Stress Localization in Brittle Rock-Like Samples of Particle-Filled Joints under Direct Shear Loading

Abstract

The mechanical strength and stability of particulate materials are controlled by their frictional behavior, which plays a vital role in evolving of landslides and geological hazards. While deformation of particles is closely related to the stress localization, the shear displacement processes controlling local stresses are difficult to be observed directly. In this paper, the laboratory direct shear experiments were designed to explore the relationship between local stresses and particles’ behavior, as well as clarify the particle size effect on the particle-filled joint’s mechanical properties. A new method was proposed, which combined the 3D scanning technology and statistical analysis for reconstructing the aperture distribution evolution during the shear process. The local stress regions were assessed by analyzing the aperture evolution. The direct shear tests on artificial joints filled with particles of different sizes were conducted with a normal load of 30 kN. The results obtained proved that the filled joint’s mechanical behavior had a close correlation with the particle size, which involved not only the peak strength but also the residual shear strength. The particles’ deformation determined the normal strain, while the shear displacement controlled the aperture distribution, further influencing the local stress. Three modes of particle deformation were proposed based on the analysis of mechanical behavior and the local stress region. The findings of this study are considered instrumental in investigating failure mechanism with an increasing fault or landslide displacement that may trigger localization—delocalization events and, therefore, control the macroscopic stability and prevent the occurrence of potential geological hazards.