Use of Rigid Geofoam Insulation to Mitigate Frost Heave at Shallow Culvert Installations

Abstract

Roadways over culverts experience severe distresses due to frost action in the subgrade. Thermal insulation placed near the culvert can reduce frost penetration in the soil surrounding the culvert. Three culvert sites backfilled with clay in Manitoba, Canada were instrumented with thermistors to monitor the changes in the soil thermal profile near culverts with and without thermal insulation placed below the culvert barrels. Temperature data from the instrumented sites were used to calibrate and validate a two-dimensional (2D) numerical model which was used in evaluating the performance of different placements of thermal insulation near culverts through a parametric study. The parametric study included evaluation of the use of thermal insulation above the culvert, below the culvert, and attached to the walls of culvert barrels to reduce the thermal disturbance in the soil. It was concluded that the least thermal disturbance in the soil was achieved when 75-mm thermal insulation was attached to the walls of the culvert. The outcomes of this study can be used to mitigate road roughness over culverts that is caused by frost action.