Abstract: The dynamic properties of Hefei expansive soil improved by an optimized content of 7% of phosphorus tailing by product additives were laboratory studied by the GDS dynamic triaxial testing devices under cyclic loading conditions. The improved Hefei expansive soil samples were tested under different loading frequencies and confining pressures so that the dynamic modulus and damping ratios relationship with these potential influence factors could be investigated. The results indicate that, the stress-strain relationship is strongly influenced by the confining pressures. Under different sample confining pressures, the dynamic modulus values varied significantly. Under the same amount of deformation, the higher confining pressure induces a higher dynamic modulus; so does the loading frequency on the dynamic modulus. With the increase of confining pressures and lading frequencies, plastic deformation in the soil samples reduces and elastic deformation increases with the same value of dynamic modulus in the soil sample, Ed.

Key words: expansive soil, phosphorus tailings, dynamic characteristics, dynamic modulus