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| Name of tunnel | Engineering overview | Temperature field information | Antifreeze insulation measures |
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| Dabanshan tunnel [34–36] | Length: 1530 m; altitude: 3650–3900 m; location: Hinterland of Qinghai-Tibet Plateau; completion time: November 28, 1998; monthly average minimum temperature: −25.6°C; the maximum depth of frozen is 4.5 m. | (1) When the temperature in the tunnel is −12°C, the surface of the concrete upper lining is 0.2°C–0.5°C. (2) The temperature in the tunnel in the cold region changes regularly along the depth, which is approximately a parabolic distribution. | (1) There is no pressure cold-proof drain tunnel under the tunnel’s main hole. (2) The tunnel’s surface insulation layer is rigid foam profile and rare earth insulation material. (3) The tunnel outlet insulation door, the tunnel outside the circular end buried thermal insulation outlet. |
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| Xiaopanling tunnel [37, 38] | Length: 655 m; temperature altitude: 3000 m or above; location: Yanbian city, Jilin Province; completion time: 2000; annual minimum temperature is −38°C; the maximum depth of frozen is 1.8 m. | The analysis shows that the maximum frozen depth of surrounding rock changes little along the whole length of the tunnel with a length of about 600 m, and the frozen depth outside the tunnel is larger than that inside the tunnel. | (1) The antifreeze scheme is designed with drainage as the core, using high-quality waterproof materials, as well as wave-shaped longitudinal drainage pipes. (2) The drainage technology measures such as thermal insulation outlet are set, and the waterproof and drainage effect of the tunnel is significantly improved. |
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| Fenghuoshan tunnel of Qinghai-Tibet railway in China [39, 40] | Length: 1338 m; altitude: 4905 m; location: Hinterland of Qinghai-Tibet Plateau; completion time: October 19, 2002; annual average temperature: −7°C; annual minimum temperature is −41°C. | (1) The ground temperature of surrounding rock behind the tunnel changes linearly with time and depth. (2) The melting range and the temperature ratio in- and outside the tunnel change linearly during the construction of permafrost tunnel. | (1) Strengthen the comprehensive prevention and control measures such as waterproof and drainage, application of heat insulation, and insulation technology. (2) Carry out low-temperature grouting on surrounding rock to achieve the purpose of blocking bedrock fissure water. (3) Set up thermal insulation ditch in the tunnel to lead and drain the water behind the lining. |
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| Zhegushan tunnel on the 317th National Highway [41–44] | Length: 4424 m; altitude: 3500 m; location: Western Sichuan Plateau; completion time: December, 2004; the annual average snow days is 105 d; the maximum snow depth is 0.47 m; historical lowest temperature is −31.1°C; the maximum depth of frozen is 1.01 m. | (1) The temperature change in- and outside the tunnel is periodic, which can be fitted by sine function regression method. (2) After the tunnel is through, the average temperature inside the tunnel decreases by 3-4°C, after the tunnel is through, the air flow has an impact on the temperature distribution inside the tunnel. | (1) In the length range where frost damage may occur, the heat insulation layer with surface heat insulation treatment shall be adopted. (2) The proper drainage system shall be adopted, the deep buried water or cold proof ditch shall be adopted to prevent the water discharged from the tunnel from overflowing and road freezing in the portal section due to the inability to discharge from the tunnel. |
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| Qingshashan tunnel | Length: 3350 m; altitude: 3044–3398 m; location: Qingshan mountains are in Qinghai Province; completion time: August 2004; the annual average temperature is 5.9°C; the annual extremely low temperature is −26.6°C; the maximum depth of frozen is 1.48 m. | The temperature inside the tunnel lining presents an inverted “U” distribution along the longitudinal direction of the tunnel. The temperature rise at the entrance of the tunnel is small, while the temperature rise at the exit is large. The main influencing factor is that the wind speed in the tunnel increases with the depth of the surrounding rock. | (1) Cold proof ditch shall be set at the two tunnel openings, respectively, and the distance from the ditch to the outside of the tunnel shall be more than 20 meters. (2) In addition, multiple sets of electric heaters are set in the cold proof ditch to relieve the freezing of drainage channel. (3) Within the length of the hole where freezing damage may occur, the surface heat insulation layer shall be used. |
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