Based on design we will classify dams on following basis
A gravity dam is an enormous sized dam fabricated from concrete or stone masonry. They’re designed to hold massive volumes of water. By utilizing concrete, the load of the dam is actually in a position to withstand the horizontal thrust of water pushing towards it. Because of this it’s known as a gravity dam. Gravity primarily holds the dam right down to the bottom, stopping water from toppling it over.
Examples of Gravity dam: Grand Coulee Dam (USA), ( Nagarjuna Sagar Dam (India) and Itaipu Dam ( Between Brazil and Paraguay).
An earth dam is product of earth (or soil) constructed up by compacting successive layers of earth, utilizing essentially the most impervious materials to form a core and inserting extra permeable substances on the upstream and downstream sides. A facing of crushed stone prevents erosion by wind or rain, and an ample spillway, normally of concrete, protects against catastrophic washout of water overtoping the dam.
Earth dam resists the forces exerted upon it primarily because of shear strength of the soil. Though the load of the earth dam also helps in resisting the forces, the structural behavior of an earth dam is entirely different from that of a gravity dam. The earth dams are normally built in broad valleys having flat slopes at flanks (abutments).The foundation requirements are much less stringent than those of gravity dams
Examples of earthfill dam: Rongunsky dam (Russia) and New Cornelia Dam (USA).
A rockfill dam is constructed of rock fragments and boulders of huge size. An impervious membrane is positioned on the rockfill on the upstream side to reduce the seepage by means of the dam. The membrane is often manufactured from cement concrete or asphaltic concrete. In early rockfill dams, steel and timber membrane were also used, however now they’re out of date.
A dry rubble cushion is positioned between the rockfill and the membrane for the distribution of water load and for offering a assistance to the membrane. Generally, the rockfill dams have an impervious earth core within the center to check the seepage instead of an impervious upstream membrane. The earth core is positioned against a dumped rockfill. It’s essential to supply adequate filters between the earth core and the rockfill on the upstream and downstream sides of the core in order that the soil particles will not be carried by water and piping doesn’t occur.
Examples of rockfill dam: Mica Dam (Canada) and Chicoasen Dam (Mexico)
An arch dam is curved in plan, with its convexity in the direction of the upstream side. An arch dam transfers the water stress and other forces primarily to the abutments by arch action. An arch dam is sort of appropriate for narrow canyons with sturdy flanks that are able to resist the thrust produced by the arch action.
The part of an arch dam is roughly triangular like a gravity dam however the part is relatively thinner. The arch dam may have a single curvature or double curvature within the vertical plane. Typically, the arch dams of double curvature are economical and are used in practice.
Examples of Arch dam: Hoover Dam (USA) and Idukki Dam (India)
Buttresses are triangular concrete partitions which transmit the water pressure from the deck slab to the foundation. Buttresses are compression members usually spaced throughout the dam site every 6 to 30 meter, relying upon the size and design of the dam.
Buttress dams are generally referred to as hollow dams because the buttresses don’t form a solid wall stretching throughout a river valley.The deck is often a reinforced concrete slab supported between the buttresses, which are often equally spaced.