Caisson

Caisson: In engineering, a box-like structure used underwater or as a foundation for construction work. It is usually rectangular or circular in plan and is probably tens of meters in diameter.

A box cassion, open at the top and at the bottom, is usually built on the ground, then launched, brought into position, and sunk to an already prepared foundation, with its upper edge above water level Is omitted. It serves as a shell suitable for a pier, seawall, breakwater, jetty or similar work, remaining permanently at sea level.

An open case, open at both the bottom and top, is fitted with a cutting bottom edge, which allows sinking through soft material, while excavation is carried out through the hive of large pipes, or dredging wells. As the excavation proceeds and kison sinks, additional sections are added to the shaft above. This process is continued until the caisson has sunk to the required depth. A floor, usually of concrete, is placed to provide a bottom seal. The dredging wells can then be filled with concrete to complete the structure.

Pneumatic caissons are similar to open caissons except that they are provided with airtight bulkheads above the cutting edge. The space between the bulkhead and the cutting edge, called the Working Chamber, is pressurized to the extent necessary to control the flow of soil and water; Thus excavation can be done by workers working in the working chamber at the bottom of the chamber.

Casson Foundation

Seasons represent waterway structures that are built in connection with the excavation of foundations in bridges, piers, river and lake dock structures, future conservation, and more. The kison remains in its posture and thus becomes an integral part of the permanent structure. It can be made of wood, steel or reinforced concrete etc.

When caisson is required

The following conditions are appropriate for the following Foundation:

• When there are large boulders in the soil, which impedes the penetration of the pile.
• When a large sub-construction is required to extend above or below the rear bed to provide resistance against destructive forces caused by floating objects and scores, etc.
• When the foundation is subjected to a large lateral load.
• When the water level in river and sea is high.
• When there are river forces involved in load compositions.
• When the load needs to be carried at the end, the caisson is preferred.
• Caissons are suitable when current groundwater levels are aggressive flows.

Types of Caisson

There are many types of Caisson foundations: 

• Box Caissons
• Excavated Caissons
• Floating Caissons
• Open Caissons
• Pneumatic Caissons
• Compressed Air Caissons
• Monolithic Caissons

Box caissons

Box cases have boxes with four arms and a floor. The top of these boxes is open. The concrete box is built on the ground. The prepared box caisson is placed at the foundation location and placed at pre-prepared bases. Once placed in the appropriate location, the entire void space is filled with concrete in such a way that it becomes an integrated part of the already prepared base.

Box ghats are used to construct bridge ghats.

Box caissons are less expensive. When it is not possible to construct site types requiring caissons or economy types, the box serves the caisson objective.

Excavated Caissons

These types of casings are used for digging. Cylindrical in shape, these caissons are filled with concrete.

Floating Caissons

These are prefabricated boxes filled with concrete. It is also called floating dock.

Open Caissons

Open caissons are very much like box caissons. There are two types of open casein. Both top and bottom open and open top closed bottom. Soft soil is suitable for this type of caisson. Open caissons are used in the construction of ferries, deep manholes, pump stations, micro-tunneling, etc.

Pneumatic caissons

Watertight or box caissons that are used in underwater construction are known as pneumatic caissons.

Compressed Air Caissons

This type of chisel is suitable for padded working conditions where other methods may seem inconvenient.

Monolithic Caissons

Large size of Caissons compared to others.

Construction Process

The following steps can be followed to create a caisson:

• We should first determine the place for the establishment of caisson.
• The caisson then has its first 3.7 m east cast.
• After this, with the help of a towel, the caisson is taken in its place and tied in the caisson guide.
• After that, concrete is poured using slip forming and as the concrete goes, the box becomes heavy and is submerged in water with casein guides.
• Mooring cables are used to hold caissons in place.
• When the caisson finally touches the bottom of the river, the mooring cables are removed.
• Finally, the cap is inserted.