Dam & Pressure acts on dam

DAM

Represent by Pravin patil

Definitions • A dam is a structure which prevents the

flow of water and accumulates it in a reservoir

• Dam is a solid barrier constructed at a suitable location across a river valley to store flowing water.

Types of damArch

Gravity

Buttress

Earth

Purpose

1. Drinking and domestic water supply2. Flood control3. Irrigation4. Industrial water supply5. Hydroelectric energy production6. Retention and control of sediments7. Improvement of water quality8. Fish Farming

Classification of Dams

According to Height of dam

• High Dam– If the height is more than 100m.

• Medium Dam– If the height is between 50-100m

• Low Dam– If the height is below 50

GRAVITY DAM

• Gravity dams are dams which resist the horizontal thrust of the water entirely by their own weight. They use their weight to hold back the water in the reservoir.

Section of a Gravity Dam

Bhakra Dam, Himachal Pradesh -  India's second tallest at 225.55 m

GRAVITY DAMSForces Acting on a Gravity Dam

1. Weight of the dam2. Water pressure3. Uplift pressure 4. Wave pressure5. Earth and Silt pressure6. Earthquake forces7. Ice pressure 8. Wind pressure9. Thermal loads.

WEIGHT OF THE DAM

W = W1 + W2 + W3

WATER PRESSURE

• Force due to water pressureP = W H2 / 2

• This acts at a height of h/3 from base of the dam.

WATER PRESSURE

UPLIFT PRESSURE

• Uplift pressure is the upward pressure exerted by water as it seeps through the body of the dam or its foundation.

UPLIFT PRESSURE

SILT PRESSURE

• Silt gets deposited against the upstream face of the dam.

• If h is the height of the silt deposited, then the force exerted by this silt in addition to external water pressure, can be

Psilt = γsat .h2 . Ka / 2• It acts at h/3 from base.

ICE PRESSURE

• The ice may be formed on the water surface of the reservoir in cold countries, may sometimes melt and expand.

• The magnitude of this force varies from 250 to 1500 KN/m2 depending upon the temperature variations.

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