Engineering application and study on polyurethane-corrugated steel plate insulation lining of existing railway tunnel in seasonal frozen area

In order to solve the problem of freezing damage treatment and anti-freezing design for railway tunnels in operation in the seasonal frozen area, this paper proposes a polyurethane-corrugated steel plate insulation lining, and studies its thermal insulation effect, relying on a freezing damage treatment project of an existing passenger-dedicated tunnel for on-site application. In this paper, the insulation lining is applied to the actual project and the insulation effect is verified by the field monitoring. The temperature test section was set in the anti-freezing design section. The polyurethane-corrugated steel plate insulation lining proposed in this paper is mainly composed of corrugated steel plate, polyurethane insulation layer and waterproof layer. The polyurethane-corrugated steel insulation lining is applied by using self-made rail flat battery car, door-type scaffolding, arch slide and other construction equipments. The on-site temperature test shows that the insulation effect is obvious. The polyurethane-corrugated steel plate insulation lining has the advantages of fast construction speed, good thermal insulation effect, preventing concrete from peeling off blocks, easy removal and replacement. According to the field temperature test, under the natural temperature outside the tunnel from −18°C to −22°C in winter of 2018–2020, the temperature of the interface between surrounding rock and lining of the tunnel monitoring sections are all above 0°C so that the freezing damage is eliminated from the root. Research results can provide a theoretical basis for the anti-freezing projects of tunnels in seasonal frozen area.