University of Sussex
Browse

File(s) not publicly available

An analysis of mechanisms of ice-wedge casting based on geotechnical centrifuge simulations

journal contribution
posted on 2023-06-07, 17:22 authored by Charles Harris, Julian MurtonJulian Murton, Michael C R Davies
Here we interpret the outcomes of scaled geotechnical centrifuge simulation of ice-wedge casting in terms of the likely significance of Quaternary ice-wedge pseudomorphs observed within different host sediments. Six experiments were completed in which 1/30th scale models of an ice-wedge embedded within frozen host sediments beneath a 25 mm thick unfrozen active layer were thawed from the surface downwards in the geotechnical centrifuge under a 30 times gravity (30 g) acceleration. Host sediment granulometry and/or ice contents were varied in each model, with host materials comprising medium sands, fine sandy silts and silty clays. The model ice-wedge was 50 mm at the top, 150 mm deep, and extended across the full width of the 450 mm wide test box. Centrifuge scaling laws indicate that under an acceleration of 30 g, stress distribution was equivalent to a 13.5 m long section of a 4.5 m high and 1.5 m wide full-scale prototype ice-wedge, covered in an active layer of thickness equivalent to 0.75 m. Thermal regimes, measured pore pressures during thaw, observed thaw consolidation and measured host sediment geotechnical properties are utilised in the interpretation of casting mechanisms. During a single uniform thaw event it is shown that arching of infilling sediment and the formation of a void is likely if negative pore pressures are developed in the host sediment. In fine silt and clays high ice contents are more likely than in sands, thaw consolidation is greater, positive pore pressures encourage complete filling of the ice-wedge void, and soft sediment deformation is likely to cause deformation of the cast and reduce its width and depth. Though natural casting mechanisms are likely to be more complex than those simulated here, modelling experiments highlight the need for care when inferring original ice-wedge geometry from observed shape and size of Quaternary ice-wedge casts.

History

Publication status

  • Published

Journal

Geomorphology

ISSN

0169-555X

Issue

3-4

Volume

71

Page range

328-343

Pages

16.0

Department affiliated with

  • Geography Publications

Notes

Provides the first quantative analysis of the mechanisms and structres produced during the melt of artificial ice wedges, using a novel centrifuge method. The research integrates experimental geomorphology and soil mechanics, and was funded by the Royal Society.

Full text available

  • No

Peer reviewed?

  • Yes

Legacy Posted Date

2012-02-06

Usage metrics

    University of Sussex (Publications)

    Categories

    No categories selected

    Exports

    RefWorks
    BibTeX
    Ref. manager
    Endnote
    DataCite
    NLM
    DC