Small-Strain Shear Modulus of Coral Sand with Various Particle Size Distribution Curves

Particle size distribution plays an important role in the small-strain shear modulus G0 of granular soils. Numerous expressions were proposed for predicting the G0 of siliceous sands in the literature. There are significant differences between the mechanic characteristics of coral sand and siliceous sand. In this paper, a series of resonant column tests were conducted on the coral sand with various particle size distribution curves. The influences of uniformity coefficient Cu, mean-grain size d50, and fines content Fc on G0 of coral sand are investigated. For the given void ratio and confining stress, the G0 of coral sand is smaller than that of siliceous sand. The G0 of coral sand decreases with the increase of Cu, increases with the increase of d50, and first decreases then increases with the increase of Fc. The minimum void ratio emin, instead of the Cu, d50, and Fc, is adopted as a unified index for capturing the characteristics of the particle size distribution of granular soils. The relationships between the parameters in Hardin’s equation and emin are established and a minimum void ratio-based G0 expression for coral sand is proposed. The validity of the new expression for the other types of granular soils is confirmed using the G0 data in the literature.