Concrete Dams
Concrete dams come in a variety of types and rely on the weight of concrete and/or their shape to hold back the water. Concrete is a relatively expensive material and the construction of concrete dams is usually more labour-intensive than the construction of embankment dams.
Concrete Gravity Dams
These hold the water back because of their own weight. A number of the dams built to contain relatively small storages are of this type. Examples include Henty, Liapootah, Pine Tier and Trevallyn.
Concrete is an expensive material and different techniques have been used to reduce the quantity required.
- The Catagunya Dam was designed using high-tension steel cables anchored deep in bedrock. Eight per cent more concrete would have been needed if these cables were not used.
- TheMeadow Bank Dam is a buttress dam. It uses less concrete than a normal gravity dam and the weight of the concrete is transferred to bedrock through the downstream legs (or buttresses) of the structure
Roller-compacted concrete gravity dams involve a new construction technique designed to reduce material and labour costs. A fairly dry concrete mix is put into place and compacted using similar methods to those employed in the construction of embankment dams. The Rivers and Water Supply Commission's Craigbourne Dam is of this type and was built to supply irrigation water to the Coal River area.
 Concrete Gravity Dam |
 Liapootah Dam situated on the Derwent River |
 Buttress Dam |
 Downstream buttresses of Meadowbank dam |
Concrete Arch Dams
These rely on their shape to withstand the pressure of the water built up behind them. The arch curves back upstream and the force exerted by the water is transferred through the dam into the vally walls and floor. They are normally constructed in deep gorges and the geological foundations need to be particularly sound. The spectacular Gordon Dam (140 metres high) and Devils Gate Dam (84 metres high) are two examples.
Because the strength of arch dams relates to their shape they require only about 10 percent of the concrete of an equivalent gravity dam.
Some concrete dams use an arch shape in combination with other methods to obtain their strength.
- The large Clark Dam at Butlers Gorge is a gravity-arch dam. It relies on both its shape and the weight of concrete used.
- The second Miena Dam (completed in 1922) is a multiple-arch structure. It consists of a row of 27 concrete arches supported by concrete uprights (buttresses). The design was chosen because of its relatively low concrete content and the width of the area to be dammed.
 Concrete Arch Dam |
 Gordon Dam |
 Multiple Arch Dam |
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