A pneumatic caisson is a watertight structure used for construction in water and wet areas. These caissons are square-shaped and designed to keep water out of the construction zone by acting as a barrier from the wet environment, keeping the inside of the structure dry. They are utilized for many marine projects such as bridges and dams.
How is a Pneumatic Caisson Constructed
The pneumatic caisson structure comprises a reinforced concrete caisson with a working chamber inside at the lower part. Pressurized air is flowing into the chamber to prevent water from getting inside. Finally, the whole caisson structure is sunk into place to begin working. Pneumatic caissons are usually closed at the top but open at the bottom. This is what makes them distinguishable from regular caissons.
How Does a Pneumatic Caisson Work
The pneumatic caisson works like a cup holding air inside and pressed into water upside down. Since no air escapes from the cup, water cannot enter, as air pressure keeps it out. The pneumatic caissons have an airtight chamber at the bottom, which compressed air is pumped in to prevent water from entering. Inside the chamber, soil is excavated just like for normal land construction work.