Effects of initial soil-water conditions on frost heaving characteristics

Frost heavings have been observed on the soils in waterproof basins (four basins denoted by A, B, C and D) at the Tomakomai field site, Hokkaido, Japan. Basins A, B and C were filled with the same silty soil, and Basin D with four layers, namely, pebbles (0–5 cm below the surface), a mixture of pebbles and silty soil (5–20 cm), silty soil (20–60 cm) and sand (60–160 cm). In the winter of 1976–1977 water levels in the basins were set at the levels of the ground surface in A, 40 cm below the surface in B, the bottom in C and 30 cm below the surface in D. Basin C had no free groundwater. The highest surface heave was 32 cm in A, 26 cm in B, 19 cm in C and 14 cm in D. A water supply from the free groundwater toward the freezing front extended over 220 cm through the silty soil, but was limited to 63 cm through the sand. The migration speeds of the soil water supplied from the unfrozen part were calculated for A, B and C from the measurements of their volumetric water-content profiles.