Creep of granular ice with and without dispersed particles

Song, Min; Cole, David M.; Baker, Ian

doi:10.3189/172756505781829377

Cited by 20 publications

(20 citation statements)

References 39 publications

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“…Contradictory data have been obtained even for similar conditions, and divergent or novel claims make the topic controversial. Some convincing laboratory experiments indicate that n ≈ 3 applies to all stresses in the range 0.5− 1.5 × 10 5 Pa (Russell-Head and Budd, 1979), whereas other such experiments suggest that n ≈ 2 (Jacka 1984), or that 1 ≤ n ≤ 2 (Song et al, 2005;Colbeck and Evans, 1973;Goldsby and Kohlstedt, 2001). Several fi eld analyses of tilting boreholes and ice cap morphology and fl ow indicate that the effective value for n is between 2.5 and 4 (Raymond, 1973(Raymond, , 1980Reeh et al, 1985;Reeh and Paterson, 1988;Martin and Sanderson, 1980;Thomas et al, 1980;Cuffey, 2006).…”

Section: Introductionmentioning

confidence: 94%

How nonlinear is the creep deformation of polar ice? A new field assessment

Cuffey

Kavanaugh

2011

Geology

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Most analyses of glacial systems require a relationship between strain rates and stresses for ice deforming in creep. For conditions relevant to glacier fl ow, much evidence shows that strain rates increase approximately as deviatoric stress raised to a power n. Field and laboratory experiments suggest that n ≈ ≈ 3, but values span a wide range and controversy persists. Most fi eld efforts to determine n seek clarity by examining situations with simple stress states. We instead use a fully three-dimensional model to interpret measurements of fl ow of an Antarctic outlet glacier that follows a tortuous path through a mountain range. By comparing observed fl ow to models with different parameter values, we conclude that the effective n must be between 2.6 and 5.1 (99% confi dence). The best match occurs with n ≈ ≈ 3.5. We conclude that use of the traditional value is appropriate for polar ice deforming at stresses of 0.6-1.2 × 10 5 Pa.on June 5, 2015 geology.gsapubs.org Downloaded from

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Section: Introductionmentioning

confidence: 94%

How nonlinear is the creep deformation of polar ice? A new field assessment

Cuffey

Kavanaugh

2011

Geology

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“…However, the fact that similar behavior has been documented in later experiments (as discussed above) suggests that it could reflect a real phenomenon. Further evidence supporting this has been provided by Baker and Gerberich [], Yasui and Arakawa [], and Song et al [], among others. On the other hand, creep experiments conducted by Jacka et al [] failed to show any systematic change in creep rate as debris concentration was varied from 0 to 14.5% by volume at −12°C and 130 kPa.…”

Section: Experimental Constraintsmentioning

confidence: 99%

“…An intriguing group of experiments that may shed some light on the puzzle was recently published by Song and colleagues [ Song et al ., , , ]. Using a unique creep apparatus, the authors investigated the micromechanical behavior of pure fine‐grained ice and ice containing 1–4% silt‐sized particles.…”

Section: Experimental Constraintsmentioning

confidence: 99%

“…An important observation in one set of experiments was that dislocation density was systematically larger in dirty ice than clean. Since macroscopic creep by dislocation glide is a function of both the velocity and density of dislocations, increased dislocation density facilitates faster creep in the dirty ice [ Song et al, ]. In a separate cyclic creep study, these authors were able to isolate the contributions to strain by dislocation glide and grain‐boundary sliding as temperature, applied stress, and debris concentration were varied.…”

Section: Experimental Constraintsmentioning

confidence: 99%

“…Dispersed particles may have additional effects on shear resistance by influencing dislocation density and ice grain size. As discussed earlier, there is some experimental evidence that particles can act as net dislocation sources, thereby increasing the dislocation density compared with particle‐free ice [ Song et al, ]. Since the macroscopic creep rate is proportional to ρ d bv where ρ d is dislocation density and v is dislocation velocity, an increase in dislocation density results in a proportional increase in creep rate if the mobility of dislocations is not affected independently.…”

