Abstract: Studies of damages in shear bands are important for obtaining a full understanding of failure mechanisms of materials, and for accurate modeling of deformations in shear bands. To study the distribution and evolution of damages in shear bands in clay specimens in uniaxial compression, monitored lines are arranged according to positions of clear shear bands along their tangential directions at higher longitudinal strains. Smooth strain fields at these lines are obtained using a bicubic spline interpolation function from results based on a digital image correlation method. The damage variable-longitudinal strain curves for entire specimens and shear bands are compared. It is found that in total the damage variable-longitudinal strain curves for entire specimens are linear, while those for shear bands are convex upward, suggesting that damage developments in shear bands become faster and faster as longitudinal strains increase. The envelop of the damage variable-longitudinal strain curves for shear bands is like a horse-tail, revealing that interactions among shear bands become intensive as deformation proceeds. For specimens with low moisture contents, changes in damage variables for shear bands are generally synchronic for parallel or co-linear shear bands, especially for well-developed shear bands, however, the shear band spacing cannot be large enough. The damages in one shear band between two conjugate or intersecting shear bands are dominant at a certain stage due to competition between them. However, if the two shear bands have developed fully, changes in damage variables can be synchronic. For specimens with high moisture contents, changes in damage variables for shear bands are generally synchronic for parallel or conjugate shear bands, reflecting weak interactions among shear bands.

Key words: clay specimen, shear band, interaction, damage variable, synchronization