A Gradation-Dependent Particle Shape Factor For Characterizing Small-Strain Shear Modulus Of Sand-Gravel Mixtures

In this study, a series of shear wave velocity tests were conducted on two types of sand-gravel mixtures with a wide range of particle size distributions. The effect of the particle shape on the small-strain shear modulus (G(max)) was investigated using a customized, large-scale triaxial apparatus. The results showed that G(max) increases with the decrease in particle roundness when the uniformity coefficient (C-u) is less than a certain value. However, this increasing trend gradually flattens with the further increase of C-u . Thus, the effect of particle shape on the G max varies with the particle gradation. The performances of six relationships proposed in the literature for predicting G(max) were compared and evaluated in terms of their predictive capabilities. An empirical G(max) model based on the Hardin and Black equation was proposed by including a Fourier-based shape factor modified by C-u . The model can characterize the difference in the variation of G(max) with C-u due to different particle shapes and was thereafter validated. Furthermore, the model serves as a reference guide for estimating the G(max )of soils with various particle size distributions through their particle characteristics.