Moduli and Damping Factors for Dynamic Analyses of Cohesionless Soils

Concepts

Geotechnical EngineeringShear StrainSoil DynamicsEngineeringDamping FactorsGeotechnical PropertyMechanicsSoil MechanicsSoil-structure InteractionCivil EngineeringMechanical EngineeringGeomechanicsDamping RatiosSoil StructureCohesionless SoilSoil PropertiesUnsaturated Soil MechanicsSoil Mechanic

TL;DR

Laboratory and field tests provide data on the shear modulus and damping ratios of sands and gravelly soils. The study proposes a simple relationship linking the shear modulus of cohesionless soils to a modulus stiffness coefficient and effective mean principal stress, and offers guidance on how to vary shear modulus with strain and damping ratios. The authors suggest low‑strain modulus coefficient values, show they can be estimated from standard penetration resistance for sands, and outline how to determine shear modulus variation with strain and damping ratios for sandy and gravelly soils. Estimated modulus coefficients for sands can be derived from penetration resistance, while gravel values are 1.35–2.5 times higher than those for sands.

Abstract

Data are presented concerning the shear modulus and damping ratios of sands and gravelly soils as determined by laboratory and field tests. A simple relationship is proposed to relate the shear modulus of a cohesionless soil to a modulus stiffness coefficient, which is a soil property and depends on the characteristics of the soil, and the effective mean principal stress at any point in the soil. Values for the modulus coefficient at low strains are suggested, and it is shown that these values for sands can be estimated from the standard penetration resistance of the sand. Values for gravels are generally greater than those for sands by factors ranging from 1.35–2.5. Suggestions are also made for determining the variation of shear modulus with shear strain and the damping ratios for both sandy and gravelly soils.