Selection of Construction Materials for a Thermal Insulation Layer of a Road

Abstract

Safety of the roads in the permafrost region is largely determined by their thermal regime. The aim of the present work was to discover a function to determine the thermal conductivity coefficient of materials used to construct a thermal insulation layer of a road to prevent foundation soils from thawing over a permitted thawing depth. Two cases were surveyed: when the natural temperature of the soil is equal to ice melting temperature and when it is not equal to ice melting temperature. Engineering formulas permitting to quickly select the required thermal resistance property of an insulation material based on the known Biot number were derived. An expedient regularity is observed: the thermal resistance of the thermal insulation layer is roughly proportional to the dimensionless thawing depth. Correspondingly, when selecting the construction materials for a thermal insulation layer it can be considered that the increase in permissible thawing depth increases proportionally to the increase of the thermal conductivity coefficient of the insulation material. Considering that the physical and mechanical properties of the soil are not constant along the road length, the thermal resistance of the thermal insulation layer should be determined for individual sections of the road rather than for the entire route. Accordingly, the construction materials can also vary depending on the selected solutions for the road construction.