Study on strain localization of frozen sand based on uniaxial compression test and discrete element simulation

Strain localization has always been an important subject in frozen soil mechanics and engineering. To evaluate the development of local strain and the formation of shear bands in frozen soil, uniaxial compression tests have been conducted on frozen sand at various temperatures and particle grades. The strain localization evolution law of the frozen soil is analyzed utilizing the digital image correlation (DIC) method. The test results reveal that the entire process of shear band generation, development, and formation in frozen soil can be well captured. Within the testing temperature and particle grade range in this study, in comparison to particle grade, temperature exerts a more pronounced influence on the shear band angle which increases as temperature decreases. It is discovered that the width of the shear band increases with the decrease in temperature and the increase in mean particle diameter d₅₀. Subsequently, a discrete element method (DEM) model is developed to examine the microscopic mechanical characteristics of frozen sand in uniaxial compression tests. The reliability of the DEM model is verified through comparative analysis with test results. Besides, the development law of the strain localization of the frozen soil obtained by the numerical simulation is revealed based on the quantitative analysis of the rotational angle, bonding state, and displacement of the soil particle during the shearing process.