Creep strength of Ottawa frozen sand under varying mean stress

Studies were carried out on the creep strength of Ottawa fine sand at -3.89°C under triaxial compression. The time-dependent strength of the frozen soil under multiaxial stress state is described by a parabolic creep strength criterion. In the particular case of the small stress domain, the parabolic yield criterion transforms into a generalized (for creep conditions) Drucker-Prager strength criterion. The latter, which was originally developed by this author to describe the strength of frozen soil when mean normal stress was constant, is expanded in the paper over a stress state at which the mean normal stress changes with time in accordance with the curve of the long-term strength (time-dependent failure). It is shown that if the rheological parameters of frozen soil are known, the above criterion describes the long-term strength of soil under a multiaxial stress state at constant and varying mean stress.