Correlations of permanent strain and damping coefficients with resilient modulus for coarse-grained subgrade soils

In addition to the resilient modulus (M-R), the permanent deformation and damping characteristic of subgrade soils also need to be studied to properly understand the subgrade soil behaviour under dynamic traffic loading. Soils having relatively high resilient modulus may or may not have small permanent strains (epsilon(p)) and lower damping (xi) Therefore, it is necessary to study resilient modulus with both permanent strain and damping characteristics of subgrade soils. In this study, resilient modulus, permanent strain and damping of subgrade soils were measured under different repeated deviatoric loads and confining pressures. Statistical models were developed to correlate resilient modulus (k(1), k(2), k(3)), permanent strain (alpha(1), alpha(2), alpha(3), alpha(4)) and damping model parameters (beta(1), beta(2), beta(3)) with soil index properties. Models were also developed to correlate epsilon(p) and xi with subgrade soils M-R. Results showed that both permanent strain and damping decreases if resilient modulus increases for South Carolina coarse-grained soils.