Suction Measurement in Freezing Process Using High-Suction Tensiometer

Frost heaving is a major cause of damage to infrastructure in the seasonal freezing area. It is well known that the heaving is caused by the freezing of moisture migrated to the frozen front in response to the suction force instead of freezing of in situ only. Researchers have been trying to measure the suction force of the freezing soil and obtained a soil-freezing characteristic curve (SFCC) which is similar to the soil-water characteristic curve (SWCC) in unsaturated soils. However, a direct suction measurement in freezing soil is still a challenge. In this study, a high suction tensiometer (HST) developed for matric suction measurement in unsaturated soils was used to measure the suction in the freezing soil. Six thermocouples were installed in the soil to monitor the temperature variation of the different location of the soil. The experiment design, procedures are addressed in detail. The results revealed that 1) suction generated in the soil when water freezes during the freezing process, 2) HST can successfully measure the suction variation in the process of soil freezing, 3) suction increases dramatically when the water freezes to a certain degree, 4) temperature variation at the different location indicated that moisture migration happened in the freezing process.