Unified dynamic shear moduli and damping ratios of sand and clay

Abstract

Available experimental data on dynamic shear moduli and damping ratios of various soils including non-plastic sands to highly plastic clays are collected. Those are reanalyzed and brought into simple unified formulas. The unified formulas express the dynamic shear moduli and the damping ratios in terms of maximum dynamic shear modulus, cyclic shear strain amplitude, mean effective confining pressure and soil's plasticity index. Although the availability of experimental data on clay is still limited at this time, the formulas fit those data reasonably well and could be conveniently utilized in dynamic analyses such as seismic ground response and soil-structure interaction problems.