In China’s cold regions, insulation layers are commonly employed in numerous tunnels to mitigate frost-related damages. Nevertheless, despite these efforts, more than 70% of tunnels in these regions have been adversely affected by frost damage. This phenomenon is attributed to the cumulative freezing effect, which manifests when the minimum air temperature within the tunnel dips below 0 \(^\circ\) C, and the mean annual temperature falls below the initial temperature of the surrounding rock. Notably, when the temperature of the surrounding rock experiences a yearly decline, it results in freezing during the colder months, thereby exacerbating frost damage within the tunnels. This effect is attributed to the yearly accumulation of cold, which is a result of temperature cycles. Analyzing this effect and its impact on engineering is crucial for adopting effective frost-resistant measures. Research has been conducted using a temperature field numerical calculation model to study this effect under various conditions. The results show that conventional thickness insulation layers can prevent freezing in tunnels with a mean annual temperature greater than 2 \(^\circ\) C in high-altitude regions and 3 \(^\circ\) C in high-latitude regions. Low mean annual temperatures and their differences from initial ground temperatures are the primary causes of the cumulative freezing effect on cold-region tunnels. In the design of insulation layers for tunnels in cold regions, it is imperative to consider not only the mean temperature of the coldest month but also the mean annual temperature and its deviation from the initial ground temperature. When the cumulative freezing effect results in the failure of insulation layers in such tunnels, proactive measures to elevate both the mean annual temperature and ground temperature become crucial. By taking these factors into account, we can ensure a more effective and durable insulation design that can withstand the challenges posed by extreme cold conditions.
