With the growing world population and the rising transport volume, smart underground tunnel solutions become a necessity. Safety is a major aspect in tunnel construction and operation. In order to ensure safe escape routes in case of emergency, cross passage construction is gaining importance for twin tunnel concepts and escape shaft solutions. Especially in water-bearing ground with high groundwater pressures or in non-stable soil conditions, cross passage construction requires mechanized concepts.
Shaft to Tunnel
When emergency exits must be connected to existing traffic tunnels, the construction of a shaft and connection to the tunnel may require a mechanized cross passage concept. In this case, a tunnel boring machine is pushed from the shaft towards the tunnel, excavating the ground and installing the final lining during advance. The machine is then dismantled after breakthrough in the tunnel.
Shaft towards Tunnel – Blind hole
In some cases, the construction of the cross passage has to be carried out without impact on the target tunnel. The use of a retractable machine concept allows excavation of the cross passage until a predetermined end position close to the tunnel and the retraction of the tunneling machine back to the launch shaft. Final connection of the cross passage to the tunnel can be made at a later stage, e.g. by means of a grout block.
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