Cissons In The Construction Industry

Abstract:

This report focuses on the use of the caissons in the Construction Industry. Starting with a brief introduction about the Caissons that can be used as a foundation like piles or piers. Caissons also are preferably used when the site working conditions is not common like the case of underground structure. Then the report introduces the three different types of caissons which are the open caissons, Box Caissons and the Pneumatic Caissons. The open Caissons is subdivided into three other kinds the single wall open caissons, cylindrical open caissons and Open Caisson with dredging wells. The Construction method, advantages, disadvantages, materials, equipment and labor are discussed for each type of caissons. Consequently a comparison

Open Caissons

I. Single Wall Open Caissons

• Dewatering to dry the site

• Excavating a 3 to 4 meter deep pit with a appropriate size

• At the bottom of this pit, the cutting edge will be replaced

• Then the reinforcement of the wall and the shuttering for the formwork will take place

• Concreting will be take place at this stage

• After giving the poured concrete a suitable time to harden and gain its strength, sinking will start

• The sinking of the caissons is mainly depending on its own weight, however if the caisson own weight is not enough to overcome, additional weight can be added and to be removed after the end of the sinking process.

• Then an additional section will be added and concreted, however the sinking process will stop while concreting to be resumed after the new concreted section has gained its strength

• By reaching the required depth, the base of the caisson will be plugged by a concrete layer

• Finally after hardening the Concrete layer, all the water in the accessions will be pumped outside and replaced by sand. concrete or gravel

II. Cylindrical Open Caissons

• It is a Masonry, steel, timber and reinforced concrete cylinder with a cutting edge at the

Disadvantages

• Not effective with boulders and logs.

• The quality of the lower Concrete seal which is poured at water is not adequate.

Equipment

• Clamshell excavator.

• Mobile cranes

• Concrete pump

Labor

• Semi-Skilled Labor Open Caisson Work Space 1 http://en.wikipedia.org/wiki/Caisson_(engineering) 2. Box Caissons

• It has the same idea like the open caisson with the exception of it has a base

• The caisson sunk by its own weight and the weight of the concrete, sand or gravel that will be used to fill the spaces inside the caisson

• It is important to level the soil on which the base of the caisson will be laid.

Advantages:

• Relatively low cost.

Disadvantages:

• Needs strong bearing layer of soil to support the bottom of the caisson.

Equipment

• It could need special type of formwork to pour the concrete segments.

• Crane

Labor

Semi-Skilled Labor

Box Caisson 1

3. Pneumatic Caissons

• This type of caissons is the reverse of the box method where it’s closed at the top and open at the bottom.

• Compressed air is used to reject water from the caisson chamber.

• Caisson’s chamber or the working chamber is used by the workers to carry out the