Water and salt transfer coupled with phase change may cause serious damage to engineering structures in saline soil regions. In this study, the migration of water and salt in silty clay collected from the Qinghai-Tibet Plateau is explored experimentally and numerically during freezing and thawing processes. The results revealed that there are significant differences in the variations of liquid water content and solution concentration for different initial salt contents, due to salt crystallization and dissolution. The temperature-induced water migration is determined by the soil properties, which can be well explained by the thermodynamics of mass transfer. The amount of salt migrated upward during cooling is slightly larger than that transported downward in the warming period, implying that salt may be accumulated in the surface soil after a large number of circulations and finally result in soil salinization.

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To determine the stress and damage state of rock mass is important for many geotechnical engineering. To study the feasibility of resistivity measurement in characterizing the damage and stress state, the resistivity measurement, uniaxial compression test, and incremental loading–unloading compression test were carried out on granite samples with different porosities (induced by different treatment temperatures). Results show that the resistivity is very sensitive to thermal damage and mechanical damage during compression. The evolution of resistivity can not only quantify thermal damage but also clearly indicate the critical stress (crack closure stress and crack damage stress) and damage stage during compression. In addition, the resistivity evolution was quite different in the pore closure stage, elastic deformation stage, and unstable cracking stage during the loading–unloading process, which is useful in field stress and damage state identification for field monitoring. The conductive mechanism variation during compression was discussed using the Archie equation considering crack volume strain evolution during the mechanical damage process. Overall, the resistivity measurement holds great potential in geotechnical engineering for field monitoring.