FIELD EXPERIMENT ON DISTRIBUTION CHARACTERS OF AIR TEMPERATURE AND GROUND TEMPERATURE IN KUNLUNSHAN TUNNEL OF QINGHAI—TIBETRAILWAY

Several sections were set up to observe the air temperature and ground temperature in Kunlunshan tunnel. Based on the observed data,the distribution characters of the air temperature,ground temperature,and temperature on two sides of an insulation layer in this tunnel,were analyzed. It is found that (1) air temperature on the top is higher than that on the bottom of the tunnel,and air temperature is lower at the end of tunnel than that in the center of the tunnel. The influence of air temperature outside tunnel gradually becomes weaker as the distance from entrance and exit increasing;(2) ground temperature linearly decreases with the depth along surrounding rocks increasing and it becomes negative at a certain depth;(3) the thawed areas appear in the rocks surrounding the tunnel after excavation and the thickness of thawed areas is mainly influenced by air temperature;and (4) the effect of thermal insulation of insulation layer is good for tunnel in cold regions.