Relationships between Particle Shape Characteristics and Macroscopic Damping in Dry Sands

Abstract

The objective of this study is to investigate the relationships between the scalar particle shape descriptors and macroscopic dissipative properties of dry, clean sands. To define these relationships in a consistent and useful manner, it is important to identify and examine the relevant microscopic particulate shape characteristics and their effects upon the macroscopic strain-dependent damping ratio curves, ξ(γ), as measured by resonant column procedures. The scalar particle shape descriptors are examined to determine the appropriate representative definitions for each of the three scales of particle shape (roughness, roundness, and sphericity). Quantitative mineralogy scanning technology and image analysis procedures are used to quantify these representative particulate descriptors and the specific surface for a significantly larger number of standardized sand samples’ constituent particles than previously examined. Particle descriptor data are projected to represent each of the standardized sands and then related to the shifts in small-strain ξ(γ). From this study, it was found that the roundness and roughness were more influential shape scales than the sphericity, and three representative scalar particulate descriptors (specific surface, Hayakawa and Oguchi roundness, and solidity) display strong linear relationships with respect to the measures of the slopes of each sand’s ξ(γ).