The objective of this study was to investigate the physical-mechanical characteristics of frozen Siberian silt. Unfrozen water content, uniaxial compressive strength and direct-tensile strength of frozen silt samples at different moisture contents were determined in the laboratory. Experimental results revealed that the amount of unfrozen water in the silt decreased with descending temperature and stabilized at temperatures below -10 o C. Even at very low temperatures a considerable amount of unfrozen water remained. Mechanical strength test results showed a strong dependence of the stress-strain behavior of the frozen silt on the moisture content and temperature. The strength for compression and tension increased with decreasing temperature and increasing moisture content. At any given temperature and moisture content compressive strength was significantly greater than tensile strength. Based on the compressive and tensile stress-strain relationship at a given temperature and moisture content, approximate values of strength ratio, failure strain ratio and deformation modulus ratio were established.

The influence of temperature and Freeze-Thaw (FT) processes on the mechanical properties of frozen soils were investigated in the laboratory in order to give a better understanding of changes in engineering properties of frozen soils. The experimental data revealed a dependence of compressional and shear wave velocity of frozen soils on temperature, soil type and FT cycles. Compressional wave velocity showed a strong correlation to the unfrozen water content dependent on soil type, while shear wave velocity was mainly influenced by the ice content and the soil matrix. Compressional and shear wave velocity changed for samples subject to FT cycling, which appears to be caused by alterations in the soil structure. Elastic constants were calculated based on the wave propagation theory and compared to results from uniaxial compression tests. The dynamic elastic modulus, dynamic shear modulus and compressive strength increased with descending temperature. FT cycles reduced the compressive strength, and influenced the dynamic elastic constants. Poisson's ratios of all tested soils not subject to FT cycling decreased upon a change in negative temperature; while the opposite trend was observed for soils influenced by FT cycles.

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