Abstract
For coping with problems related to soil freezing and thawing, it is necessary to measure the frozen and melted depths accurately. In this paper, the time domain reflectometry (TDR) technique was applied to the measurement of both depths at a dry field lot in Fukagawa, Hokkaido, Japan. Then, the measured values by the TDR were compared with those by the temperature method using thermocouples and the methylene blue frost-tube, which have been used as a conventional method. As a result, it has been shown that the TDR is capable of measuring the frozen and melted depths in both the freezing and thawing processes with satisfied accuracy in actual use. Furthermore, it was found that the soil temperature gradient around 0°C is very gentle in the thawing process, consequently the temperature method is not so suitable for the same measurement in this process because it is difficult to locate the depth of 0°C line.
