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Table 5 Assessment standard of extreme freeze-thaw days in cold regions

From: Analysis methodology and assessment indices of vulnerability for asphalt pavement in cold regions

Assessment Index Micro Mild Moderate Severe Extreme
Freeze-thaw days (d) < 54 54 ~ 60 60 ~ 66 66 ~ 72 ≥72
The frequency of blizzard < 0.2 0.2 ~ 0.4 0.4 ~ 0.6 0.6 ~ 0.8 ≥0.8
Permafrost temperature (°C) <−3 − 3 ~ −1.5 −1.5 ~ −0.5 − 0.5 ~ 0 > 0
Ice content of permafrost S, D, F S, D, F S, D, F S, D, F B, H
  1. 1) S refers to less ice, D refers to more ice, F refers to rich ice, B refers to saturated ice, and H refers to soil ice. 2) When a certain ground temperature is combined with B or H, it should be classified as the next level. For example, when the permafrost temperature is lower than −3 °C and the ice content is B or H, the exposure is mild