Effect of rolling on dissipation in fault gouge

TL;DR

This paper investigates how grain rotation, specifically rolling versus sliding, affects energy dissipation and strength in granular materials under shear, revealing insights into earthquake heat flow paradox.

Contribution

It introduces a numerical approach to quantify rolling and sliding in granular media and links grain rotation patterns to energy dissipation and fault behavior.

Findings

Rolling reduces energy dissipation compared to sliding.

Formation of vorticity cells influences heat flow in fault zones.

Grain rotation patterns may explain earthquake heat flow paradox.

Abstract

Sliding and rolling are two outstanding deformation modes in granular media. The first one induces frictional dissipation whereas the latter one involves deformation with negligible resistance. Using numerical simulations on two-dimensional shear cells, we investigate the effect of the grain rotation on the energy dissipation and the strength of granular materials under quasistatic shear deformation. Rolling and sliding are quantified in terms of the so-called Cosserat rotations. The observed spontaneous formation of vorticity cells and clusters of rotating bearings may provide an explanation for the long standing heat flow paradox of earthquake dynamics.