Investigating the stress-strain behavior of frozen clay using triaxial test

Temporary soil improvement methods have always been a concern of geotechnical engineers. Today, the use of methods such as nailing and anchorage is one of the common methods in Iran, while in developed countries, new methods such as artificial ground freezing are also used. The reason for the increasing use of artificial ground freezing, in addition to technical, economic and environmental benefits, is its ability to be used in all boundary conditions and all types of soils. Due to the insignificant laboratory study on the behavior of frozen clay, in this paper, after conducting initial experiments, over 130 unconsolidated-undrained triaxial experiments have been performed on clay samples prepared from the Shurabil Lake site (located in Ardabil). In these triaxial experiments, the effect of freezing, temperature decrease, strain rate increase and confining pressure increase on stress-strain behavior of saturated clay samples has been completely investigated. The results of this study show that decreasing the temperature significantly increases the shear strength and modulus of elasticity of frozen clay samples. Also, due to the presence of ice matrix in the structure of frozen clay, the effect of strain rate is to a large extent, which leads to an increase in shear strength and modulus of elasticity of the samples. Also, all samples showed strain hardening behavior and none of the samples showed brittle rupture. Therefore, the use of artificial ground freezing method in clay soils can be used.