Effect or filter on seepage line.

Design of Earthen Dam


If an earth dam has to be safe and stable during construction and in its subsequent operation, it must be designed considering following points.

  • The earth dam should never be allowed to be over topped during heavy flood.
  • This object can be achieved by providing spillways of adequate capacity.

Effect or filter on seepage line.

  • Sufficient free board should be provided.
  • Seepage line should remains buried sufficiently on the D/S face when reservoir is full.
  • This will prevent occurrence of sloughing of the D/S face.
  • The dam portion laying D/S of the impervious core should be properly drained.
  • The U/S and D/S slopes should be such that they are not damaged by pore pressure during and immediately after construction.
  • The U/S face of the dam should remain stable during rapid draw downs.
  • U/S face should be protected against wave erosion and D/S face against the erosion due to heavy down pours and strong winds.
  • For this rip rap, revetment or pitching is down on U/S face and counter booms and turfs are developed on D/S face.
  • U/S and D/S slopes of the dam should be flat.
  • This will ensure safety of the dam against shear failure of the foundation.
  • In order to prevent internal erosion of the soil the seepage flow through the dam and foundation should be suitably controlled.
  • Free passage of water, wither through holes made by burrowing animals or by piping should be allowed.
  • In areas, frequently subjected to earth quakes, the dam should be designed considering earthquake resistant measures.

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