Mechanical Properties of Simulated Deep Permafrost

Creep tests were performed on frozen and unfrozen 20–40 mesh sand to evaluate the viscoelastic and yield properties of simulated deep permafrost. Overburden pressure associated with permafrost depth was imposed on samples by freezing under constant confining pressure and maintaining the pressure during the tests. The data showed that both thawed and frozen simulated permafrost behaved as a delayed elastic material before yield and as a coulomb plastic material after yield. The appropriate viscoelastic material constants were determined by correlating the test data with a mathematical model for the delayed elastic material. The results, together with Prudhoe Bay field test data, indicate that the creep response of deep permafrost, subject to loadings caused by thawing and refreezing, is negligible in comparison to the elastic and yield response.