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The tertiary creep of polycrystalline ice: experimental evidence for stress-dependent levels of strain-rate enhancement

journal contribution
posted on 2023-05-17, 12:29 authored by Adam TreverrowAdam Treverrow, Budd, WF, Jacka, TH, Roland WarnerRoland Warner
Laboratory creep deformation experiments have been conducted on initially isotropic laboratory-made samples of polycrystalline ice. Steady-state tertiary creep rates, ·ter, were determined at strains exceeding 10% in either uniaxial-compression or simple-shear experiments. Isotropic minimum strain rates, ·min, determined at ∼1% strain, provide a reference for comparing the relative magnitude of tertiary creep rates in shear and compression through the use of strain-rate enhancement factors, E, defined as the ratio of corresponding tertiary and isotropic minimum creep rates, i.e. E = ·ter/·min. The magnitude of strain-rate enhancement in simple shear was found to exceed that in uniaxial compression by a constant factor of 2.3. Results of experiments conducted at octahedral shear stresses of τo = 0.04–0.80 MPa indicate a creep power-law stress exponent of n = 3 for isotropic minimum creep rates and n = 3.5 for tertiary creep rates. The difference in stress exponents for minimum and tertiary creep regimes can be interpreted as a τo stress-dependent level of strain-rate enhancement, i.e. E α τ1/2o .  The implications of these results for deformation in complex multicomponent stress configurations and at stresses below those used in the current experiments are discussed.

History

Publication title

Journal of Glaciology

Volume

58

Issue

208

Pagination

301-314

ISSN

0022-1430

Department/School

Institute for Marine and Antarctic Studies

Publisher

International Glaciological Society

Place of publication

Cambridge, United Kingdom

Rights statement

Copyright 2012 International Glaciological Society

Repository Status

  • Restricted

Socio-economic Objectives

Expanding knowledge in the earth sciences

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