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.