Explain Arch Dam and Buttress Dam?

Arch Dam ;

Arch dam can be defined as a solid wall, curved in plan, standing across the entire width of the river valley in a single span. The body of arch dam is generally made of cement concrete. Thus, arch dam is just a curved beam, the ends of which are restrained and the way in which the loads are resisted is termed a arch action.

Buttress Dam ;

A buttress dam or hollow dam with a solid, water-tight upstream side that is supported at intervals on the downstream side by a series of buttresses or supports. A buttress dam envisages to reduce the total volume of concrete by constricting the material where the stresses are higher and other undesirable features of gravity dam but has higher cement content per cubic metre of concrete than a gravity dam.

Arch dam

Load of reservoir water is transferred to soil by trust action and vertical action. Arch dam is mostly use in following conditions

• Abutment is strong.
• Water depth of reservoir is High.
• Valley between two mountain.
• Bottom soil have low SBC.

Buttress dam

Reservoir water load is transferred to soil by vertically and buttress wall of the dam. Buttress dam is mostly use in following condition

• Dam height is very high.
• Where dam width is very high.
• Abutment are weak.

arch dam is constructed when dam abutment has rocky strata and have higher bearing capacity to resist trust from arching action of an arch dam.

see arch dam in figure

it is constructed when river run between two hills and the dam site has great depth, and less width at that location arch dam is very economical to another type of dam.

buttress dam is a dam in which has straight alignment and which have buttressed support on the downstream side.

buttress is provided to additional support of dam structure .

the main purpose of the buttress is to provide additional safety against the overturning of the dam. this type of dam is constructed at where dam height is high.