Discrete element modeling of subglacial sediment deformation

Anders Damsgaard, David L. Egholm, Jan A. Piotrowski, Slawek Tulaczyk, Nicolaj Krog Larsen, Karol Tylmann

Research output: Contribution to journal/Conference contribution in journal/Contribution to newspaperJournal articleResearchpeer-review

Abstract

The Discrete Element Method (DEM) is used in this study to explore the highly nonlinear dynamics of a granular bed when exposed to stress conditions comparable to those at the bed of warm-based glaciers. Complementary to analog experiments, the numerical approach allows a detailed analysis of the material dynamics and the shear zone development during progressive shear strain. The geometry of the heterogeneous stress network is visible in the form of force-carrying grain bridges and adjacent, volumetrically dominant, inactive zones. We demonstrate how the shear zone thickness and dilation depends on the level of normal (overburden) stress, and we show how high normal stress can mobilize material to great depths. The particle rotational axes tend to align with progressive shear strain, with rotations both along and reverse to the shear direction. The results from successive laboratory ring-shear experiments on simple granular materials are compared to results from similar numerical experiments. The simulated DEM material and all tested laboratory materials deform by an elasto-plastic rheology under the applied effective normal stress. These results demonstrate that the DEM is a viable alternative to continuum models for small-scale analysis of sediment deformation. It can be used to simulate the macromechanical behavior of simple granular sediments, and it provides an opportunity to study how microstructures in subglacial sediments are formed during progressive shear strain.
Original languageEnglish
JournalJournal of Geophysical Research: Earth Surface
Volume118
Pages (from-to)2230-2242
Number of pages13
ISSN2169-9003
DOIs
Publication statusPublished - 2013

Fingerprint

Dive into the research topics of 'Discrete element modeling of subglacial sediment deformation'. Together they form a unique fingerprint.

Cite this