Dynamic Properties of Expansive Soil-Rubber under Freeze–Thaw Cycles

Soils mixed with recycled waste rubbers have been widely used in geotechnical and geoenvironmental engineering. However, the research on rubber-soil mixtures in deep seasonally frozen regions is relatively lacking, so the application and dynamic properties of expansive soil-rubber (ESR) undergoing freeze–thaw (FT) cycles need further investigation. This study investigated the dynamic properties of ESR undergoing freeze–thaw cycles in terms of confining pressure and frequency using temperature-controlled dynamic triaxial tests. The results show that (1) shear stress and dynamic shear modulus with 5% and 10% rubber content (RC) are similar under freeze–thaw cycles, and both decrease and then increase with the number of cycles; (2) shear stress and dynamic shear modulus are positively correlated with confining pressure and frequency for the same number of cycles; (3) ESR damping ratio decreases with increasing shear strain, with a maximum reduction of 50.65%; (4) variations in ESR damping ratio under the influence of freeze–thaw cycles, confining pressure, and frequency are significant; and (5) ESR damping ratio is optimal when FT=12 and RC=10%, and is 29.76% higher than that of plain expansive soil.