Freeze-bond strength experiments,: radially confined compression tests on saline and fresh water samples.

Abstract

This thesis presents and analyses the method and results from strength experiments on freeze- bonds conducted on radially confined cylindrical samples (tri-axial tests). In total sixty samples were tested successfully, divided on twenty configurations. The variables consisted of confinement, submersion time, initial temperature and salinity (8 configurations with fresh water ice and 12 with 2-3ppt saline ice). The test set-up was similar to that of Møllegaard [2012] and Shafrova and Høyland [2008], uni-axial experiments were also conducted in order to ensure comparability. The measured freeze-bond shear stress found for the uni-axial samples were in the range of 170 - 800kPa (submersion times of 0.5 - 20 min).The objective was to study the internal freeze-bond stress in relation to increasing radial confinement together with the variables; salinity, initial temperature and submersion time. And as well how to best conduct these experiments.A large part of the configurations gave increasing stress for increasing confinement, both when studying the peak and residual stress plots. Mohr-Coulomb failure criterion was applied, the peak stress plots gave estimated cohesion values in the range 0.003 - 0.099 MPa and 16.21 - 44.70° for internal friction. For the residual stresses the cohesion values were approaching zero and the internal frictions were in the range 11.21 - 36.70°. In relation to initial temperature the lowest initial temperature of -8.5°C gave the highest cohesion values. And the configurations with fresh samples were found to have a mean cohesion value 30% higher than for the saline.