Creep deformation and heterogeneous characteristics for frozen soils with thermal gradient

Triaxial creep tests on frozen clay are conducted by using the K₀DCGF (K₀ consolidation, freezing with non-uniform temperature under loading) method under various thermal gradients. The creep deformation and heterogeneous characteristics of the frozen clay with thermal gradient are investigated. The test results indicate that the frozen saturated clay with thermal gradient presents brittle characteristics in creep tests, and the creep curves are composed of transient creep stage, attenuation creep stage and accelerated creep stage. The radial creep rate is smaller than the axial one. The relationship between the minimum axial creep rate and the creep stress can be expressed by the exponential equation, while that between the long-term strength and the creep failure time can be described by the logarithmic equation. The redistribution of the water content before tests and the non-uniform deformation distribution after tests are the specific form of the heterogeneous characteristics caused by the thermal gradient. The water content and the density at the lower temperature end are the largest. The ratio between the radial deformation and the specimen height increases as the specimen height increases, and it decreases as the specimen height increases further under lower creep stress. However, the ratio between the radial deformation and the specimen height presents a continuous increase trend as the specimen height increases under higher creep stress. This phenomenon is related to the initial transient creep rate.