The force exerted by a moving ice sheet on an offshore structure

Ponter, A. R. S.; Palmer, Andrew; Goodman, D. J.; Ashby, Michael F.; Evans, A.G.; Hutchinson, John W.

doi:10.1016/0165-232x(83)90002-2

Cited by 48 publications

(16 citation statements)

References 10 publications

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“…Later, plastic limit analysis was applied to the problem (Ralston, 1978), where ice strength is limited by a plastic yield. The reference stress method was also applied (Ponter et al, 1983), where ice failure by creep deformation is assumed.…”

Section: Introductionmentioning

confidence: 99%

Strength and Failure Modes of Pure Ice and Multi-Year Sea Ice Under Triaxial Loading

Murrell

Sammonds

Rist

1991

Ice-Structure Interaction

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Following a brief description of a new servo-controlled triaxial testing system for large ice samples (ca. 40mm diameter) with facilities for acoustic emission (AE) observations, and of a technique for manufacturing pure ice samples, laboratory results are presented for the strength of ice under uniaxial tension, and under uniaxial and triaxial compression. Data has been gathered using strain rates up to 10-2 /s, confining pressures up to 30MPa and temperatures down to -40°C. The pure ice had a uniform grain size of about 1mm and a high density. The sea ice, collected from the Canadian High Arctic, had a large natural variability of structure, salinity and density. The test conditions straddle the boundary between brittle cracking and fracture behaviour, and high temperature plasticity. The behaviour shows some similarities with that of silicate rocks and covalent oxides. At low temperatures and high strain rates ice fracture exhibits a pressure dependence similar to that of brittle rocks, with strength increasing as confining pressure increases. AE is also similar to that of brittle rocks. However, at higher temperatures and pressures, where ductile behaviour occurs, increasing pressure leads to decreasing strength. The peak strengths observed during ductile behaviour are not yet fully understood. The results are discussed in terms of Griffith crack theory.

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Section: Introductionmentioning

confidence: 99%

Strength and Failure Modes of Pure Ice and Multi-Year Sea Ice Under Triaxial Loading

Murrell

Sammonds

Rist

1991

Ice-Structure Interaction

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“…The indentation rate _ u of a rigid indenter of the width b into ice with an exponent n = 3 can be written as [18,29,34] …”

Section: Comparison To Indentation Analysismentioning

confidence: 99%

Foundations of cable car towers upon alpine glaciers

Fellin

Lackinger

2007

Acta Geotech.

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This paper presents a design approach for strip footings upon glacier ice. Safety against ultimate limit state is proved by the geotechnical slip-line field solution by Prandtl. Glacier ice at 0°C can be modelled as purely cohesive material. Statistical evaluation of uniaxial compression tests with high strain rate revealed a mean value of the cohesion of 600 kPa and a characteristic value c k = 355 kPa (5% fractile). With a coefficient of variation V c = 0.3, the partial safety factor turns out to be c c = 1.9. An approximate solution for estimating the creep settlement rate _ u is presented to check the serviceability limit state:with the width b of the strip foundation, p the foundation pressure and b 1 ¼ 8:6 Â 10 À5 m kPa Àb 3 a À1 m 1Àb 2 ; b 2 ¼ 0:92; b 3 ¼ 1:74 for ice at 0°C. Experiences on Stubai glacier with grate shaped footings showed that creep settlements occurring per year due to maximum foundation pressures 250 kPa did not influence the operation and the maintenance of the cable cars.

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“…This study (which was described in much more detail in the preprint distributed at the Fairbanks workshop, Bazant 2000), will appear in full detail in the forthcoming journal article by Bazant (2002). Owing to space limit, discussions of previous ice fracture and scaling studies (Ashton 1986, Atkins 1975, Dempsey et aI, 1995, 1999a, Goldstein and Osipenko 1993, Palmer 1983, Ponter 1983, Slepyan 1990 must be relegated to that article.…”

Section: Iutam Symposium On Scaling Laws In Lee Mechanics and Leementioning

confidence: 99%

Scaling Laws for Sea Ice Fracture

Bažant

2001

IUTAM Symposium on Scaling Laws in Ice Mechanics and Ice Dynamics

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Based on the premise (recently validated by Dempsey's in-situ tests) that large-scale failure of sea ice is governed by cohesive fracture mechanics, the paper presents simplified analytical solutions for (1) the load capacity of floating ice plate subjected to vertical load and (2) the horizontal force exerted by an ice plated moving against a fixed structure. The solutions clarify the fracture mechanism and agree with the previous numerical simulations based on cohesive fracture mechanics. They confirm the presence of a strong deterministic size effect. For the case of vertical load, the size effect approximately follows the size effect law proposed in 1984 by Baiant. In the case of an ice plate moving against a fixed obstacle, radial cleavage of the ice plate in the direction opposite to ice movement causes a size effect of structure diameter which follows linear elastic fracture mechanics for small enough diameters but becomes progressively weaker as the diameter increases. The present solutions contradict the earlier solutions based on material strength or plasticity theories, which exhibit no size effect.

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The force exerted by a moving ice sheet on an offshore structure

Cited by 48 publications

References 10 publications

Strength and Failure Modes of Pure Ice and Multi-Year Sea Ice Under Triaxial Loading

Strength and Failure Modes of Pure Ice and Multi-Year Sea Ice Under Triaxial Loading

Foundations of cable car towers upon alpine glaciers

Scaling Laws for Sea Ice Fracture

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