Abstract: In order to study the dynamic characteristics of feldspar sandstone rockfill materials in earth-rock dam project, we tested the dynamic modulus and damping ratio of feldspar sandstone rockfill materials of a face rockfill dam using large multi-function static dynamic triaxial apparatus. Through the test we obtained the influence of confining pressure on the maximum dynamic modulus, dynamic shear modulus ratio and damping ratio, and further determined the dynamic modulus and damping ratio of three kinds of rockfill materials, namely, main rockfill, transition material and cushion layer based on Hardin-Drnevich model. Results elucidated that the dynamic modulus declined gradually with the increase of dynamic strain; the maximum dynamic modulus increased with the rising of confining pressure; the dynamic shear modulus ratio of the three materials shrank with the increase of dynamic shear strain, and such shrinkage attenuated with the rising of effective consolidating confining pressure, which is consistent with the Hardin-Drnevich formula. The damping ratio augmented with the increase of dynamic shear strain, but reduced with the rising of confining pressure, which can also be described by the modified Hardin-Drnevich formula suggested in the paper. The research findings offer theoretical basis for seismic design and dynamic stability evaluation of earth-rock dams.

Key words: feldspar sandstone rockfill material, static and dynamic triaxial test, dynamic modulus, damping ratio, confining pressure, Hardin-Drnevich model