GEOTECHNICAL PROPERTIES OF SUBGRADE SOILS DAMAGED BY FROST HEAVE

Abstract

 We collected 48 samples of subgrade soil from a frost-heaved place of a national road in Hokkaido and investigated them for both frost susceptibility and geotechnical properties. We found that more than 80% of the subgrade soil samples taken at frost-heaved locations were coarse-grained, and many were of high quality suitable for compaction. An experiment of the variation in the fine fraction of such samples, however, revealed cases of marked variation over stretches of several hundred meters, raising concerns that differential frost heave could result in an uneven or bumpy roadway surface. None of the subgrade soil samples collected from the frost-heaved locations was judged to be non-frost susceptible. Most were instead judged to be frost susceptible, with many having high frost susceptibility. We examined several indices to determine their suitability as convenient measures of frost susceptibility and found that combination of ignition loss (a qualitative indicator of frost-heave susceptibility) and a fine fraction (a quantitative indicator of frost-heave susceptibility) was effective.