The active development of the northern latitudes leads to the fact that a significant number of sources of technogenic heating arise in the permafrost regions. This shifts the existing thermal equilibrium and leads to gradual thawing of the frozen phase in the medium. This process can significantly reduce the strength of the geological massif and lead to subsidence of the soil surface, depletion of the bearing capacity of the soil, and eventually to the occurrence of landslides and sinkholes. This paper is devoted to the numerical modeling of partially melted medium in the permafrost region. The paper covers mechanical processes in the soil under static gravitational load, taking phase composition space distribution as the input. The multiphase medium is described using Biot model with the effective parameters for a composite solid phase and separate parameters for a fluid phase. The numerical solution is obtained using finite element method that is also presented in the paper. Calculation results for several two dimensional problem statements are presented and discussed in the paper