Norwegian railways protect assets from freezing

• Published in: Tunnels & Tunnelling International no. JUL; pp. 44 - 47
• Main Author: JONES, Maurice
• Format: Journal Article Trade Publication Article
• Language: English
• Published: Sidcup Progressive Media Group 01-07-2011; Compelo
• Subjects: Airports; Applied sciences; Buildings; Buildings. Public works; Cold; Concrete; Design; Exact sciences and technology; External envelopes; Groundwater; Heat; Infrastructure; Leakproofness; Railway tracks (foundations and track subgrades); Stone; Temperature; Transportation infrastructure; Tunnels, galleries; Norway; Europe; Sprayed coatings; Project evaluation; Railway; Lifetime; Test; Railway network; Reliability; Protection; Railway tunnel; Freeze; Waterproofing
• ISSN: 1369-3999

Masterseal 245 was first trialled in a small tunnel in Norway in 2008, but the Gavingasen Tunnel is the first full-scale installation in a Nordic country. Following its application to a short section in 2009 and [Sintef] tests (see below) Jernbaneverket agreed to apply the new system to a length of approximately 185Om in the central part of the tunnel along with more conventional methods of sealed draining at either end. BASF's Karl-Gunnar Holter explains that as the main design for the tunnel had already been made, the inclusion of Masterseal together with sprayed concrete lining could be brought forward quickly, with initiation of work within six months. In order to test the actual heat transfer properties between the ground rock and tunnel interior across a sprayed concrete lining with Masterseal 345 double-bonded sprayed waterproofing membrane, Sintef has been carrying out a programme, supported by Jernbaneverket, to establish the properties of the combined layers. The balance of cold in a tunnel in winter, and the relative heat from the rock, may be crucial in maintaining the integrity of the lining and the waterproofing membrane. The concern is that groundwater in rock fissures connecting with the extrados of the lining could freeze, expand, and cause damage, but no such action has been determined, it is understood, due to the minimal heat loss preventing water freezing in the rock. So far the Sintef tests and the tunnel installation have confirmed that everything is going according to design intentions. Blocks of local Storen granite cut to uniform size and representing the ground surrounding a tunnel separate the two rooms. The blocks' size is limited by the practicality of handling when installing. Each is 1 .5m long, projecting into the 'cold' room representing the tunnel. Both rooms can have their temperatures maintained at require levels by air conditioning units and heaters. During testing the 'warm' room is kept at a constant temperature of 7-9°C to represent the ground temperature, which tends to remain stable. In the insulated 'cold' room the temperature is adjusted as required to represent the tunnel air temperature, using computer control, down to about -20°C. The computer controls the temperature in cycles to simulate natural conditions, and these cycles can be varied by the operator as required. Between the granite rock mass and the 'cold' room, layers can be installed to represent the tunnel lining. In this case the layers consist of a layer of sprayed concrete, reinforced with polypropylene fibres, to represent the tunnel primary lining, the sprayed membrane of BASF Masterseal 345 bonded to it, and finally another layer of fibre-reinforced sprayed concrete, also bonded to the membrane. The three together are 125mm thick.