# Angular grain fragmentation with DEM modeling: application to fault gouge shearing

## TL;DR

This paper introduces a new simulation method to study how rocks in fault zones break apart and behave under shear stress.

## Contribution

The study introduces a 2D-DEM framework using angular, breakable grains to simulate fault gouge fragmentation more realistically.

## Key findings

- The model captures strain localization and grain rounding during shearing.
- Simulations reproduce the onset and progression of fragmentation and its impact on fault strength.
- The model was validated through comparison with laboratory experiments.

## Abstract

Understanding grain fragmentation in fault gouge is essential for capturing the mechanical behavior and evolution of fault zones under shear. In this study, we present a 2D Discrete Element Method (2D-DEM) framework that simulates comminution using angular, breakable grains, overcoming limitations of traditional models based on spherical particles. Our approach incorporates realistic fracture mechanics and grain geometries to better represent microstructural evolution during shearing. A series of numerical experiments, including Brazilian, oedometric, and shear tests, were conducted to calibrate the model and examine the roles of grain strength, friction, and Young’s modulus. The simulations reproduce key numerical observations such as strain localization, force chain evolution, and grain rounding through chipping mechanisms. Results show that the model captures the onset and progression of fragmentation, as well as its impact on fault strength and mechanical stability. A comparison with a dedicated laboratory experiment is provided. This work provides a robust numerical tool for studying fault gouge behavior and lays the foundation for future studies exploring the influence of initial grain size and material properties on fault mechanics.

A robust numerical tool with fragmentation for studying fault gouge behavior

A robust numerical tool with fragmentation for studying fault gouge behavior

The online version contains supplementary material available at 10.1007/s10035-025-01578-9.