Size effect of temperature field in large tunnel subjected to freeze-thaw disasters

The change in size (transverse section and longitudinal length) of a tunnel will result in variation in the temporal and spatial distribution characteristics of the tunnel temperature field, particularly in the cold region. Understanding the size effect on the temperature field is crucial for the prevention of freeze-thaw disasters in large tunnels in high-altitude frozen soil areas. This study investigates the distribution of the tunnel temperature field, considering traffic wind through numerical simulations. The research explores how changes in size affect both the temporal and spatial distribution of tunnel temperatures and freeze-thaw depths. The findings reveal that traffic wind significantly influences tunnel temperature fields, with larger amplitudes observed when accounting for traffic wind compared to no-traffic wind conditions. Additionally, peak temperature of surrounding rock decreases logarithmically with increasing tunnel diameter and depth, while freeze-thaw depth decreases logarithmically with increased section size. Furthermore, the peak temperature of surrounding rock and the freeze-thaw depth are inversely proportional to the tunnel length. Based on these observations regarding section size and length's impact on temperature fields, a mathematical relationship between freeze-thaw depth within surrounding rock and tunnel dimensions is established to elucidate the size effect on temperature fields. These research results could provide theoretical guidance for the design, construction, and disaster prevention of tunnels in alpine regions. • Temperature field of tunnel in cold area under the action of traffic wind is studied. • Size effect of temperature field for the large tunnel in alpine region is revealed. • A mathematical expression of tunnel radial freeze-thaw depth is established.