Abstract: To investigate the longitudinal temperature field distribution patterns and influencing factors of tunnels located in cold areas, a case study is conducted on the Xianfeng tunnel of the HarbinMudanjiang highspeed railway, and a threedimensional fluidsolid thermal coupling model is established for cold area tunnels. Variables such as ventilation time, equivalent wind speed, and wind temperature are used to investigate the longitudinal temperature distribution trends and variations in these tunnels. Ultimately, a calculation formula for the longitudinal tunnel temperature in cold area tunnels is derived. The main conclusions can be summarized as follows: (1) The temperature inside the tunnel increases and then decreases as one moves further. (2) The temperature in each tunnel section in the cold area gradually decreases with increasing ventilation time, eventually stabilizing after 60 days of ventilation. (3) 〖KG-*9〗〖JP3〗The temperature in the longitudinal〖JP〗 direction of the tunnel decreases with increasing equivalent wind speed. (4) The inlet wind temperature directly impacts the tunnel′s temperature field, but its influence weakens as one moves further into the tunnel.

Key words: tunnels in cold areas, longitudinal temperature field, ventilation time, holeentering wind temperature, equivalent wind speed