Deep gates of a new design for closure of diversion tunnels: Fid-Bau Portal

Deep gates of a new design for closure of diversion tunnels

Khlopenkov, P. R.

Conclusions The discussed gate has a number of merits: the absence of deformation of the stream (except for deformation with a partial opening) ensures resistance to cavitation and vibration and increases the discharge coefficient; the action of the gate material only in compression or in tension makes it possible to reduce its weight substantially; the operation of the gate as a closed system which does not transfer its external loads to the foundation makes it possible to reduce the load on the gate 100–200 fold and to maneuver it with smaller mechanisms. The sharp reduction in load on the supporting bearings not only reduces their cost but above all, increases their dependability.The indicated properties make it possible, depending on specific conditions, to build both the principal and the emergency-repair gates in three variants: concrete, thin-wall reinforced concrete, and metal.The most dependable and economical emergency-repair gate for tunnels of large cross sections under high heads must be considered the one in the form of a concrete roll-away prism which subsequently becomes part of the concrete plug of the construction conduit; this makes it possible to allocate a considerable part of its cost to that of filling the tunnel. The high safety factor accounts for a number of advantages of this gate over other known types of emergency-repair gates.The metal, transverse multi-pipe gate used as the principal gate has definite advantages; it is highly flexible and uses a small amount of metal.The fact that the shape and dimensions of the conduit in the flow part of the gate chamber are not changed makes it possible to reduce sharply the expenditure of metal in lining and simultaneously to increase the operational dependability, thus achieving a marked savings.