Tunnel temperature fields analysis under the couple effect of convection-conduction in cold regions

Abstract

This paper performs a similarity simulation model test with 1:30 geometric scale based on practical horseshoe railway tunnel section to investigate the couple effect of convection-conduction with low inlet temperature airflow. The low inlet temperature is produced by refrigerating system. The results show that the temperature of airflow and surrounding rock drop rapidly at the beginning of the test and then slow down with time; the closer to the entrance of the tunnel, the strongly temperature changes of airflow and surrounding rock will be; temperature of airflow and surrounding rock fluctuate with the changes of inlet temperature, but the fluctuation is hysteretic. Then, the tested results are compared with finite difference calculated results and temperature fields are analyzed under different inlet temperature, ventilation velocities and mechanical ventilation. It can be seen from the results that, tested results agree well with finite difference calculated results; the higher the ventilation velocity and the lower the inlet temperature are, the more rapidly the temperature reduction will be; in the positive ventilation direction, high mechanical ventilation velocity (higher than natural velocity) has adverse effect on freezing damage in tunnel; negative ventilation direction, to some extent, does good to alleviate freezing damage.