How are bridge columns built underwater?

Braced Cofferdams:
It is a single wall of sheet piles that is put in to the excavated site on the ground. This is used for relatively shallow waters which are about 12 meters deep.

Columns

Braced Cofferdam

Cellular cofferdam:
They are used where the site does not allow the use of cross braces.In this case, the cofferdam is stable due to the forces acting on it.

Double walled sheet piled cofferdam:
They have two parallel rows of sheet piles driven to site ground and attached to each other with tie rods. The gap is then filled with a material like sand or gravel to get the work done.

Also Read: What is horizontal drilling and how does it work?

Case Drilling:
Here the water is not driven out. In this case, the chamber is watertight and uses air pressure to keep the water away. Then a sealed tube chamber is fitted into the water.A special drill is then used to make a hole on the site. Wherever water fills up the air pressure is used to remove it.

Then the drilled hole is filled with concrete and left to set. The pillars or piers for the bridge have then constructed atop these columns. Earlier lots of human labor was employed to do this work. Now in modern engineering, the same work is done by using sophisticated machines and equipment.

So here is the basic mechanism used to construct columns underwater. Hope this article has enhanced our reader’s knowledge by some percentage.

 

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