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Laboratory Studies of Granular Materials Under Shear: From Avalanches to Force Chains


Marteau, Eloïse Sophie Hélène (2018) Laboratory Studies of Granular Materials Under Shear: From Avalanches to Force Chains. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/FKM0-P754.


Granular materials reveal their complexity and some of their unique features when subjected to shear deformation. They can dilate, behave like a solid or a fluid, and are known to carry external forces preferentially as force chains. In this dissertation, we employ laboratory experiments to study the complex behavior of granular materials under shear. We introduce a multiscale approach in which the underlying grain-scale mechanics are experimentally measured and homogenized to obtain enriched macroscopic quantities. First, we investigate granular avalanches spontaneously generated by a rotating drum. Measurements of grain kinematics are directly incorporated into a rate-dependent plasticity model that explains and reproduces the life cycle of laboratory avalanches. The results presented here feature dilatancy as the key material parameter governing the triggering of an avalanche. Second, we report a set of experiments performed on a custom-built mechanical device that allows a specimen composed of a two-dimensional analogue granular assembly to be subjected to quasi-static shear conditions. A numerical force inference technique, the Granular Element Method (GEM), provides direct observation and quantitative characterization of force chain structures in assemblies made of realistic grains. Equipped with a complete description of the grain-scale mechanics, we show that shear deformation creates geometrical (fabric) and mechanical (force) anisotropy. Finally, the influence of grain shape on grain-scale processes is studied. We find that grain interlocking is a prominent deformation mechanism for non-circular grains that ultimately promotes a significant increase in macroscopic shear strength. By seamlessly connecting grain-scale information to continuum scale experiments, this dissertation sheds light on the multiscale mechanical behavior of granular assemblies under shear.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Granular materials, geomechanics, laboratory experiments, multiscale modeling
Degree Grantor:California Institute of Technology
Division:Engineering and Applied Science
Major Option:Applied Mechanics
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Andrade, Jose E.
Thesis Committee:
  • Ravichandran, Guruswami (chair)
  • Asimaki, Domniki
  • Bhattacharya, Kaushik
  • Andrade, Jose E.
Defense Date:25 October 2017
Record Number:CaltechTHESIS:05142018-133453405
Persistent URL:
Related URLs:
URLURL TypeDescription adapted for Ch. 2. adapted for Ch. 3. adapted for Ch. 4.
Marteau, Eloïse Sophie Hélène0000-0001-7696-6264
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:10879
Deposited By: Eloise Marteau
Deposited On:24 May 2018 23:14
Last Modified:28 Oct 2021 22:49

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