Gelifluction and Thixotropy of Maritime Antarctic Soils: Small-Scale Measurements with a Rotational Rheometer

Benhua Sun, Paul G. Dennis, Kevin K. Newsham, David W. Hopkins, Paul D. Hallett*

*Corresponding author for this work

Research output: Contribution to journalArticle

Abstract

Gelifluction, thixotropy and yield stress were measured from <5 g soil samples taken from Signy, Alectoria, Greenwich, Wiencke and Livingston islands in the maritime Antarctic using a temperature-controlled rotational rheometer. The small sample size that this method permitted is compatible with sampling from sensitive sample locations. An oscillating 10 Pa shear stress was applied to samples at -0.5 kPa water potential. Two freeze-thaw cycles had temperature ramps from 5°C to -10°C over 2 h, followed by -10°C to 5°C over 2 h and finally at 5°C for 1 h. At freezing onset, the shear modulus, G, dropped to 4-50 per cent of thawed G, with no differences between locations. At thawing onset, G dropped to 8-32 per cent of thawed G, with significant differences between locations (P <0.001). Thixotropy was then measured by applying a 2 kPa oscillating shear stress for 10 min, followed by relaxation at 10 Pa for 2 h. The increased shear stress caused G to drop to less than 8 per cent of the pre-stressed value, with no difference between locations. After 0.1 and 2 h, G was 18-65 per cent and 31-82 per cent of the pre-stressed value, respectively. A shear ramp determined yield stresses ranging from 494-2217 Pa. These findings demonstrate the potential risk of more frequent freeze-thaw cycles or the occurrence of thawed soil to the stability of polar soils. Gelifluction through more frequent freeze-thaw cycles could result in increased slope movement, whereas thixotropy caused by trampling of thawed soils could exacerbate mechanical damage of surface soils.

Original languageEnglish
Pages (from-to)314–321
Number of pages8
JournalPermafrost and Periglacial Processes
Volume28
Issue number1
Early online date2 Feb 2016
DOIs
Publication statusPublished - 1 Jan 2017

Keywords

  • Gelifluction
  • Maritime Antarctic
  • Rotational rheometer
  • Soil
  • Thixotropy
  • Yield stress

ASJC Scopus subject areas

  • Earth-Surface Processes

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