Coupled Hydraulic-Thermal Model for Soils under Extreme Weather in Cold Regions

Abstract

Extreme weather conditions govern the hydraulic and thermal properties of glacial clay deposits under the cold climate of the Canadian Prairies. The prediction of time-dependent soil behavior over the entire year and under extreme weather conditions is required for the design and construction of buried infrastructure. The main contributions of this research are the development and validation of a coupled soil-atmosphere interaction model to predict transient water and heat movement under mean, extreme dry, and extreme wet weather scenarios. Results indicated that the hydraulic properties are governed by the net water flux that resulted in the shifting of the seasons as follows: mean that comprises winter (3½ months), spring (1 month), summer (5½ months), and fall (2 months); dry that includes spring (4 months), summer (4 months), and fall (4 months); and wet that has winter (4 months), inseparable springsummer (5 months), and fall (3 months). The thermal properties are governed by air temperature for the investigated soil. Identical values of thermal gradient during spring-summer (April to October) in all scenarios indicate that the soil gains more heat compared with the heat loss during fall-winter (November to March), especially for mean and dry conditions. Furthermore, the inflection points in heat flux show that the soil gains heat from May to August and loses heat from September to April. Finally, the active depth of soil was found to be 4 ± 1 m for hydraulic properties and 3 m for heat flux.

Keywords: climate interaction, hydraulic flow, thermal flow, numerical modeling