密度对各向同性冰雪应变率的影响

Effects of Ice and Snow Density on Minimum Isotropic Strain Rate

Uniaxial compression tests were performed on laboratory prepared ice samples and core ice samples. The temperature for all tests was - 3.3C and the octahedral shear stress was 0.2 MPa. 23 samples were tested, 4 of them were of laboratory prepared isotropic ice, the remaining isotropic samples were cut from BHD core, drilled near the summit of Law Dome, Antarctica. The depths of the core samples ranged from 30 to 122 m, and the densities of them ranged from 0.66 to 0.89 Mg / m3.It was found that, minimum strain rate decreases with increase of density. In the density range 0.66 to 0.80 Mg/m3, the minimum strain rate decreased by about an order of magnitude. At densities higher than 0.80 Mg/m3 however, the rate of minimum strain rate decrease was lower. The minimum strain rate at the close-off density was within a factor of two of that for dense (0.912 Mg/m3) ice. Therefore the minimum strain rates approach a constant value at densities greater than 0.83 Mg / m3.A comparison was made with the previous studies and similarities were found at the same density ranges.Total axial strain at minimum strain rate is unaffected by sample density at values above the close-off density. This parameter for sample with lower density is density dependent, increasing to 6% to 8% for a sample with density of 0.66 Mg/m3. Some of this extra strain expended in attaining minimum strain rate is due to densification of the sample. The amount of densificaiton can be measured by the volume change in the sample.