Freezing work on 13 cross-passages for the High Speed 2 (HS2) line in London
Skanska Constain and Strabag (SCS JV)
REDPATH DEILMANN is the managing partner of the joint venture RDMI Freezing Ltd JV.
London, England
2022
until 2025
Project overview
The High Speed 2 project (HS2) is a planned high-speed rail line in the United Kingdom. The new line will initially connect the cities of London and Birmingham and will be extended to Manchester and Leeds in further construction phases. The aim of the project is to reduce travel times and improve the rail infrastructure in the long term.
RDMI Freezing JV Ltd, a joint venture between REDPATH DEILMANN GmbH and DMI Injektionstechnik GmbH, was responsible for the freezing of a total of 13 cross-passages in the Northolt Tunnel West section in London as part of the route construction between London and Birmingham.
Freezing technology and process
A supply and return system is installed for cross-flow freezing. This allows the refrigerant CaCl2 to circulate through freezing pipes previously arranged in the floor around the cross-cut. Four freezing pipes are connected in groups and the supply and return pipes are connected to the freezing system. The system cools the refrigerant down to -33°C to form a frost body in the floor in the cross-passage area.
A comprehensive monitoring system supervises the freezing process. As soon as the specified parameters are reached, the excavation work for the crosscut is released. The frost body is maintained during the excavation.
Once the concreting of the inner shell of the cross-passage has been completed, the freezing system is switched off and the coolant is pumped out of the supply and return system. All components are then prepared for their next use.
