| Abstract: | Heat transfer in freezing and thawing soils is accompanied by various processes among which phase transition of moisture and mass transfer should be distinguished in both the thawed and the frozen zones. Their consequence is the formation of ice schlieren and the swelling associated with this. In developing the methods of calculation of moisture migration it was assumed (see, for example, 1, 2]) that the mass transfer occurs only in the thawed part of the soil and is realized predominantly in the liquid phase through the diffusion-film mechanism. It was assumed that the phase conversion of water into ice occurs wholly on the phase interface (the Stefan formulation) and at the same time supplementary conditions for the moisture function are specified on it. Not all these assumptions are valid. In particular, the marked redistribution of moisture in the frozen zone is an important factor in the freezing of moist rocks 3, 4]. This last is also observed in the thawing of dispersed rocks and in frozen samples which are under the influence of a temperature gradient. These phenomena were modeled in 5, 7] on the basis of a single mathematical model which describes the conductive heat transfer, the moisture transfer in thawed and frozen zones, the phase transition of moisture in the temperature range, and the kinetic relaxation effects of moisture crystallization and ice melting. Analysis of the solutions obtained by means of a finite difference method showed that the proposed method of calculation gives results near the experiment. The present paper is devoted to a further study of the model indicated.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 2, pp. 113–120, March–April, 1986. |
