Abstract: During the construction of core rockfill dam in cold regions in winter, it is an important precondition to quickly judge the freeze-thaw state of filled soil in the core to ensure the project's quality and the rapid construction. According to field tests, the infrared thermometric technique can be used to quickly detect the surface temperature and the freeze-thaw status of the core at long distance with a large area (more than 10 000 m²). However, under different ambient conditions, the error of surface radiometric temperature measured by infrared thermometric technique was 2-8 °C compared with contact temperature. In view of this, we conclude that environmental radiation and the surface emissivity are major factors that affect the error of infrared temperature measurement, of which the environmental radiation is mainly controlled by air temperature, while surface emissivity is affected by soil surface shapes caused by compaction patterns and geotextile covering. In association with field test data, we established the correction relationship between surface radiometric temperature and contact surface temperature. The research achievement provides important guidance for freeze-thaw detection technique of soil in engineering construction in cold regions.

Key words: core rockfill dam in cold regions, radiometric temperature, surface temperature, error analysis, correction model