Dynamic properties of frozen rubber-reinforced expansive soils under confining pressure

In recent years, waste rubber has been increasingly utilized to enhance the performance of expansive soil foundations. This study aims to investigate the influence of rubber powder on the dynamic characteristics of frozen rubber-reinforced expansive soils (RRES) in permafrost regions. Temperature-controlled dynamic triaxial tests were conducted on RRES samples, varying rubber content, freezing temperatures, and confining pressures. The key findings are as follows: (1) A modified Hardin model with freezing temperature and rubber content as correction factors was established, which was verified to be useful for describing the dynamic stress-strain relationship. (2) Under the confining pressure, the dynamic shear modulus decreases with increasing rubber content. When the rubber content changes from 5% to 10%, the dynamic shear modulus decreases by about 20 MPa; the change becomes less obvious after the content exceeds 20%, and the RRES tends to show the characteristics of rubber. (3) As the rubber content increases, the damping ratio rises and shows the phenomenon of increasing and then decreasing with increasing confining pressure, and reaching a maximum at 0.4 MPa. (4) A prediction model for the maximum dynamic shear modulus with rubber content, freezing temperature and confining pressure is proposed.