How are gravity dams made?

How are gravity dams made?

A gravity dam built up of boxes, crossed timbers, or gabions filled with earth or rock. Roller-compacted concrete dam. A concrete gravity dam constructed by the use of a dry mix concrete transported by conventional construction equipment and compacted by rolling, usually with vibratory rollers.

How do forces act on a gravity dam?

Due to vertical component of acceleration, a vertical inertia force F = αW is developed on the dam. The direction of this force is in opposite direction to the acceleration. In other words inertia force acts downwards when acceleration is upwards, thus increasing the downward weight momentarily.

What is gravity dam explain with neat sketch?

Gravity dams are massive structure dam which is constructed of concrete or stone masonry. These dams are hold by the gravity to the ground. A gravity dam depends on its own weight for stability and is usually straight in plan although sometimes slightly curved. A gravity dam can hold a large amount of water.

What are the disadvantages of gravity dam?

The following are the disadvantages of a gravity dam:

• Their initial cost of construction is high.
• Their construction period is comparatively more.
• These require a strong and sound foundation.
• Dams once constructed, cannot be raised further.
• For the supervision of concrete dams, skilled labor is required.

Which is the highest gravity dam in the world?

The Grande-Dixence dam
The highest dam in the world The Grande-Dixence dam is the highest gravity dam in the world, at 285m.

How are gravity dams designed to hold back water?

Gravity dam. A gravity dam is a dam constructed from concrete or stone masonry and designed to hold back water by primarily using the weight of the material alone to resist the horizontal pressure of water pushing against it. Gravity dams are designed so that each section of the dam is stable, independent of any other dam section.

Are there any problems with a gravity dam?

Although gravity dams are expected to last anywhere from 50–150 years, they need to be maintained and regularly replaced. Another problem with gravity dams involves ecosystems. Because the flow and amount of water changes when a dam is built, it generally has an impact on the area of the dam and everything afterwards.

When is grouting done on a gravity dam?

Grouting at pressures up to about 40 psi may be done before concrete is placed for the dam, but high-pressure grouting (200 psi) is done from permanent galleries in the dam after the dam is complete so that the weight of the dam can resist the grouting pressures.

Why are inspection galleries important in a gravity dam?

Inspection galleries to permit access to the interior of the dam are formed as the concrete is placed. These galleries may be necessary for grouting operation, for operation and maintenance of gates and valves, and as intercepting drains for water which seeps into the gravity dam.