Laboratory and theoretical investigations on the deformation and strength behaviors of artificial frozen soil

In order to study the mechanical characteristic of artificial frozen soils, such as strength, and stress–strain relationship, a series of triaxial compression tests of frozen sand has been conducted under confining pressures varying from 0.0 to 14.0 MPa with different water contents at − 6 °C. Frozen sand presents strain softening during shearing process under low confining pressures; but with increasing confining pressure, the strain softening decreases, and even presents strain hardening under high confining pressures. The strength of frozen sand is affected by water content and confining pressure. The strength with low water content always increases with increasing confining pressure; however, for frozen sand with a high water content, the strength experiences an increase followed by a decrease with increasing confining pressure. To describe the strength characteristic of frozen sand, the non-linear Mohr–Coulomb criterion, in which the generalized internal friction angle and cohesion under various confining pressures are obtained from experimental results, has been presented. The result shows that the non-linear Mohr–Coulomb criterion can reflect the decrease of strength of frozen sand under high confining pressures. The stress–strain relationships of frozen sand are represented by hyperbolic functions, which can describe both the strain hardening behavior of frozen sand under high confining pressure and the strain softening behavior under a low confining pressure.