Abstract: Tunnel frost damage during a full lifecycle in cold regions is challenging and should be addressed. Thus, based on the sensitivity of the freezing and frost heave of surrounding rocks, the development of freezing patterns and the distribution characteristics of frost-heave force in the surrounding rocks of the tunnel in cold regions are examined using numerical analyses and theoretical calculations, proposing a segmented frost-resistant design method. The findings are as follows: (1) The maximum freezing depth of tunnel surrounding rocks in cold regions during the full lifecycle rapidly increases in the early stages of operation and gradually stabilizes after that. The development speed of the freezing depth of the surrounding rocks is primarily related to the annual average temperature and the annual temperature amplitude. (2) The frost-heave force of tunnels in cold regions increases with increasing freezing depth. The maximum frost-heave force during the full lifecycle of tunnels in cold regions exhibits a significant longitudinal nonuniform distribution. (3) The segmented frost-resistant design based on the full lifecycle frost-heave force grading can minimize the risk of frost damage throughout the full lifecycle of tunnels in cold regions, improving the economic benefits of frost-resistant support.

Key words: tunnels in cold regions; frost-heave force, surrounding rock freezing pattern, segmented frost resistance, full lifecycle