Failure mechanism evaluation in normally consolidated cohesive soils by plane strain test with digital image analysis

Soil failure is initiated and preceded by forming and progressing of shear band, defined as the localization of deformation into thin zones of soil mass. To understand the failure mechanism of soil, the spatial distribution and evolution of deformation within the entire specimen need to be evaluated. In cohesive soils, significant heterogeneous deformation behaviors due to the non-uniform distribution of stress may be observed. In this study, vertical compression tests under plane strain condition were performed on reconstituted kaolinite specimens, while capturing digital images of the specimen at regular intervals during consolidation and shearing. Overall stress-strain behavior from initial to post peak has been analyzed together with spatial distributions of deformations from digital images at 4 distinct loading intervals. Failure mechanism and strain softening is strongly related to the shear band forming and evolution.