Earth-fill dams

Published on 29 January 2008

 

Earth-fill dams have primarily one advantage, in that they can be built on foundations of mediocre quality - in other words, foundations that are susceptible to compression.

All earth-fill dams may be considered as gravity dams, in other words they resist the pressure of water by their own weight. This is what explains their trapezoid shape. There are three types:
- homogeneous,
- core wall,
- membrane.

  • Homogeneous dam

An earth-fill dam is called homogeneous when it is made up of a single material, which is predominantly clay-like and relatively impermeable. Depending on the structures involved, the inclines of the banks will be more or less steep, depending mainly on the characteristics of the material used.

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301_cle091935.gif
Remblai = earth-fill; Drain = drain; Injection ou coupure étanche = injection or sealed cut
  • Core wall dam

In a core wall dam, the resistance and sealing functions are separated in some way. Resistance is ensured by shells located on the sides of the structure, and impermeability by the central core.

The central core of the structure will be made up of the most impervious earth possible. It will be held on each side by shells made up, depending on the dam in question, of more pervious earth, silt or rockfill.

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302_cle088a4b.gif
Recharge (alluvions ou enrochements) = shell (silt or rockfill); Noyau = core; Drain = drain; Injection ou coupure étanche = injection or sealed cut
  • Membrane dam

There may also be sites where no earth is available, but only rockfill. This is then employed to make the body of the dam, whereas sealing is by means of a concrete, cement or bituminous cement membrane applied to the structure itself, on the upstream side.

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303_cle0fd431.gif
Recharge (alluvions ou enrochements) = shell (silt or rockfill); Masque = membrane; Injection ou coupure étanche = injection or sealed cut