Numerical Investigation on the Compressive Behavior of Hierarchical Granular Piles

TL;DR

This study uses large-scale numerical simulations to validate the multi-stage compression process of hierarchical granular piles, revealing insights into their structural evolution relevant to geoscience and planetary science.

Contribution

The paper provides the first numerical validation of the three-stage evolution in hierarchical granular piles and introduces a semi-analytical model for their compression behavior.

Findings

Confirmed three-stage compression process: rearrangement, plastic deformation, elastic deformation.

Developed a semi-analytical model for the compression curve.

Insights into internal structure evolution of icy planetary bodies.

Abstract

Hierarchical granular piles composed of aggregates are key structural features in both geoscience and planetary science, from fault gouge in seismic zones to the internal structures of comets. Although experimental studies have suggested a multi-step evolution in their packing structure, this hypothesis has lacked numerical validation. In this study, we performed large-scale numerical simulations using the discrete element method to investigate the compressive behavior of hierarchical granular piles. We successfully reproduced and confirmed a three-stage evolution process: (i) rearrangement of the aggregate packing structure, (ii) plastic deformation of small aggregates, and (iii) elastic deformation of constituent particles. Additionally, we developed a semi-analytical model for the compression curve, offering insights into the compressive stages and structural dynamics. Our findings have applications in modeling the internal density profiles of comets and in understanding the early thermal evolution of small icy bodies.