Some useful techniques to construct bridge columns underwater

In this exclusive construction article, you will learn the process for erecting the columns or pillars underwater by setting up their exact positions.

Based on the construction over waters, different types of techniques like type of sand underwater, type of water, weather conditions of the area and depth of water are mostly applied.

In case of shallow waters, the piers (a type of pillar) are constructed on the temporary foundation to support the structure located above.

In case of deep water level where the conditions of soil are not supportive, several techniques are employed to uplift the piers.

Here, lies the importance of cofferdam technique. In technical term, cofferdam stands for a structure that holds water and soil in a specific area.

Depth of water is not a concern for constructing cofferdam. Now in a cofferdam, an underwater bounded room type structure is built up and it is attached with soil and water.

After that the water and surplus soil are discharged through a pump so that the area becomes dry. It needs constant pumping out of the water and other unwanted materials.

Cofferdam walls are usually formed with sheet piles supported by wailers, internal braces, and cross braces. Cofferdams stand for temporary structures and are detached once the piers are erected to support the bridge. Because of their temporary nature, cofferdams construction materials are found in template form.

The following three types of cofferdams are found :-

Braced Cofferdams: It belongs to a single wall of sheet piles that is provided to the excavated site on the ground. It is applicable for comparatively shallow waters with approx 12 meters depth.

Cellular cofferdam: They are suitable when it is not possible to utilize the cross braces. Under this situation, the cofferdam is stable as a result of the forces operate on it.

Double walled sheet piled cofferdam: They contain two parallel rows of sheet piles pushed to site ground and connected to each other through tie rods. The space is then filled with a material like sand or gravel for the completion of the work.