Stresses in first-year ice pressure ridges (original) (raw)

Tensile Strength of Multi-Year Pressure Ridge Sea Ice Samples

Journal of Energy Resources Technology, 1985

Thirty-six constant strain-rate uniaxial tension tests were performed on vertically oriented multi-year pressure ridge samples from the Beaufort Sea. The tests were performed on a closed-loop electro-hydraulic testing machine at two strain rates (10−5 and 10−3 s−1) and two temperatures (−20° and −5°C). This paper summarizes the sample preparation and testing techniques used in the investigation and presents data on the tensile strength, initial tangent modulus, and failure strain of the ice.

A Summary of the Strength and Modulus of Ice Samples From Multi-Year Pressure Ridges

Journal of Energy Resources Technology, 1985

Over two hundred unconfined compression tests were performed on vertical ice samples obtained from 10 multi-yr pressure ridges in the Beaufort Sea. The tests were performed on a closed-loop electrohydraulic testing machine at two strain rates (10−5 and 10−3 s−1) and two temperatures (−20° and −5°C). This paper summarizes the sample preparation and testing techniques used in the investigation and presents data on the compressive strength and initial tangent modulus of the ice.

Constitutive Models for Sea Ice Rubble in First Year Ridges: a Literature Review

2012

Exploration and production of hydrocarbons in artic areas demands stronger, lighter and safer offshore structures. Wind and sea currents are responsible for ice loads on structure. The design of these structures is based on load level which is usually determined by the drift ice features i.e. ice ridges and surrounding level ice fields if icebergs are not dominating in the area. Ridges drift and hit fixed or moored surface structures such as platforms or ships, or they may scour the seabed endangering pipelines and wellheads. Realistic Constitutive models will help to build more accurate numerical analysis of the ice load. It will decrease the capital costs for the offshore structures, resulting in more economic field development for arctic offshore. This literature review paper is focused on existing models used to simulate the constitutive behavior of the ice rubble. In the first chapter of ridge types, their formation and typical geometrical features has been discussed. The secon...

In-situ experimental investigation of the vertical stress distribution in sea ice covers; a comparison of tensile and flexural strength Proceedings of the 22nd IAHR International Symposium on Ice

The objective of the work presented in this article was to investigate the vertical stress distribution of first year sea ice covers; especially the tensile strength was compared to the flexural strength (beam capacity). For this work two scientific expeditions on sea ice were designed and executed; respectively to the Svea bay and travelling by ship (RV Lance) in the Barents sea. The ice examined in Svea was cold and brittle, showing a clear temperature gradient, while the ice examined on Lance was nearly isothermal and ductile. The experimental work consisted of; cantilever beam tests, small scale horizontal uni-axial compression tests as well as temperature and salinity measurements. Small scale uni-axial compression tests suggested that the vertical profile of the elastic modulus, E(z), was similar to the temperature profile (at least when salinities were similar). From these experiments; a non-linear stress distribution, σ (x, z), was derived for the cold brittle Svea ice, by l...

Discrete Element Analysis of High-Pressure Zones of Sea Ice on Vertical Structures

Journal of Marine Science and Engineering, 2021

In cold regions, ice pressure poses a serious threat to the safe operation of ship hulls and fixed offshore platforms. In this study, a discrete element method (DEM) with bonded particles was adapted to simulate the generation and distribution of local ice pressures during the interaction between level ice and vertical structures. The strength and failure mode of simulated sea ice under uniaxial compression were consistent with the experimental results, which verifies the accuracy of the discrete element parameters. The crushing process of sea ice acting on the vertical structure simulated by the DEM was compared with the field test. The distribution of ice pressure on the contact surface was calculated, and it was found that the local ice pressure was much greater than the global ice pressure. The high-pressure zones in sea ice are mainly caused by its simultaneous destruction, and these zones are primarily distributed near the midline of the contact area of sea ice and the structu...

Structure, Salinity and Density of Multi-Year Sea Ice Pressure Ridges

Journal of Energy Resources Technology, 1985

Data are presented on the variation of ice structure, salinity, and density in multi-year pressure ridges from the Beaufort Sea. Two continuous multi-year pressure ridge cores are examined as well as ice sample data from numerous other pressure ridges. The results suggest that the large scale properties of multi-year pressure ridges are not isotropic, and that the use of anisotropic ridge models may result in lower design ridge ice loads.

MECHANICAL PROPERTIES OF ICE RIDGES AND LEVEL ICE, IN-SITU AND LABORATORY TESTING 2003

Ice has been sampled from first-year sea ice ridges and level ice both in the Van Mijen fjord in Svalbard and in the North-western Barents Sea. In-situ drop ball test and un-confined compression tests in the laboratory were conducted on horizontal and vertical samples of ice from the consolidated layer, the rubble and the level ice. The salinity, den-sity and the ice texture was also examined. The average unconfined strength for vertical samples was 6.0 MPa for the level ice, 5.0 MPa for the consolidated layer and 3.3 MPa for the rubble. The hardness was clearly dependent on the temperature, and it varied from 11 to 37 MPa and H i ≈ H c > H r .