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Working under air pressure

When working under pneumatic pressure, it is possible to create a dry closed off workarea below the water. The waterlevel is temporarily lowered using a compressed air system. Depending on the scale of the project and the available space, (electrical) machines may be used. Materials and staff access and leave the workspace through separate air locks. This technology allows underground excavation and pouring of concrete floors. After the floor has hardened, the overpressure can be removed and finishing work performed.

Application

This technology is for instance used a wall-roof method, in which the construction pit walls and roof are built first and subsequent work takes place below ground level under air pressure to prevent water ingress. In certain situations, a floor is constructed first in the dry below ground level, with further work carried out below that floor under air pressure. For deep underground car parks, this method enables both top-down and bottom-up work from ground level.

This technology was used on a large scale for the Tramtunnel in The Hague, where traditional construction was not possible due to the problems created by incoming groundwater. This technology is also used for the deeper subwaystations (up to 30 metres below ground level!) of the Noord-Zuidlijn in Amsterdam. 

Ambient factors

  • Low vibrations and low noise.
  • No drainage needed.
  • The space at ground level can be used again once the walls and roof have been finished.
  • Space needed for systems and locks.

Pros and Cons

  • VSF has extensive experience with engineering and performance of work under air pressure.
  • The advantage is that working underneath a finished floor offers the option of building from the bottom up.
  • Hardly any influence on adjacent structures, no drainage needed.
  • A disadvantage is that the forces on the structure may be higher during the construction phase than during usage because, the structure may be heavier or temporarily ballasted to prevent cracking and uplift.

Applicated

Name of project

Client

Amsterdam, Air pressure Vijzelgracht Noord-Zuid subwayline

Max Bögl Nederland

Amsterdam, Air pressure Ceintuurbaan Noord-Zuid subwayline

Max Bögl Nederland

Zeebrugge, Air pressure renovation Visartsluis

s.a. Benelux Diving Corporation

 

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