Effect of Gradation and Particle Shape on Small-Strain Young's Modulus and Poisson's Ratio of Sands

The influence of gradation and particle shape on the small-strain Young's modulus of dry sands is investigated through a comprehensive set of resonant column tests in the flexural mode of vibration. Experiments are performed on an array of sands with different coefficients of uniformity and particle shapes. The effect of gradation is investigated using tests on sands with similar particle shapes. The effect of particle shape is then examined through the experimental results on sands with a range of particle shapes. A new model is developed to incorporate the effects of gradation and particle shape into the prediction of the small-strain Young's modulus. The proposed model is verified and compared with the existing models in the literature using the state parameter in the critical state soil mechanics framework. It is shown that the proposed model outperforms the previous ones considering the significant effect of particle shape on the small-strain Young's modulus. Using the theory of elasticity, a model is developed for the prediction of Poisson's ratio for sands taking into account the effects of particle shape and gradation. (C) 2016 American Society of Civil Engineers.