Abstract: Through the dynamic tests on the CAS-1 lunar soil simulant (national standard sample) which is developed by the Institute of Geochemistry and the National Astronomical Observatories, Chinese Academy of Sciences with the GDS resonant column test instrument, the effect of the different void ratios and the different confining pressures on the dynamic shear modulus G and the damping ratio ? is analyzed. The test results show that, the dynamic shear modulus G is smaller as well as the damping ratio ? is larger, and dynamic shear modulus decreases rapidly as well as damping ratio increases sharply with the increase of shear strain in the real lunar surface environmental conditions with low stress level and large void ratio. By using the Hardin-Drnevich model, the average fitting curve of G/Gmax and ? /? max with the change of the dynamic shear strain ? under different void ratios and different confining pressures are obtained; and the correlation formulas between dynamic parameters of the maximum dynamic shear modulus Gmax, the maximum damping ratio ? max, the reference shear strain ? r and the stress level ? are discussed. Accordingly, the range intervals of Gmax, ? max, ? r within the drill sampling depth (0-3 m) of the lunar soil as well as the recommended values of G/Gmax and ? corresponding to each of the shear strain are presented.

Key words: CAS-1 lunar soil simulant , dynamic shear modulus, damping ratio, dynamic shear modulus ratio, resonant column test, Hardin-Drnevich hyperbolic model