Additional storage of water above the spillway crest can be obtained by the installation of temporary or movable gates. There are several types of gates.
The usual flashboard gates consist of wooden panels, supported by vertical pins placed on the crest of the spillway. Such installations are temporary. They are removed Text B Gates and Outlet Works when the water surface reaches in the reservoir a predetermined level.
Stop logs consist of horizontal timbers spanning the space between piers. The logs may be raised by хэнд or with a hoist. There is usually much leakage between the logs and considerable time may be required for removing Text B Gates and Outlet Works the logs if they become jammed in the slots. Stop logs are ordinarily used for small installations.
Needles consist of timbers with their lower ends resting in a keyway on the spillway crest and their upper ends supported by a bridge. Needles are somewhat easier to remove than stop logs Text B Gates and Outlet Works but are quite difficult to place in flowing water. Consequently they are used mainly for emergency bulkheads where they need not be replaced until flow has stopped. There are some other types of gates, such as vertical lift gates, radial gates, rolling gates, bear-trap gates Text B Gates and Outlet Works, drum gates.
Outlet works must be provided in order that water can be drawn from the reservoir when it is required. This water may be discharged into the channel below the dam or may be transported in pipes or canals to some distant point. All outlet works must be provided with Text B Gates and Outlet Works gates or valves in order to regulate discharges of water.
A sluiceway is a pipe or tunnel that passes directly through a dam or the hillside at one end of the dam and discharges into the stream below. The outlets of most dams consist of one or more sluiceways, with Text B Gates and Outlet Works their inlet being at about minimum reservoir level. If the quantity of discharged water is to vary considerably, then several sluiceways are required.
Sluiceways may be circular or rectangular. The interior should be smooth and without projections or cavities. Considerable attention should be given to the design Text B Gates and Outlet Works of the sluiceway entrance. A bell mouth entrance is generally used.
Answer the following questions.
1) What are gates used for?
2) What types of gates are there?
3) What do the flashboard gates consist of?
4) When are the flashboard gates removed?
5) What do stop logs consist of?
6) What are stop logs Text B Gates and Outlet Works used for?
7) What do needles consist of?
8) Are needles quite difficult to place in flowing water?
9) Where are needles used for?
10) Why must outlet works be provided?
11) Why must all outlet works be provided with gates or valves?
12) What is a sluiceway?
13) What do the outlets of most dams Text B Gates and Outlet Works consist of?
14) When are several sluiceways required?
15) May sluiceways be polygonal in shape?
16) What should the interior of sluiceways be?
17) What is also important for sluiceways?
Finish the following sentences according to the text.
1) The spillway crest can be obtained ... .
2) The flashboard gates consist of ... .
3) The Text B Gates and Outlet Works logs may be ... .
4) Stop logs are ordinarily used for ... .
5) There are some other types of gates, such as ... .
6) The water may be discharged into ... .
7) Considerable attention should be given to ... .
Fill in the sentences with the words from the list below.
|emergency bulkheads Text B Gates and Outlet Works||circular||temporary|
1) Additional storage of ... above the ... crest can be obtained by the installation of ... or movable gates.
2) The logs may be raised by хэнд or with ... .
3) Flashboard gates are removed when water surface reaches a ... level.
4) ... consist of timber with their lower ends resting Text B Gates and Outlet Works in a keyway on the spillway crest and their upper ends supported by a bridge.
5) Needles are used mainly for ... where they need not be replaced until flow has stopped.
6) The water may be discharged into the ... below the dam or may be transported in ... or canals to Text B Gates and Outlet Works some distant point.
7) The outlets consist of one or more ... .
8) Sluiceways may be ... or ... in shape.
Using the dictionary add as many words as possible into the table.