Pressure-temperature effects on the compressive behavior of laboratory-grown and iceberg ice

The compressive behavior of freshwater ice subjected to a nominally constant compressive stress of 15 MPa while under confinement is investigated. Cylindrical ice specimens 155 turn in length and 70 mm in diameter were machined from polycrystalline ice made with ultra pure water and from genuine iceberg ice. The confining pressures ranged from 10 to 65 N4Pa. Test temperature varied from about - 5 to - 26 degreesC. The activation energy for the laboratory ice is determined at five distinct levels of hydrostatic pressure: 15, 35, 55, 65 and 70 MPa. It displays a substantial increase above 55 MPa. A similar increase in minimum strain rate is observed, which becomes more significant at higher temperatures. Our data are consistent with those of other investigators obtained from constant strain rate experiments. The iceberg ice tends to show a higher scatter than the laboratory ice, and is generally more compliant. Some implications for the behavior of this material upon fast compressive loading are discussed. (C) 2003 Elsevier Science B.V. All rights reserved.