Czech firm Subterra has completed a stormwater project at Prague VH Airport in Ruzyně.
The project, which is designed to protect the airport from flooding, involved the construction of a 16m-long tunnel.
Subterra, which is part of the Metrostav Group, used an AVN Herrenknecht system for the first time at the rather unusual jobsite – directly inside the airport area.
The AVN1200TC machine was partly used in mixed soil conditions and encountered much stronger uniaxial compressive strength (UCS) than expected. Initially, the micro-TBM was selected and delivered with a mixed cutterhead capable of handling UCS of 25-50MPa. However, as work started, a much stronger UCS of up to 120MPa was discovered.
To solve the problem, at short notice Herrenknecht provided a rock cutterhead with an extension for a 1720mm diameter pipe from its rental department.
