Internal temperature measurement-based supplementary guidance for the Japanese geotechnical society's frost heave testing method

Building on permafrost necessitates a comprehensive assessment of frost heave, which can be evaluated using standardized testing methodologies. The Japanese Geotechnical Society (JGS) has developed a frost heave testing method that offers efficiency in specimen preparation and methodological rigor. However, uncertainties in determining frost heave rates persist. This study investigates frost heave behavior under various boundary temperature conditions using soil samples with differing frost heave susceptibilities, while comprehensively reviewing the JGS experimental methodology. By evaluating frost heave behavior according to the JGS standard with a temperature control unit, this study aims to enhance reliability through internal temperature monitoring and cross-checking key parameters. The methodology for calculating frost heave rates was refined, focusing on an optimal evaluation period within the 10 to 20-hour range. Results indicate that controlling freezing rates and experimental time is crucial to align with JGS requirements. This study provides additional guidance to determine frost heave rates, proposing a refined 20-hour freezing duration to improve the efficiency, certainty, and consistency of frost heave testing. The findings highlight the importance of precise boundary conditions control and key parameters including freezing rate, freezing time, frost heave ratio, and bottom freezing speed determination in the JGS test method, providing a more reliable framework for engineering assessments.