Investigation on the Effects of Freeze-Thaw Action on the Pore Water Pressure Variations of Soils

Freeze-thaw action changes soil microstructure and thus has a great influence on physical and mechanical properties of soils, which is closely correlated to pore water pressure (PWP). Herein, the PWPs of sandy soil and silty clay were measured in laboratory during freeze-thaw cycles (FTC). Experimental results showed that PWP was influenced by temperature, freeze-thaw history (i.e., number of freeze-thaw cycle), soil type and others. The PWP experienced a periodical change as temperatures periodically changes during the FTC testing, the PWP decreased during freezing and increased during thawing. Soil type has a slight influence on the variation of PWP, both in character and extent. A theoretical analysis of PWP in frozen soil was given to explain the PWP changes. In addition, the PWP depression during freezing was a major driving force for water migration. The PWP variations are highly relevant to the changes in soil microstructure such as soil particle (grain size composition and mineral composition), pore structure, and particle arrangement, which will be the focus of further research.