| Knowledge of dynamic soil properties, especially dynamic shear modulus and damping ratio, is essential to analyze the response of soil to dynamic loading. Problems in civil engineering practice that require the knowledge of soil properties subjected to dynamic loadings include response of machine foundations subjected to cyclic loading, soil-structure interaction during earthquakes, the operation of machinery, bomb blasts, construction operations, mining, traffic, and wave actions. Adequate information on shear modulus, shear modulus reduction with shear strain amplitude, damping ratio, and its amplification with strain level is required.; Three general approaches typically are used to evaluate these dynamic soil properties. They are laboratory tests, field tests, and empirical correlations. With the increasing development of laboratory and field test techniques, more accurate empirical correlations are possible.; In this research. all available data in the literature were compiled and reanalyzed to find updated empirical equations for shear modulus and damping ratio of plastic and nonplastic soils. Evaluation of various factors that influence the shear modulus and damping ratio of soils also were included in this study, since the dynamic soil properties depend on many factors. The two most influential factors are effective mean principal stress and plasticity index of the soil. Based on these two parameters and strain amplitude, new empirical equations for shear modulus reduction curves and their relationships with damping ratios are proposed.; If the low-amplitude shear modulus (G{dollar}rmsb{lcub}max{rcub}){dollar} for a soil mass is given, shear modulus and damping changes with strain amplitude of the soil are readily calculated. Proposed equations and empirical correlations dependent on the most significant factors provide the user with a practical method to determine the dynamic properties for various types of soils. |
