Thermal conductivity of snow cover

Abstract

Important parameters when using snow as a building material and designing the interaction of engineering structures for various purposes with snow are the density and coefficient of thermal conductivity of the snow cover. The purpose of the article was to evaluate the accuracy of calculating the thermal conductivity coefficient of a two-layer snow cover, depending on the degree of compaction of one of the layers. Two approaches to determining the thermal conductivity coefficient are considered: as a layered structure and as an equivalent homogeneous structure having a constant average density. Classical formulas for determining the coefficient of thermal conductivity from density (Abels formula) and density from the depth of snow cover (Abe formula) were used for calculations. As a result of the analysis and complex variant calculations presented in the form of graphs, the following conclusions are made. With a linear dependence of the thermal conductivity coefficient on the density of snow, the choice of one or another method for calculating the thermal conductivity coefficient of a two-layer snow cover does not matter: an error in calculations will always be zero. With a nonlinear dependence of the thermal conductivity coefficient on the density of snow, the error increases with an increase in the compaction coefficient of one of the layers. For example, with a compaction coefficient of 1.5, the relative calculation error does not exceed 4%. And with an increase in the compaction coefficient to 3.5, the error increases to 31%. That is, it increases almost 8 times. The analysis of the results allowed us to conclude that when compacting one of the layers by less than 2 times (compaction coefficient k<2), the use of the concept of “average density of snow cover” in thermal calculations to determine the thermal resistance of snow cover is quite acceptable. With an increase in the degree of compaction of one of the layers by more than two times, it is necessary to determine the thermal conductivity coefficient of each layer and calculate the total thermal snow cover as the sum of the thermal resistances of the individual layers.