The Non-coaxiality and Fabric Evolution of Granular Materials in Mixed Load and Unload on Deviatoric Plane

Abstract

The non-coaxiality and fabric evolution of granular materials with the stress path of mixed load and unload on deviatoric plane have not been well understood, particularly for mixed unload. This study is to survey the combined influence of intermediate principal stress ratio b-value, stress ratio level, confining pressure, and inter-particle friction on the deformation, non-coaxiality by true triaxial simulations with DEM (discrete element method), in mixed loads and unloads, and their correlation to micro-fabric evolution. Differences in deformation, non-coaxiality, and fabric evolution results are analyzed. The non-coaxiality is closely related to stress increment direction, the current stress state, confining pressure\({\sigma _c}\), and inter-particle friction coefficient\(\mu\), with distinct non-coaxial response in mixed unloads. It further verifies that the magnitude and orientation evolution of contact fabric are responsible for the deformation and non-coaxial response in mixed load and unload.