Numerical Investigation of Flow through Two Layered Rockfill Dam

Horizontal layered dams and vertical layered dams are two types of the heterogeneous rock fill dams which can are employed by many engineers for attenuation of peak discharge of flood hydrograph. In this study a two dimensional (2D) computer model has been developed to investigate the flow through two layered rock fill dams. After development of the computer model, its validation has been confirmed using experimental data. Then a series of experiments have been designed to evaluate the flow discharge through two layered rock fill dams. In these experiments, four cases of layered dam have been investigated. The results of this study indicate that in the horizontal two layered dams when the lower layer is made of the finer grained rocks, the flow discharge is less than the other arrangments. Also, in order to demonstrate the model sensitivity to grain size in each layer, a sensitivity analysis has been conducted. Also, the results indicate that in the horizontal tow layered dam for each centimeter change in the rock size of the lower layer, flow discharge changes 9.96 percent, while each centimeter change in the rock size of the top layer leads to only 4.52 percent change in the discharge. In the vertical two layered dam, for each centimeter change in the rock size of the upstream and downstream layers, the flow discharge changes 11.72 and 12.04 percent, respectively.