Strain localization in dry sheared granular materials: A compactivity-based approach

Xiao Ma and Ahmed Elbanna
Phys. Rev. E 98, 022906 – Published 28 August 2018

Abstract

Shear banding is widely observed in natural fault zones as well as in laboratory experiments on granular materials. Understanding the dynamics of strain localization under different loading conditions is essential for quantifying strength evolution of fault gouge and energy partitioning during earthquakes and characterizing rheological transitions and fault zone structure changes. To that end, we develop a physics-based continuum model for strain localization in sheared granular materials. The grain-scale dynamics is described by the shear transformation zone (STZ) theory, a nonequilibrium statistical thermodynamic framework for viscoplastic deformation in amorphous materials. Using a finite strain computational framework, we investigate the initiation and growth of complex shear bands under a variety of loading conditions and identify implications for strength evolution and the ductile to brittle transition. Our numerical results show similar localization patterns to field and laboratory observations and suggest that shear zones show more ductile response at higher confining pressures, lower dilatancy, and loose initial conditions. Lower pressures, higher dilatancy, and dense initial conditions favor a brittle response and larger strength drops. These findings shed light on a range of mechanisms for strength evolution in dry sheared granular materials and provide a critical input to physics-based multiscale models of fault zone instabilities.

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  • Received 21 March 2018

DOI:https://doi.org/10.1103/PhysRevE.98.022906

©2018 American Physical Society

Physics Subject Headings (PhySH)

  1. Research Areas
  1. Physical Systems
Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Xiao Ma* and Ahmed Elbanna

  • Department of Civil and Environmental Engineering, University of Illinois, Urbana-Champaign, Illinois, USA

  • *xiaoma5@illinois.edu

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Issue

Vol. 98, Iss. 2 — August 2018

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