Failure processes of cemented granular materials

TL;DR

This paper uses a discrete element model to simulate and analyze the failure processes of cemented granular materials, linking microscopic interactions to macroscopic failure modes like shear-banding and ductile failure.

Contribution

It introduces a DEM simulation with realistic bond-breaking criteria that reproduces various experimental failure behaviors of cohesive granular media.

Findings

Reproduces experimental failure modes including shear-banding and ductile failure

Shows the influence of initial volume fraction on failure behavior

Provides a unified framework for porous material failure analysis

Abstract

The mechanics of cohesive or cemented granular materials is complex, combining the heterogeneous responses of granular media, like force chains, with clearly defined material properties. Here, we use a discrete element model (DEM) simulation, consisting of an assemblage of elastic particles connected by softer but breakable elastic bonds, to explore how this class of material deforms and fails under uniaxial compression. We are particularly interested in the connection between the microscopic interactions among the grains or particles and the macroscopic material response. To this end, the properties of the particles and the stiffness of the bonds are matched to experimental measurements of a cohesive granular media with tunable elasticity. The criterion for breaking a bond is also based on an explicit Griffith energy balance, with realistic surface energies. By varying the initial volume fraction of the particle assembles we show that this simple model reproduces a wide range of experimental behaviors, both in the elastic limit and beyond it. These include quantitative details of the distinct failure modes of shear-banding, ductile failure and compaction banding or anti-cracks, as well as the transitions between these modes. The present work, therefore, provides a unified framework for understanding the failure of porous materials such as sandstone, marble, powder aggregates, snow and foam.