Research on consolidation of frozen soils upon thawing

The settlement occurred on thawed frozen soil has much higher value than for unfrozen soils. The problem is actual considering the fact that permafrost is spread on 63% of territory of Mongolia. Significant settlement observed for structures of Khatgal, Ulaanbaatar and Nalaikh areas of Mongolia with coarse-grained clayey and sand soils requires laboratory investigation on thaw-deformation of frozen soils with regard to soil texture and thawing regime (initial pressure, temperature etc.). Furthermore, the great importance for the magnitude and nature of the settlement display the nature of physical processes upon freezing and thawing of soil. Theoretical hypothesis on physical phenomena and processes in thawing of frozen soils was formulated and then tested in laboratory conditions. Laboratory tests were conducted to determine the magnitude of settlement deformation upon thawing, in relationship with the clay content of samples, applied initial pressure, and heating intensities. Based on these tests it is possible to estimate the optimal load pressure for each type of soil. Within this threshold value of load pressure the soil deformations are limited to attenuating and eventually stabilized consolidation, but exceeding the optimal value leads to structural damages.