Seite - 1541 - in Book of Full Papers - Symposium Hydro Engineering

the river diversion tunnel design it should be noted that in the river diversion through this structure, the flow depth should progress to uniform depth. Thus, it is necessary to define under which conditions the flow is to proceed along the diversion tunnel. Therefore, it is possible to conclude the existence of hydraulic jumps inside the tunnel and determine its location. Studying the flow conditions inside the tunnel consists of analyzing the flow depths along the tunnel by defining the backwater curves. Thus, it is important to trace the backwater curves for diversion tunnel with the goal of establishment the various flow depths along the structure allowing the flow classification. Flow conditions in tunnel: The occurrence of hydraulic jumps inside the river diversion tunnel can cause structural problems. By establishing the different depths inside the tunnel, it is possible to determine the amount of total movement inside it and the hydraulic jump position. Knowing the flow depths is very important in the study of the river diversion tunnel, so it is imperative to establish backwater curves inside the tunnel. This computation is based on the Bernoulli's theorem. Free surface flow: In most cases, flow takes place in free surface and should not exceed 70% of the tunnel capacity. When deploying a river diversion with pressure flow, it must be ensured that the structure’s altimetry track allow the respective domes to always be situated below the isometric line to avoid depressions that may cause structural and hydraulic inconvenient. The study of flow through the tunnel is hampered by the tunnel geometry. The tunnel cross section assumes generally circular or horseshoe geometry. In case of using a river diversion tunnel is possible to convert it in the bottom discharge of the final structure. This approach has advantages, especially in project costs. The location of diversion tunnel or tunnels is affected by topography, abutment foundation conditions, hydraulic requirements, and economy of construction. Except for some high-head dams, it usually is economical to place an outlet tunnel near stream elevation and use it for diversion during construction. A tunnel should be located far enough into the abutment to obtain adequate cover for the character of rock encountered, and the tunnel alignment must meet the hydraulic 1541