Wave Propagation and Elasticity in Granular Soils: A Numerical Approach for a Micromechanical Perspective

Abstract

In this work we propose an overview of results about propagation of waves and elasticity in soils over the last 30 years. Remarkably, the chapter attempts to frame and compare contributions from soil mechanics, solid mechanics and physics. In a wide landscape, we focus on the micromechanical approach to the topic. Numerical simulations, based on the Discrete Element Method, have revealed the outmost role of the microstructure in characterising the elastic behaviour of granular soils. Following this evidence, microstructure-based continuum models have been developed and are discussed here, starting from the classical Effective Medium Theory. Finally, the chapter describes how micromechanical models can be extended to the case of immersed granular soils, and compares the new model with experiments on sand soils in a wide range of saturation degrees.

X-ray 3D imaging–based microunderstanding of granular mixtures: Stiffness enhancement by adding small fractions of soft particles

“…It involves small perturbations that do not alter the microstructure or cause permanent effects. When the wavelength is significantly longer than the internal scales of granular packings, such as particle or cluster size, the propagation velocity can be defined for the equivalent continuum, where the elastic moduli and mass density refer to the bulk medium ( 10 ). Small-strain stiffness, i.e., elastic stiffness, is a fundamental macroscale mechanical parameter for a wide range of engineering problems, and it is used for the prediction of granular response under both static and dynamic loading conditions ( 11 – 18 ).…”