Prediction model for small-strain shear modulus of non-plastic fine-coarse-grained soil mixtures based on extreme void ratios

The small-strain shear modulus G0 is a fundamental parameter for characterizing the dynamic behavior of soils. In this study, bender element tests were performed to investigate how the effective confining stress a'c, relative density Dr, void ratio e, and a wide range of fines content FC (0%-100%) influence the G0 of soil mixtures containing both fine and coarse grains. The results show that under the same e and a'c, G0 first decreases and then increases with increasing FC. Furthermore, as characteristic state parameters, the extreme void ratios (i.e., the maximum void ratio emax and the minimum void ratio emin) reflect comprehensively the particle size distribution and shape of fine-coarse-grained soil mixtures. Under the same a'c, the lower limit of G0 (G0min) decreases with increasing emax and the upper limit (G0max) decreases with increasing emin, and the extrapolated upper and lower limits of the normalized G0/(a'c/Pa) show a negative power-law relationship with emin and emax, respectively. Empirical formulas are established for the G0max and G0min of fine-coarse-grained soil mixtures, and G0 under various Dr can be interpolated according to G0min (for Dr = 0) and G0max (for Dr = 1). Finally, a G0 prediction model that offers reasonable characterization of fine-coarse-grained soil mixtures with different FC is established based on emin and emax.