Mechanical behavior and improved hypoplastic constitutive model for saturated frozen sand

The artificial ground-freezing method is the main technical means for the excavation of mines and tunnels through the water-rich sand layer, and the comprehensive understanding of the mechanical properties of frozen saturated sand and the stress-strain relationship under complex stress can provide important guidance. In this study, a series of true triaxial tests of frozen saturated sand samples were conducted. Combined with the test data, the effects of temperature and medium principal stress ratio (b) on the strength and deformation characteristics of frozen saturated sand are discussed. In addition, a cohesion tensor is introduced to the Wu-Lin hypoplastic model. A scalar value is used to characterize the effect of temperature on the strength of frozen soil. The defect that the original model cannot describe the tensile capacity of frozen soil under low stress conditions is clearly solved. In addition, the cumulative deformation state variable is introduced to improve the response performance of the model in triaxial compression tests. The hypoplastic model of frozen soil has shown good performance in simulating triaxial compression tests at different temperatures and medium principal stress ratios.