Shear Response of Non-Dilative Interfaces: A Micromechanical Perspective

The study investigates the effect of particle shape, hardness of continuum material, and normal load on the shear response of non-dilative geomaterial contacts using custom-built micromechanical shear testing apparatus. For this study, two different types of particulate materials (sub-angular sand and rounded glass beads) and continuum materials (smooth geomembrane and steel) are selected to test four different types of interface contacts. The results reveal that the friction coefficient and mechanism are dependent on the particle shape, continuum material hardness, and normal load. The friction coefficient increases with an increase in the angularity of the particle and decreases with an increase in the hardness of the continuum material. The friction coefficient initially decreases and then increases with an increase in normal load due to change in frictional mechanism from sliding to plowing at the critical normal load. The critical normal load decreases with an increase in angularity and increases with increase in hardness. Further, the mechanism change is corroborated with the shear-induced surface changes measured using a stylus profilometer.