LAUSR

Abstract To study long-term strength characteristics under complex stress states, a series of hollow cylinder creep tests were conducted on frozen clay under different stress levels at a temperature of −6 °C. Experimental results showed that the creep characteristics of frozen clay were significantly affected by the mean principal stress and the intermediate principal stress coefficient. Most generalized shear creep curves of frozen clay presented typical non-attenuation creep under axial load and torque. A long-term strength criterion for frozen soil, exhibiting the strength characteristics of multiple stress components under complex stress states, was obtained based on activation energy theory. In addition, a modified elliptical function and a generalized nonlinear strength theory (GNST) were introduced to describe the evolution of the strength envelope with time. Finally, a new strength criterion for frozen clay in three-dimensional principal stress space, considering the effect of time, was established by combining the modified elliptical equation and the GNST shape function. The proposed strength criterion has great significance for predicting the strength characteristics of frozen clay under complex stress states.