A convection-conduction model for analysis of the freeze-thaw conditions in the surrounding rock wall of a tunnel in permafrost regions

Based on the analyses of fundamental meteorological and hydrogeological con ditions at the site of a tunnel in the cold regions, a combined convection- conduction model for air flow in the tunnel and temperature field in the su rrounding has been constructed. Using the model, the air temperature distri bution in the Xiluoqi No. 2 Tunnel has been simulated numerically. The simu lated results are in agreement with the data observed. Then, based on the i n situ conditions of air temperature, atmospheric pressure, wind force, hyd rogeology and engineering geology, the air-temperature relationship between the temperature on the surface of the tunnel wall and the air temperature at the entry and exit of the tunnel has been obtained, and the freeze-thaw conditions at the Dabanshan Tunnel which is non under construction is predi cted.