Numerical Research On The Coupled Mechanism Of The Moisture-heat-stress Fields In Freezing Soil

The coupled mechanism of the moisture-heat-stress fields is an extremely complex problem concerning thermodynamics, hydrodynamics, fluid mechanics, physics and chemistry in the process of freezing and thawing of the soil. The special characteristics of the frozen soil, especially the emergence of ice lens, make the research of the frozen soil more complex than the common soil. To prevent and control the phenomenon of frost-heaving and thawing-settlement during freezing and thawing of the soil, sufficient attention should be paid to the coupled mechanism of the moisture-heat-stress fields.Based on the model of Harlan, this paper synthetically considers the hypothesis of rigid ice and the model of hydrodynamics, and regards the soil as elastic. Most of the earlier scholars treat the ice content as a coupled factor. This paper simplifies the moisture-migration-equation through substituting equivalent water content for ice content, adopts ice-impedance-factors to solve calculation-parameter, uses apparent heat capacity to deal with phase change latent heat, and considers the influence of soil strain on the water content. The model of the coupled moisture-heat-stress field in freezing soil is established.At the end of this paper, FEM and FDM are employed to solve the coupled equation of the moisture-heat-stress field during the freezing of the saturated soil, simulate the freezing process of soil-pole and frozen bed, and summarize the laws of water-content-distribution and the stress distribution, and the influence of frozen time, temperature boundary on water-content-distribution and the stress distribution. From analysis of the results, the conclusion is drawn that it is effective to protect the stability and the security of buildings in the frozen region through heat preservation and temperature control of the bed.