Author(s): Jean-Paul Nadreau; Bernard Michel
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Abstract: This paper presents information on secondary creep obtained from tests performed on freshwater (lab-made or iceberg ice) and law salinity (2 ppt) granular ice (Nadreau, 1985). The testing program included constant load uniaxial compression tests and tension tests, constant strain rate uniaxial compression tests and constant strain rate confined compression tests. Strain rate ranged from 10-9 s-1 to 10-4 s-1. The maximum confining pressure used for triaxial tests reached 70 MPa. The well-known dependence between stress and secondary creep was verified. Parameters of Glen's equation were obtained by the regression of the acquired logarithmic values of stress and strain rate. The visible increase in ice ductility when tested in a confined environment was confirmed by the values of n obtained in such tests. For uniaxial compression and tension tests the value of the n in Glen's equation is known to increase slightly as strain rate increases. The confining pressure caused the samples to behave in a ductile manner even at relatively high strain rates. The value of n for confined samples deformed at strain rates between 10-6 s-1 and 10-4 s-1 was found to be similar to values of n obtained from uniaxial tests at lower strain rates (10-8 s-1 to 10-6 s-1).
Year: 1986