This document discusses different types of dams used in civil engineering. It describes dams as barriers that hold back surface water and underground streams. The main types discussed are arch dams, gravity dams, arch-gravity dams, embankment dams, barrage dams, and natural lava dams. Each type is defined based on its structure, materials used, and how it resists water pressure. Reservoirs created by dams provide water for activities like irrigation and hydroelectric power generation.
2. Dam
• A dam is a barrier that stops or restricts the
flow of surface water or underground streams.
• Reservoirs created by dams not only suppress
floods but also provide water for activities
such as irrigation, human
consumption, industrial use, aquaculture,
and navigability.
• Hydropower is often used in conjunction with
dams to generate electricity.
3. • A dam can also be used to collect or store
water which can be evenly distributed between
locations.
4. Types of dams
• Dams can be formed by human agency, natural
causes, or even by the intervention of wildlife
such as beavers.
• Man-made dams are typically classified
according to their size (height), intended
purpose or structure.
5. By structure
• Based on structure and material used, dams are
classified as easily created without materials,
• arch-gravity dams,
• embankment dams or
• masonry dams, with several subtypes.
6. Arch dams
• In the arch dam, stability is obtained by a
combination of arch and gravity action.
• If the upstream face is vertical the entire
weight of the dam must be carried to the
foundation by gravity, while the distribution of
the normal hydrostatic pressure between
vertical cantilever and arch action will depend
upon the stiffness of the dam in a vertical and
horizontal direction.
7. • When the upstream face is sloped the
distribution is more complicated.
The normal component of the weight of the
arch ring may be taken by the arch action,
while the normal hydrostatic pressure will be
distributed.
• Two types of single-arch dams
• the double-curvature
8. Gravity dams
• 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 mass of the
dam.
• The water presses laterally (downstream) on
the dam, tending to overturn the dam by
rotating about its toe (a point at the bottom
downstream side of the dam).
9. • For this type of dam, it is essential to have an
impervious foundation with high bearing
strength.
• Uplift pressures are hydrostatic pressures
caused by the water pressure of the reservoir
pushing up against the bottom of the dam.
• If large enough uplift pressures are generated
there is a risk of destabilizing the concrete
gravity dam.
10. Arch-gravity dams
• A gravity dam can be combined with an arch
dam into an arch-gravity dam for areas with
massive amounts of water flow but less
material available for a pure gravity dam.
• The inward compression of the dam by the
water reduces the lateral (horizontal) force
acting on the dam.
11. barrage dam
• A barrage dam is a special kind of dam that
consists of a line of large gates that can be
opened or closed to control the amount of
water passing the dam.
• The gates are set between flanking piers which
are responsible for supporting the water load,
and are often used to control and stabilize
water flow for irrigation systems.
12. Embankment dams
• Embankment dams are made
of compacted earth, and are of two main types:
"rock-fill" and "earth-fill".
• Like concrete gravity dams, embankment dams
rely on their weight to hold back the force of
water.
13. Cofferdams
• A cofferdam is a barrier, usually temporary,
constructed to exclude water from an area that is
normally submerged.
• Made commonly of wood, concrete,
or steel sheet piling, cofferdams are used to allow
construction on the foundation of permanent
dams, bridges, and similar structures.
• When the project is completed, the cofferdam
will usually be demolished or removed unless the
area requires continuous maintenance. (See
also causeway and retaining wall.)
14. Natural dams
• Dams can also be created by natural geological
forces.
• Lava dams are formed when lava flows,
often basaltic, intercept the path of a stream or
lake outlet, resulting in the creation of a
natural impoundment.
15. • An example would be the eruptions of
the Uinkaret volcanic field about 1.8 million–
10,000 years ago, which created lava dams on
the Colorado River in northern Arizona in
the United States.
• The largest such lake grew to about 800 km
(500 mi) in length before the failure of its
dam.