Resilient behavior of coarse granular materials in three dimensional anisotropic stress state

Abstract

The coarse granular materials in the pavement base and subbase layers are generally in the stress state of three dimensional anisotropy, while most previous experimental researches regarding the base and subbase materials focused on the isotropic or axisymmetric K0 stress conditions. In this study, the resilient characteristics of unbound granular materials in initial three dimensional anisotropic stress states were investigated through an electro-mechanical true triaxial apparatus. The influences of initial shear stress, qini, coefficient of intermediate principal stress, b, amplitude of cyclic major principal stress, σ1ampl, and moisture content on the resilient responses of granular materials were investigated. Test results reveal that the resilient response of unbound granular materials is strongly affected by the three dimensional stress anisotropy in the saturated condition. With the increase of b from 0 to 0.8, a significant reduction of Mr occurs, and this reduction becomes intensified as qini increases. It is also found that Mr is increased by the increase of qini for almost all tests, and the increasing rate varies at different σ1ampl, b and moisture content values. Based on the experimental results, an empirical model to predict resilient modulus is proposed incorporating the effects of initial three dimensional stress anisotropy, which is expected to serve as a basic model to calculate the resilient modulus of granular materials in three dimensional stress state.