In the caisson construction process, a caisson is a wasterlight structure that uses an anchor for foundation. It usually carries the building loads at the lower ends which are shaped as a bell. Caissons are generally constructed of concrete, steel, or wood. As with any construction project, the material to be used will depend on the function of the caisson and the type of caisson being constructed.
Caisson construction services include a whole procedure of pre construction, during construction and post construction. On completion of the caisson system there is a provision of engineered drawings to make the process appear wholesome.
Considering all the processes of construction, a caisson is said to be a critical component since it provides stability. Where the ground can, and will, shift under the weight of a new structure, a caisson can be used to distribute its load evenly.
The Caisson Construction Process
Following are the step to be followed to build a caisson:
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- After some initial formwork and concrete pours, the cutting edge is floated to the breakwater by towboat and fastened to the caisson guide. Concrete is placed into steel forms built up along the perimeter of the box. With every concrete placement, the box becomes heavier and sinks into the water along the caisson guide.
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- Forms are also built inside the box around the air domes and concrete is placed in between. The resulting open tubes above the air domes are called dredge wells.
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- When the caisson finally touches the river bottom, the air domes are removed and earth is excavated through the long dredge well tubes, as shown in the animation below. The caisson sinks into the river bottom. Excavation continues until the caisson sinks to its predetermined depth.
- As a final step, concrete is placed into the bottom of the hollow dredge wells and the tops are sealed.
Conditions Requiring Caisson Construction
Below mentioned are some of the common instances for caisson construction:
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- When the soil contains large boulders, which obstruct penetration of piles
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- A massive substructure is required to extend to or below the rear bed to provide
resistance against destructive forces due to floating objects and score etc
- A massive substructure is required to extend to or below the rear bed to provide
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- The foundation is subjected to a large lateral load
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- Depth of water level in the river and sea is high
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- There are river forces included in the load compositions
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- When the load is needed to carry at the end, caissons are preferred
- The present groundwater level is aggressive inflow, caissons are suitable
Essential Requirements for Caisson Construction
There are a number of requirements for caisson construction that exist for the purpose of sinking, filling and sealing. The most crucial factors include the height of the concrete lifts and length of the reinforcement bars that need to be decided upon in consultation with the construction contractors.
To ensure the maximum assistance of operations, the on-site supervisory staff must maintain the highest standards regarding the quality of materials used in the process. More so, they must be specially trained to handle the challenging situations faced by the personnel during the sinking process of the caisson construction. This will not only make the construction process faster but also ensure safety of the workforce at all times. As it is the case with anything in construction, caisson construction needs to be done with great precision and accuracy for successful results.