Abstract: The dynamic modulus and damping ratio of sandy gravel material of a sandy gravel dam with asphalt concrete core wall are tested by large dynamic triaxial tester. The dynamic stress-strain characteristics of sandy gravel dam material are studied. The influence of confining pressure on the maximum dynamic modulus, dynamic shear modulus ratio and damping ratio is analyzed. The characteristic parameters such as the dynamic modulus and damping ratio of the dam shell material and transition material are determined using the modified equivalent linear viscoelastic model. Test results show that with the climbing of confining pressure, the dynamic shear modulus of sandy gravel dam material increases while damping ratio decreases. With the growth of dynamic strain, the dynamic shear modulus declines while damping ratio increases. By incorporating normalized dynamic strain into the modified equivalent linear model, the influence of confining pressure on dynamic modulus attenuation and damping ratio are better eliminated, and moreover the dynamic deformation characteristics of sandy gravel dam material are more accurately reflected.

Key words: sandy gravel material, dynamic modulus, damping ratio, dynamic shear modulus ratio, modified equivalent linear model, large-scale dynamic triaxial test