Physical and mechanical characteristics of iceberg ice were studied from samples collected near the shores of eastern Newfoundland. Although the physical characteristics show considerable diversity, iceberg ice has some common features and is generally porous, lacks significant concentrations of dissolved materials, contains internal cracks and has an irregular interlocking grain structure.
A review of mechanical testing of ice was carried out and an experimental setup was devised to reduce effects of improper contact between specimen and loading apparatus. Uniaxial compressive strength for iceberg ice was determined and compared with that for lake ice. The strength of iceberg ice was higher than that of lake ice but Young I s Modulus for lake ice was higher.
Exploration for oil and gas in the continental margin of Newfoundland and Labrador has been going on for the last two decades with a commercially viable oil find at Hibernia. One of the environmental features of this region is the presence of icebergs. Icebergs, seaborne fragments of glaciers, are a common occurrence in the northern waters of Labrador and also, though not as frequent, on the Grand Banks of Newfoundland. These icebergs originate primarily from the glaciers on the west coast of Greenland.
The International Ice Patrol was fonned to monitor the icebergs in the North Atlantic shipping lanes after the sinking of the Titanic by an iceberg. As many as 1600 icebergs have been recorded south of 480N in a year and the iceberg flux is much greater at more northerly latitudes. These icebergs are carried by the current (Labrador current) and driven by stoms that frequent this region.
There are two possible impact scenarios. Offshore units (drill rigs) that are designed to move away from approaching icebergs could be hit by one that escapes detection; the smallest piece of ice that can positively be detected by available radar systems is not definitely known. The second scenario is that of a fixed offshore unit built to withstand all prevalent environmental conditions including the impact of icebergs. For both cases the impact force depends on the compliance and material properties of the structure and the iceberg. Very little is known about iceberg ice and this paper presents results of a preliminary study of iceberg properties.
Samples used in the study came from five grounded icebergs. These were highly deteriorated icebergs in the Twillingate area (#1, #2 & #3), St. John's narrows (#4), and Outer Cove area (#S).Samples were collected from calved pieces around the iceberg and in one instance a protruding piece was knocked off with an axe from the iceberg. Samples were transferred to a freezer and were not allowed toreach 0°C at any time between their aquisition and subsequent testing.
Tests were conducted to determine the physical and mechanical characteristics of icebergs including porosity, internal crack density, crystal grain structure, impurity content and uniaxial compressive strength.
