Strain localization of a frozen sand under different test conditions

In this paper, a series of plane strain tests were conducted on a coarse frozen sand under different temperatures and loading conditions of constant strain rate and stress. With the overall strain fields obtained with particle image velocimetry (PIV) technique, the influence of loading conditions, temperature and strain rate on the strain localization characteristics of the frozen sand was analyzed. It is indicated that, under the same loading conditions, the temperature and strain rate have little influence on the shear band formation process. Both of the single and X shape shear band are observed under different test conditions. The X shape shear bands are more likely to be generated under strain rate lower than the magnitude of 10(-3) min(-1). When the sand samples are at failure, most part of the strain field is at dilatancy state. The shear band inclination angle and width are inversely proportional to the temperature and independent of strain rate and loading conditions. Further analysis indicated that, within the testing temperature range in this study, the widely accepted Coulomb's solution of unfrozen soils is applicable as the upper bound of the measured shear band inclination angle of the tested frozen sand, and the measured shear band width falls in the range of 10 to 20 times of mean particle size.

Automated summary

This study conducted plane strain tests on coarse frozen sand under different temperatures and loading conditions, analyzing the strain localization characteristics with PIV technique. The results show that temperature and strain rate have little influence on shear band formation, and X shape shear bands are more likely to be generated at lower strain rates. Additionally, most of the strain field is in a dilatancy state at failure, and the shear band inclination angle and width are inversely proportional to temperature.