Working under air pressure

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