Statistial analyses of maximum shear strain fields for wet soil specimens in uniaxial compression using digital image correlation

The evolution of the mean and standard deviations of the maximum shear strains for wet soil specimens in uniaxial compression and the size of the shear localization region are studied. To explore the occurrence and development of shear bands, some monitored lines are arranged in the specimens according to the positions of apparent shear bands at higher longitudinal strains. The maximum shear strains at these lines are obtained using a bicubic spline interpolation function with good smoothness from the results based on the digital image correlation method. It is found that the distribution of the maximum shear strains along shear bands transits from several peaks with lower values to a few main peaks with higher values with the increase of the longitudinal strain. These main peaks originate from the positions where the maximum shear strains increase rapidly and from those with local higher or lower values. Generally, the mean and standard deviations of the maximum shear strains at monitored lines are convex upwards with the increase of the longitudinal strain. However, at lower longitudinal strains, the two statistical quantities are linear. The mean of the maximum shear strain corresponding to the end of the linear stage of statistical quantities is regarded as the occurrence of shear bands. The size of the shear localization region increases with the increase of the longitudinal strain. For the same size of the shear localization region, the specimens with higher water contents require higher longitudinal strains. At higher longitudinal strains, the size of the shear localization region for the specimens with higher water contents is larger than that with lower water contents, which is related to its longer stage of plastic deformation.