What are the parts
of a gravity dam? |
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abutment (*)
axis (*)
crest (*)
cross section (*)
downstream face (*)
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foundation (*)
heel (*)
height (*)
plan view (*)
reservoir (*)
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span (*)
toe (*)
upstream face (*)
width (*)
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Gravity dams use their weight to hold back the water in the reservoir.
Gravity dams can be made of earth or rock fill or concrete. In this section
we will concentrate on concrete gravity dams. These dams can be very
expensive because of how much material they use.
Generally, the base of a concrete gravity dam is equal to approximately 0.7
times the height of the dam:
base = 0.7 * height
The shape of the gravity dam resembles a triangle. This is because of the
triangular distribution of the water pressure. The deeper the water, the more
horizontal pressure it exerts on the dam. So at the surface of the reservoir,
the water is exerting no pressure and at the bottom of the reservoir, the
water is exerting maximum pressure. The shape can vary slightly; any of these
shapes can be used for a simulation of a gravity dam if the exact shape is not
known. |
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Roll over each shape of gravity dam:
plain
vertical top
slanted upstream face
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The slant on the upstream face in the third shape allows water to weigh down
on the dam, increasing its stability.
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How would you model a
gravity dam for a simulation?
You would model a cross-section of the gravity dam, like the
cross-section shown above. To the right, a model of a gravity dam with an
inspection passageway is shown.
Your model should be scaled down from the real dam; that is, the size of
you model of the dam should be a proportion of the size of the actual
dam. |
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How is the dam attached to the ground?
You'll notice that the dam is attached to the foundation in the pictures
at the top.
You'll have to tell the computer where your dam is attached to the foundation.
In the picture to the left, the model dam is attached to the ground along the bottom
of the dam -- that's what the red dots mean.
 A civil engineer calls the points where
a structure is attached to something else its fixity. |
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