PRESENTATIONTOPIC:

DAMSPRESENTED TO:

SIR DAWOOD-UL-HASSANPRESENTED BY:

ABDUL MUTAKABERBSCT01133006

Dams Definition:

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

Storage of water is utilized for following objectives:

• Hydropower• Irrigation• Water for domestic consumption• Drought and flood control• For navigational facilities• Other additional utilization is

to develop fisheries

TYPES OF DAMS1. GRAVITY DAMS:• These dams are heavy and massive wall-like structures of

concrete in which the whole weight acts vertically downwards.

• Bhakra Dam is the highest Concrete Gravity dam in Asia and Second Highest in the world.

• In a gravity dam, the force that holds the dam in place against the push from the water is Earth’s gravity pulling down on the weight of the dam itself.

• In a gravity dam, stability is secured by making it of such a size and shape that it will resist overturning, sliding and crushing at the toe.

TYPES OF DAMS2. ARCH DAMS:• An arch dam is a type of dam that is curved and commonly

built with concrete.• The arch dam is a structure that is designed to curve

upstream so that the force of the water against it, known as hydrostatic pressure.

• An arch dam is most suitable for narrow gorges or canyons with steep walls of stable rock to support the structure and stresses.

TYPES OF DAMS3. EARTH DAMS:• An embankment dam is a massive artificial water barrier. They

are mainly built with clay, sand and gravel, hence they are also known as Earth fill dam or Rock fill dam.

• They are trapezoidal in shape.• Earth dams are constructed where the foundation or the

underlying material or rocks are weak to support the masonry dam or where the suitable competent rocks are at greater depth.

• Earthen dams are relatively smaller in height and broad at the base.

DISADVANTAGE: • Water can easily pass through it.• less durable than other type dams.• The height of this dam is less.

SELECTION OF SITES1. Topographically:• Place must be suitable.• Narrow gorge or small valley with enough catchment areas. 2. Technically:• Should be strong, impermeable, and stable.• Strong rocks leads to better designs.• impermeable sites ensures better storage • Stability with reference seismic shocks and slope failures

around the dam are a great relief to the public as well as the engineering.

3. Constructionally: • Should be not far off from deposits of materials which would

be useful for construction• Natural materials of construction Like earth, sand, gravel,

and rock should be easily feasible otherwise cost will increase.

SELECTION OF SITES4. Economically: • Benefits arising should be realistic and justified in terms

of land irrigated or power generated or floods averted or water stored.

5. Environmentally: • The site of the dam should not involve ecological disorder

(in the life of plants, animals and man).• The fishes in the streams are also affected, so things should

also be considered.• The dam and the associated reservoir should become an

acceptable element of the ecological set up of the area.

FORCES ACTING ON A DAM1. Weight Of The Dam:• In gravity dams and embankment dam the weight of the dam is the

major force acting for holding the water back on the upstream side.• The forces arising due to the weight of the dam are compressive in

nature.

2. Water Pressure:• The dam is required to resist horizontal forces acting due to weight

of the water impounded on it.• This water pressure can be calculated by hydrostatic pressure

distribution.

3. Earthquake Forces:• The disturbance in dams is highly dangerous because they store

huge volumes of water.• Dams built in the areas known to be seismically active must be

designed to withstand additional forces that are likely to arise in a future shock.

FORCES ACTING ON A DAM4. Uplift Pressure :• It is almost impossible to make a dam impervious structure.• Many minute cracks and pores are left in the dam and the

foundation body.• Water is likely to find its way into these minute openings

through seepage and gradually fill them up.• It exerts an upward pressure on the body of the dam.

MAIN CAUSES OF DAM FAILURE Common causes of dam failure include:• Sub-standard construction materials/techniques.• Spillway design error.• Geological instability caused by changes to water levels

during filling or poor surveying.• Sliding of a mountain into the reservoir.• Poor maintenance, especially of outlet pipes.• Extreme inflow.• Human, computer or design error.• Internal erosion, especially in earthen dams.

MAIN CAUSES OF DAM FAILURE

CONCLUSION Generally there are mainly the three types of dam which

are selected on the basis of need of water requirement and our basic need such as :-

• Hydropower• Irrigation• Water for domestic consumption• Drought and flood control• For navigational facilities• Other additional utilization is to develop fisheries• Due to some of the carelessness while the construction it

hampers the life and strength so it is necessary to study the basic concept of the dams.

• Utilization of dam water also promotes the production of the hydroelectricity.