Road foundation thawing at change in Ice content along the active layer depth

Abstract

The seasonal temperature and humidity regime of the road foundation in the active layer of soil largely determines the reliability and safety of the automobile road use. The aim of this article is a quantitative assessment of the influence of variation in ice content in the active layer of the road foundation soil in the permafrost area on the depth of seasonal soil thawing. Analytical solutions of one-phase flat Stefan problem at varying ice content along the coordinate were obtained. The solution is in the dimensionless form as a Fourier function based on Stefan number and dimensionless simplexes. The dependence of ice content change on the distance was assumed to be linear. Calculations using the obtained formulas were conducted, comparing against formulas assuming that ice content is a constant. It was determined at which ice content gradient averaging the ice content does not lead to an error greater than permitted in engineering practice in determination of the thawing depth. The results of variant calculations are presented as 2D and 3D charts to assess the influence of the initial ice content in the soil and the degree of its variation over the period of road use on the thawing depth of road foundation.