Strength and energy consumption of inherently anisotropic rocks at failure

TL;DR

This study models inherently anisotropic rocks using a discrete-element approach, revealing how failure strength, failure modes, and energy consumption vary with anisotropy level and loading orientation.

Contribution

It introduces a novel simulation method to analyze the effects of anisotropy and loading orientation on rock failure and energy consumption.

Findings

Failure strength increases when load is orthogonal to layers.

Failure modes evolve with loading orientation.

Bond length controls energy consumption during fissuring.

Abstract

Using a discrete-element approach and a bonding interaction law, we model and test crushable inherently anisotropic structures reminiscent of the layering found in sedimentary and metamorphic rocks. By systematically modifying the level of inherent anisotropy, we characterize the evolution of the failure strength of circular rock samples discretized using a modified Voronoi tesselation under diametral point loading at different orientations relative to the sample's layers. We characterize the failure strength, which can dramatically increase as the loading becomes orthogonal to the rock layers. We also describe the evolution of the macroscopic failure modes as a function of the loading orientation and the energy consumption at fissuring. Our simulation strategy let us conclude that the length of bonds between Voronoi cells controls the energy being consumed in fissuring the rock sample, although failure modes and strength are considerably changing. We end up this work showing that the microstructure is largely afected by the level of inherent anisotropy and loading orientation.