Principle of thermal insulation for permafrost protection

In permafrost regions, the measures of constructing embankments or installing thermal insulations are in common use to keep the permafrost table under the roadways stable. However, the effectiveness of these measures depends on their adjustment to the mean annual ground temperature and the temperature amplitude in the permafrost under the roadway. This paper explains the principle of thermal insulation for permafrost protection. Based on the principle, the probability of the existence of maximum and minimum embankment heights and the applicability of thermal insulation are discussed. The principle is well confirmed by the observational field data at the Beiluhe test site on the Qinghai–Tibet Railway.