Forces ating on Dam

Forces acting on the Dam:-

• Water pressure.
  Uplift pressure
  Self weight of the dam
  Earthquake pressure
  Ice pressure
  Silt pressure
  Wind pressure
  Wave pressure

  1.Water pressure:-

         It is the pressure on u/s face of the dam.The total pressure is in horizontal direction.The total pressure is given by
            P=wh.square/2
  It is the largest external force causing instability to the dam

  2.Uplift pressure:-

        When the is stored on the u/d side of the dam water seeps through body of the dam or its foundation and causes upward pressure,this upward pressure is called Uplift pressure

  3. Self weight of the dam:-

       Self weight of the dam is the only largest force which stabilizes the structure 
       the total weight of the dam acts at the C.G. of the section

  4.Earth quake pressure:-

       Earth quake causes waves in the earth crest the wave causes acceleration to the foundations under the dam this leads stress in the dam and dam may fail.Hence  dam should not be constructed in places which are subjected to earth quakes

  5.Ice pressure:-

       The ice pressure is important for dams which are constructed in cold countries 
       The ice formed on water surface of the reservoir is subjected to expansion and contraction due to variation in temperature

  6.Silt pressure:-

  the u/s river brings silt along with it and so silt get deposited . Therefore dam is subjected to silt pressure in addition to water pressure.So silt pressure should also be consider 

  7.Wind pressure:-

  Wind pressure is required to consider only on the portion of super structure which is exposed to winds normally it is taken as 1000 to 1500 N/sq.mm

  8.Wave pressure:-

  The upper portion of the dam is subjected to waves by wind
                 The pressure depends on extend of water surface