Assessment of Shear Band Characteristics in Cohesive Soils using Plane Strain Test with Digital Image Analysis

Abstract

Soil failure which affects the stability and deformation characteristics of structures is relevant to settlement by consolidation, and shear banding, the localization of deformation into thin zones. However, most of the existing researches for plane strain tests were performed with granular soils to evaluate those spatial deformations. Little research has been conducted with cohesive soils

even the existing research has no regard to spatial deformation, only considering the entire deformation which is measured by the conventional method (LVDT). Moreover, cohesive soils show significant heterogeneous deformation behaviors due to the non-uniform distribution of stress. Accordingly, the understanding of the characteristics of spatial deformation during consolidation and shear process is necessary as well as the assessment of stress-strain response of the soil. In this paper, digital image analysis technique with the advantage of high resolution for deformation at any point of a soil was adopted to evaluate the consolidation behavior and shear band characteristics of normally consolidated clays. Overall stress-strain behavior from initial to post peak has been analyzed together with spatial distributions of deformations from digital images at 5 distinct loading intervals. Failure mechanism and strain softening is strongly related to the shear band forming and evolution.