Modified Models for Predicting Dynamic Properties of Granular Soil Under Anisotropic Consolidation

The shear modulus and damping ratio are important parameters for the design of structures subjected to dynamic loading and can be obtained by in situ and laboratory measurements. Previous research has lacked quantitative study of the effects of anisotropic consolidation, especially in extension mode, on the dynamic properties of granular soil. The objective of the current study was to evaluate the dynamic properties of sand-gravel mixtures for practical applications. To this end, resonant column, cyclic triaxial, and S-wave velocity measurements under anisotropic confining conditions were conducted. The influence of mean effective consolidation stress, consolidation stress ratio under constant and variable mean effective stresses, and gravel content on the maximum shear modulus $G_{\max }$, $G/G_{\max }\text{-}\gamma$ and $D\text{-}\gamma$ curves are discussed. Simple formulations are presented to predict $G_{\max }$ and the reference strain (${\gamma }_r$) of sand-gravel mixtures using parameters that are easy to obtain from test data. A modified empirical model is proposed based on the test results to estimate the shear modulus degradation and damping ratio. The modified model is validated using experimental data from previous studies. The results indicate that the proposed empirical model is capable of evaluating the shear modulus and damping ratio of granular soil.