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Pneumatic Caissons

For caissons, a concrete structure is built at ground level, with wedge like cutting shoes created underneath. These are approx. 2 metres high, so people can work underneath the floor of the structure after completion during sinking.

The caisson sinks by removal of the soil with water cannon and sand pumps. The soil/water mixture  this produces is removed by means of hydraulic soil transport. When the water table is reached underneath the caisson, increased air pressure is applied to be able to continue working in the dry.

Staff must enter and exit through an air lock. Caisson legislation dictates stringent safety requirements for staff. The caisson is accurately positioned at the required depth using bentonite lubrication along the walls and internal or external ballast all depending on the size and shape of the structure. Once the required depth has been reached, the work area is filled with concrete to complete the foundation of the structure.

 

A presentation of this technique (film of approx. 17 min.) on pneumatic sinking of caissons for the Lock in IJmuiden you can see  to click on the link below. 

Click here for the start of the film.

For questions and application options about this and other techniques, please contact VSF.

Application

  • This method can be used for large (and deep) cellar structures, bridge piers, entrance and exit shafts of tunnels, pumping stations, lock heads and quay wall structures.
  • Usually the caisson is placed on a soil layer that has enough bearing capacity so no extra piling is necessary.  
  • It is possible to install piles beforehand and sink the caisson onto these.

Ambient factors

  • Low vibrations and low noise.
  • Relatively small space needed at ground level.
  • No construction pit or drainage necessary.
  • A sludge depot is needed in the area for the soil/water mixture that is pumped from underneath the caisson.
  • If there is limited space, a desanding plant can be used to limit the footprint.

Pros and Cons

  • VSF is the only company in the Netherlands with extensive experience in engineering and performance of pneumatic caissons.
  • The advantage is traditional construction at ground level.
  • Hardly any influence on to adjacent structures.
  • The structure may have to be heavier and stronger for the installation phase than for the actual use.
  • Faster to produce than the traditional method of construction pits

Applicated

Name of project

Client

Caisson Binnenhoofd New sealock, IJmuiden OpenIJ EPC v.o.f.
Caisson Buitenhoofd New sealock, IJmuiden OpenIj EPC v.o.f.

Caisson Neue Bahnbrücke Kattwyk, Hamburg (Germany)

Arbeitsgemeinschaft (ARGE) Neubau Kattwyckbrücke

Amsterdam, Entrance shafts Noord-Zuid subwayline (part 1,2 and 3)

Heijmans Civiel

 

 

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