Boundary conditions for modeling the ground thermal profile near shallow culverts

Abstract

Abstract Culverts create disturbance in the ground thermal regime in cold regions below pavement structures. The thermal disturbance caused by culverts may result in geotechnical problems such as permafrost degradation, frost heave, and differential settlement which impact road roughness and road safety. Thermal numerical modeling of shallow culverts below a pavement structure requires accurately defining boundary conditions for the road surface. This study evaluates five empirical pavement temperature methods used as the pavement surface boundary condition in a 2D numerical model that predicts the soil temperature below pavement surfaces over shallow culverts. The predicted soil temperatures from the numerical model are validated with two years of measured soil temperatures at five instrumented culvert sites. The predicted soil temperatures are evaluated through trend analysis and statistical F-test at 95% confidence. A pavement surface boundary condition obtained from each of the five pavement temperature methods is considered successful when the difference between the predicted and measured values pass the F-test for all seasons over the two-year study period. The results of the analysis show that three of the five pavement temperature methods passed the trend and F-test analysis. The three pavement temperature methods more accurately defines the boundary conditions for the road surface and are utilized in the numerical model to predicted frost penetration depth below the pavement surface and near the culvert openings. The findings from this study are expected to increase the accuracy of modeling the frost heave and the differential thaw settlement under pavement structure due to the influence of culverts.