Experimental Study of the Mechanical Properties of Coarse-Grained Soils from High Altitude and Cold Areas Under Freeze-Thaw Cycle

Experiments using GDS triaxial test apparatus were carried out on size-reduced coarse-grained soils with different moisture content (ω) (9%, 11.5%, 14%) and different dry density (ρ_d) (1.9 g/cm³, 2.0 g/cm³, 2.15 g/cm³) to study the mechanical properties under different freeze-thaw cycles (C) (0, 1, 3, 5, 7, 9, 12, 15, 20 times). The results show that the uniaxial strength of coarse-grained soils decreases with the increase of cycle times, and tends to be steady around 9 times, the deformation modulus of coarse-grained soils was gradually decreasing. With the increase of water content, the strength of coarse-grained soil was constantly decreasing, the deformation modulus was reducing. The stress-strain curves of coarse-grained soils were gradually changed from strain softening to strain hardening with the increase of moisture content, but the high dry density was an exception. With the increase of dry density, the strength and deformation modulus of the coarse-grained soils were increasing, and the slope of post-peak curve was increasing, the residual strength was also aggrandizing, and the strain softening was more obvious. Meanwhile, the strain hardening characteristic of high moisture content also changed to softening with the increase of dry density.