| Abstract | The report summarises the results from three series of plunge tests on ice rubble conducted at the University of Calgary, and interpretation of these results. The tests were conducted as two-dimensional plane strain experiments in a transparent tank that permitted video recording of the rubble behaviour during the tests. The majority of the tests were conducted using standard fresh-water ice cubes manufactured using commercial ice making machines, while the most recent tests were conducted using larger ice pieces. The observations of the behaviour of the rubble during the tests suggested that there was a significant difference in behaviour observed at low and high loading speeds. At low speeds, well-defined failure planes were observed, and, for unconsolidated rubble, the behaviour could be described as purely frictional. As the ice was permitted to consolidate, the addition of local regelation altered the value of the angle of friction, but the observed behaviour was little changed. Over the range of low speed tests ( to 40 mm/sec) there was no appreciable effect of speed on friction angle. However, there is some effect of rubble thickness. At high speeds of loading, no clearly defined failure planes were observed. The failure could be described as gradual, with the disturbance of the ice rubble taking place within the mass of the rubble. The analogy used for the interpretation of the strength of the rubble (plate pull-out in granular materials) was not applicable to these tests. The analysis of these results, and the extension of the test programme for the larger ice pieces, is on-going. |
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