Irrigation (61-80)

Updated: Apr 9, 2020

61. Horizontal acceleration due to earthquake results in

hydrodynamic pressure ,inertia force into the body of the dam

 

62. Hydrodynamic pressure due to earthquake acts at a height of

4H/3π above the base

 

63. The major resisting force in a gravity dam is self-weight of dam


 

64. Total force due to wave action on a gravity dam acts at a height of





 

65. When the reservoir is full, the maximum compressive force in a gravity dam is

produced at the toe

 

66. The maximum permissible eccentricity for no tension at the base of a gravity dam is B/6

 

67. Presence of tail water in a gravity dam

decreases the principal stress,decreases the shear stress

 

68.Neglecting the effect due to earthquake forces and tail water pressure, the

principal stress in a gravity dam is given by




 

69.The elementary profile of a dam is a right angled triangle

 

70.In the empty condition of reservoir and with the elementary profile of a dam, the vertical stress at heel and toe respectively / are given by 2W/B and 0

 

71.Neglecting uplift pressure, the base width of an elementary profile of a gravity dam shall be taken as





 

72.The maximum possible height of a safe dam having an elementary profile is

f/W(G+1)

 

73. The focus of base parabola for a dam having a horizontal drainage filter is at a

distance of b from toe

 

74. By providing a top width for roadway and freeboard in the elementary profile of a gravity dam, the resultant force for full reservoir condition will

shift towards the heel

 

75. For wave action in dams, the maximum height of freeboard is generally taken to be equal to





 

76. As compared to gravity dams, earthen dams require less skilled labour


 

77. The most suitable materiarfor the central impervious core of a zoned embankment type dam is clay mixed with fine sand

 

78. Seepage through embankments in an earthen dam is controlled by

drain trenches

 

79. Seepage through foundation in an earthen dam is controlled by providing

impervious cut off

 

80. The flow of water after spilling over the weir crest in chute spillway and side

channel spillway respectively are at right angle and parallel to weir crest

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