Compaction of Granular Columns under Thermal Cycling

TL;DR

This study explores how thermal cycling causes granular materials to compact through differential expansion, revealing slow relaxation and aging behaviors similar to glassy systems, with implications for geology and engineering.

Contribution

It demonstrates that differential thermal expansion drives granular compaction and applies multiple models to quantify the slow relaxation dynamics, advancing understanding of thermal effects on granular materials.

Findings

Granular compaction is driven by differential thermal expansion.

Granular materials exhibit slow relaxation and aging dynamics.

Multiple models effectively fit the compaction data.

Abstract

Granular materials undergo compaction under periodic temperature fluctuations, leading to various engineering and geological phenomena from landslides to silo compaction. Although thermal effects on granular materials have been extensively studied in soil mechanics and geology, the underlying physical mechanisms remain unclear. This study investigates the compaction dynamics of granular materials subjected to thermal cycling using monodisperse glass beads and polydisperse sand packings. We demonstrate that differential thermal expansion between the container and the grains drives compaction through shear in our experimental systems. We quantify compaction dynamics using three established fitting models: Kohlrausch-Williams-Watts (KWW), double-exponential, and logarithmic functions. Our results reveal that granular materials exhibit slow relaxation processes in response to weak perturbations, displaying aging dynamics similar to those observed in glassy systems. These findings provide insights into fundamental mechanisms of granular compaction with broad implications for geological and engineering applications.