One of the geomechanics challenges is the quantitative assessment of deformation of soils associated with frost heaving and thawing. The main difficulty in solving this problem is the need to consider changing the state of soil freezing and thawing ground and thermophysical characteristics of the medium in a transient state. The main process in frozen soil is the redistribution of moisture in them due to water migration during freezing. When water freezes, the soil characteristics, its physical and mechanical properties change. This paper includes description of a numerical simulation method and study about humidity changing in frozen soils, depending on the rate of soil freezing. The influence of soil humidity changing on the values of strength characteristics during the process of thawing is evaluated. The developed technique of numerical simulation of the freezing and thawing process allows assessing the impact of frost heaving forces, decreasing the strength of buildings foundations and structures during freezing and thawing at the design stage. This allows the effective implementing of modern structures for soils and foundations reinforcement using geosynthetics to reduce or eliminate frost heave processes and thawing.