Shakedown of unbound granular material

TL;DR

This paper investigates the elasto-plastic response of unbound granular materials under cyclic loading to determine if a limit load exists below which the material stabilizes without further deformation.

Contribution

It provides a detailed simulation study of unbound granular materials' behavior under cyclic loading, focusing on the existence of a shake-down limit load.

Findings

Identification of response regimes based on dissipated energy

Evidence suggesting a threshold load for shake-down behavior

Insights into the deformation accumulation in granular materials

Abstract

Compacted unbound granular materials are extensively used as sub-layer in pavement design. Most pavement design guides assume that they are responsible for the degradation and deformation of the roads and railways that they support. Biaxial tests are usually employed to investigate the elasto-plastic response of these materials to cyclic loading. A particularly interesting question is whether a limit load exists, below which the excitations shake down, in the sense that the material does not accumulate further deformations. We have carried out a detailed study of the elasto-plastic behavior of a simple model of unbound granular matter submitted to cyclic loading. The dissipated energy through out the simulation has been used for the characterization of the different regimes of responses.