The soil obtained from digging into the ground is deposited between the area to be dug and the shield (generally 2 metres). It is extracted by a continuous flight auger which decompresses it, so that it can be removed from the already dug gallery.
The extracted soil is then replaced with compressed air.
A hyperbaric airlock, fitted to the shied, can be used to compress a team of hyperbaric chamber technicians. When the pressure equalises, these personnel can then enter the excavation area to inspect, change or repair the cutting wheel parts.
During this time interval, the chamber technicians are subjected to breathing compressed air. They must then exit the airlock while observing to decompression schedules.
In manufacturing a tunnel borer airlock, TECH PLUS commissions inspection bodies to check the design briefs and perform a validation of the hydraulic tests, in compliance with European directive 97/23 CE.
The hyperbaric airlocks for tunnel borers comply with the CE 12110 European standard and the EN 13445 international standard.