-crested weir equation and flow hydraulic modeling is done by shallow water equations in steep slope which are descretized by McCormack method with second order of accuracy in space and time. Dike erosion computation is done by sediment continuity equation and Smart revised formula for steep slope is used to calculate sediment discharge. In order to control downstream slope of dike, several slide circular surfaces has been considered by changing center and radius of the circle and stability safety factor is calculated for each surface and the minimum is considered as the critical safety factor. If this value is less than one, slide will happen. Comparison between results of the model and experimental results and observed data revealed that the numerical model output fits well with the results of laboratory models and field tests

Keywords:

Dike erosion , Slope stability , Trench , Breach , Sediment