Field measurement of air temperature in a cold region tunnel in northeast China

In this paper, a comprehensive measurement of air temperature in Zuomutai tunnel in China was conducted. Meteorological monitoring was performed at both outsides of the tunnel. The results show that the air temperature in the whole tunnel changes periodically with the ambient air temperature out of the tunnel in an approximately trigonometric function, even if the tunnel length is approximately 3000 m and the height is 7.1 m. The lowest temperature is lower than -8 degrees C. In winter, the air temperature outside the tunnel is lower than that inside the tunnel, which causes the dominant airflows from the low elevation portal to high elevation portal. It is contrary in summer. Therefore, the temperature changes in the sections at the two sides of the tunnel are different, and the temperature distributions are asymmetrical along the tunnel length. The air temperature at the tunnel vault is generally higher than that at the waist and side wall in winter, especially nearby the dominant airflow outlet. With the temperature rising, the temperature difference decreases. The sharp rises or drops of air temperature in the tunnel caused by the intermittent traffic winds or natural winds blowing to the tunnel are transient. The air temperature will soon return to the overall change trend. The results can provide references for frost-proof design in cold region tunnels.