Mechanism Analysis of Subgrade Frost Heaving in Seasonally Frozen Regions

Abstract

To elucidate the frost heaving mechanism of subgrade, as well as reduce cracking, subsidence, and mudding due to water freezing and thawing in seasonally frozen regions, temperature sensors were embedded in the subgrade in a heavily frozen region to automatically monitor subgrade temperature during freeze periods. A drilling investigation was also conducted to determine the typical disease caused by road frost. Results show that (1) The upper roadbed exhibited a wide cooling range and a high cooling rate. (2) The lower roadbed exhibited a narrow cooling range and a low cooling rate; sufficient moisture transfer and accumulation occurred. The depth of the ice accumulation zone is found in this roadbed. (3) Different ice formations developed on various subgrade soils, and the depth and moisture content of these formations presented some regularity. (4) The mean depth of the ice accumulation zone was 1.08 m to 1.65 m, and the scope of mean moisture content was 14.7% to 23%. The maximum moisture content approached or exceeded the plastic limit of soil. Therefore, ice crystals separated, making up the majority of frost heave. On the basis of these findings, drainage and water block measures should be implemented to control subgrade moisture and enhance the management of the homogeneity and density of subgrade fillers. These measures will minimize and prevent frost-related problems.