Section: Theoretical Approachesmentioning

confidence: 99%

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Deformation of debris-ice mixtures

2014

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Mixtures of rock debris and ice are common in high-latitude and high-altitude environments and are thought to be widespread elsewhere in our solar system. In the form of permafrost soils, glaciers, and rock glaciers, these debris-ice mixtures are often not static but slide and creep, generating many of the landforms and landscapes associated with the cryosphere. In this review, a broad range of field observations, theory, and experimental work relevant to the mechanical interactions between ice and rock debris are evaluated, with emphasis on the temperature and stress regimes common in terrestrial surface and near-surface environments. The first-order variables governing the deformation of debris-ice mixtures in these environments are debris concentration, particle size, temperature, solute concentration (salinity), and stress. A key observation from prior studies, consistent with expectations, is that debris-ice mixtures are usually more resistant to deformation at low temperatures than their pure end-member components. However, at temperatures closer to melting, the growth of unfrozen water films at ice-particle interfaces begins to reduce the strengthening effect and can even lead to profound weakening. Using existing quantitative relationships from theoretical and experimental work in permafrost engineering, ice mechanics, and glaciology combined with theory adapted from metallurgy and materials science, a simple constitutive framework is assembled that is capable of capturing most of the observed dynamics. This framework highlights the competition between the role of debris in impeding ice creep and the mitigating effects of unfrozen water at debris-ice interfaces.

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The Effects of H₂SO₄ on the Mechanical Behavior and Microstructural Evolution of Polycrystalline Ice

Hammonds

Baker

2018

JGR Earth Surface

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The Earth's large continental ice sheets contain a variety of naturally occurring impurities, both soluble and insoluble. Understanding how these impurities affect the rheology, intrinsic thermodynamic properties, and fate of these ice sheets is not well understood. To investigate the effects that trace amounts of H2SO4 have on the flow and ductility of polycrystalline ice, a series of mechanical tests were conducted at −6, −10, −12.5, and −20°C using laboratory‐prepared specimens of polycrystalline ice doped with 1–15 ppm of H2SO4. Parallel tests were performed on identical but undoped specimens of polycrystalline ice. Mechanical testing included constant‐load tensile creep tests at an initial stress of 0.75 MPa and compression tests at constant displacement rates with initial strain rates ranging from 1 × 10−6 to 1 × 10−4 s−1. It was found that H2SO4‐doped specimens of ice exhibited faster creep rates in tension and significantly lower peak stresses in compression, when compared to the undoped ice. Postmortem microstructural analyses were performed using cross‐polarized light thin section imaging, X‐ray computed microtomography, Raman spectroscopy, and electron backscatter diffraction. These analyses showed that H2SO4‐doped specimens had a larger grain size at strains ≤15%, and an earlier onset of microcracking at lower strain rates than the undoped ice. Strain‐induced grain boundary migration was found to be the predominant mechanism of recrystallization in both doped and undoped specimens. Further, an aqueous phase of H2SO4 was found to exist at the grain boundaries and triple junctions of the doped ice, which is thought to have significantly contributed toward its reduced viscosity.

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Creep of granular ice with and without dispersed particles

Cited by 20 publications

References 39 publications

How nonlinear is the creep deformation of polar ice? A new field assessment

How nonlinear is the creep deformation of polar ice? A new field assessment

Deformation of debris-ice mixtures

The Effects of H₂SO₄ on the Mechanical Behavior and Microstructural Evolution of Polycrystalline Ice

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Creep of granular ice with and without dispersed particles

Cited by 20 publications

References 39 publications

How nonlinear is the creep deformation of polar ice? A new field assessment

How nonlinear is the creep deformation of polar ice? A new field assessment

Deformation of debris-ice mixtures

The Effects of H2SO4 on the Mechanical Behavior and Microstructural Evolution of Polycrystalline Ice

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Product

Resources

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The Effects of H₂SO₄ on the Mechanical Behavior and Microstructural Evolution of Polycrystalline Ice