Experimental study on the creep behavior of frozen clay with thermal gradient

Thermal gradient is one of the main features in frozen engineering, especially in artificial frozen wall (AFW) in deep alluvium. This paper investigated the creep behaviors of frozen soil with thermal gradient. A series of uniaxial creep tests were carried out on frozen saturated clay under various thermal gradients and creep stresses by GFC (freezing with non-uniform temperature without experiencing K0 consolidation) method. Two stages were observed during the whole creep process, i.e., instantaneous elastic deformation and decaying creep deformation. Radial creep deformation of ε3 almost increases linearly with an increase in axial creep deformation of ε1, and the slope of ε3–ε1 curve increases as the thermal gradient (or creep stress) increased. Long-term strength decreases as the thermal gradient (or the creep time) increased. Considering the correction equation on thermal gradient, the generalized Kelvin model consisting of one Hooke element and two Kelvin elements has been developed to describe the axial creep deformation. The validity of the model is verified by comparing its calculated results with the results of creep tests under both low and high thermal gradient. It is found that the axial creep deformation behavior of frozen saturated clay can be represented by generalized Kelvin model, and the proposed model reflects thermal gradient effects to the creep deformation well.

► Uniaxial creep curves consist of two typical stages.
► Relationship between radial and axial deformation satisfies linear model.
► Long-term strength decreased as thermal gradient increased.
► Creep behavior can be well described by generalized Kelvin model.