When construction takes place after that it becomes visible in the water and the engineers use a series of large driven piles into the waterbed which is called Cofferdams.
Coffer means box. The piles of the cofferdams is operated deep inside the earth in any form necessary to a specific depth because if the water is on one side of the wall than the water is pumped out from the other side of the wall because it creates a hydraulicly unstable system which can cause water to drip through the ground without getting to compound into the geotechnical engineering of this hydraulic phenomenon.
There is a depth in which the wall can be handle into the ground which will keep water from dripping up into the other side of the wall. The depth defines by soil type and the surrounding water table. The piles make use of it in cofferdams for construction. Usually drove into the surface at minimum height in command to keep the water out.
The cofferdam is in a place where the pumps are employ to take the water out into the structure of the dam. This creates a workplace. Sometimes getting the pile that makes the cofferdams to unnecessary depth on ocean, lake, or river, is very expensive. In this type of situation, a series of pumps in a place to pump out the extracted water as it sips into the cofferdam structure.
Either underwater construction, the cofferdam is much safer. It is a permanent solution. As the project gets completes the water is pump back in the cofferdam and the piles get remove. Giant Cofferdams are the most impressive. In some of the regions in the world, the cofferdam is said as Caisson.
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The advantages of Cofferdams are:-
- Cofferdams allow the construction of the structures because of the poor environment.
- It provides a safe environment to work.
- Contractors typically have design responsibility.
- The steel sheet piles can easily install and can get easily remove.
- Materials can typically use again on the other projects.
The two main types normally used in the construction of dams are:-
Earthen Cofferdam
Earthen Cofferdam vividly covers the technical and social aspects of constructing earthen dams with community participation. The construction should be finished where the depth of the water is not much. Overhead the ground level right over the cut-off trench. They raise a core wall in the same way as the trench fill. The core wall constructs by puddle clay. It helps to control the sewage water of the dam.
Rock-fill Cofferdam
The rock-fill construction adopts only the stone which is easily available nearby. The stones keep together and it requires the shape of the earthwork. The voids are partial fills up with the earth and stone-chips. The water on the slide slope protects by pitching.
