A new off-wall insulation liner for high-speed railway tunnels in cold regions

This paper has designed a novel off-wall insulation liner, aiming to prevent severe frost damages for the high-speed railway tunnel in cold regions. In terms of composition, the double-layer steel corrugated plates of the liner not only prevent the block falling and water intrusion of cold-region tunnels but prolong the durability and effectiveness of thermal insulation materials. Besides, the quick-construction technology for the off-wall insulation liner was derived in the present study, and it exhibits excellent construction efficiency, great economic and social benefits in the highspeed railway tunnel. Concerning the insulation capacity, the double insulation layers (polyurethane foam and air) perform the dramatical coldness-blocking effect, the freezing line moves forward from 0.48m-deep surrounding rock to the lining surface. The four-year field test has proved the effectiveness and insulation capacity of the off-wall tunnel, the severe frost damages in the Wufengshan tunnel were successfully eliminated. Compared with existing coldproof measures, the off-wall insulation liner in this paper exhibits excellent insulation capacity, high construction efficiency, and excellent economic benefits, it could be applied in the high-speed railway tunnels with high-altitude or extremely low temperatures.