Research on dynamic compressive stress response of new type filler subgrade in freezing and thawing processes

Abstract

Abstract In this study, the dynamic compressive stress (DCS) response of a new type filler subgrade, which consists of oil shale residue, silty clay and fly ash, was studied during the freezing and thawing processes. Moisture content sensor, temperature sensors and DCS sensors were embedded in the outdoor subgrade model in the seasonally frozen region. Five loading points and three levels of load were set to investigate the effects of load on the subgrade in the horizontal direction and vertical direction during the freezing and thawing processes. Furthermore, distribution characteristics of DCS were analyzed by combining with the moisture content and temperature distribution diagram. The results show that:(1) The range of horizontal DCS response fluctuated significantly during the freezing and thawing processes. The maximum value emerged in thawing period and the minimum value emerged in frozen period. (2) The vertical DCS response was strongly affected by moisture content and temperature. The maximum value of DCS, the DCS variation rate along depth and the DCS variation caused by load change all occurred in thawing period. (3) Thawing period is the most unfavorable period for subgrade in seasonally frozen regions. Thus, moisture content and temperature conditions during the thawing period must be considered while optimizing and modifying subgrade filler in seasonally frozen regions.