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混凝土水坝
There are two ways to look at categorising concrete dams -
- by construction method:
- or by design principles:
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Cast
In this technique,the concrete is mixed on-site in a concrete batching
plant, then poured into moulds. When the concrete has set, the next section
can be poured on top, allowing the dam to be built up from many sections,
each about 2m high.
Roller-Compacted Concrete (RCC)
This uses a drier, firmer concrete mix than the above method. Concrete
walls are first built in situ, on both the upstream and downstream
sides of the dam, then the concrete is poured in between them, and spread
in thin layers to a depth of about 600mm (see
photograph). The concrete is then compacted by large, heavy,
vibratory rollers. The RCC method is usually more economical and faster
to build than more traditional techniques, and the smaller volume of ground
needing to be excavated to provide the raw material makes them environmentally
more acceptable.
拱坝
These are usually, though not exclusively, constructed by the cast concrete
method. They are, not surprisingly, arch-shaped, with the bow of the arch
pointing upstream (see
photograph). They require a narrow, steep-sided valley with strong
base and sides. This design uses the innate strength of the arch shape,
with the force from the water being directed to the rock abutments at
the ends of the arch. Due to the strength of the arch, dams of this kind
are often surprisingly thin, compared with other designs, often being
no more than 2 - 4m thick at their thickest point.
混凝土拱坝应用示例
重力坝
The term "gravity dam" can actually refer to either a concrete
dam or a masonry dam, but the principle is the same in either case. A
gravity dam has a cross-section roughly that of a right-angled triangle,
where the hypotenuse is the downstream face (see
diagram). The dam is held in place by gravity, and its weight
and shape combine to keep the weight of water behind it from pushing it
over. It is suitable for all kinds of valley, but must have a foundation
of very strong, stable bedrock.
A variation on the standard Gravity Dam is the Buttress Dam.
This is similar to a gravity dam, but the downstream side is supported
by several triangular walls, or buttresses.
混凝土坝监测示例
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