ANALYSIS OF SIZE EFFECT, SHEARDEFORMATION AND DILATION IN DIRECT SHEAR TEST BASED ON GRADIENTDEPENDENT PLASTICITY

The paper concerns the issue of size law, localized deformation and dilation or compaction due to shearlocalization. It is assumed that the shear localization initiates at the peak shear stress in the form of single shear band, andbased on gradient-dependent plasticity, an analytical solution on size effect or snap-back is obtained. The results show thatthe post peak response becomes steeper and even exhibits snap-back with increasing of length. For small specimen, therelative shear displacement when specimen failure occurs is lower than that of larger specimen and the shearstress-relative displacement curve becomes steeper. The theoretical solution on non-uniformity of strains in shear band isobtained and evolution of the relative shear displacement is represented. By resorting to the linear relation between localplastic shear strain and local plastic volumetric strain, the dilation and compaction within shear band are analyzed.Relation between apparent shear strain and apparent normal strain and relation between shear displacement and verticaldisplacement are established.