Strain localization patterns of cohesive soil with controlled microfabric under cyclic loading using DIA technique

This paper focuses on the shear behavior and strain localization patterns of cohesive soil under cyclic and drained/undrained (axial) loading conditions for soil's two extreme microfabrics using lubricated end boundary cyclic triaxial system facilitated with DIA setup. The Digital Image Analysis (DIA) is an advanced technique for studying the strain localization patterns of soil, which has been developed for the cyclic triaxial system and used throughout this experimental research. The impact of soil's microfabric (dispersed/flocculated), specimen's boundary conditions (Lubricated-end/Frictional-end), equipment's testing and loading conditions (drained/undrained, axial/cyclic) on strain localization patterns of Kaolin clay has been studied using obtained experimental data. This research reveals that the initiation and formation of intense straining zones occurs at much earlier stage of shearing in undrained tests than the drained tests. In cyclic triaxial tests, the strain localization patterns at low strain levels shows the linear shear banding in compression & extension modes of a cycle and undefined zones of intense straining at the end of the cycle. At higher strain levels of cyclic loading, the maximum local strain experienced by the soil in a test has been observed to be significantly higher in dispersed microfabric as compared to the flocculated.