On the size-dependent compressive resistance of bonded granules

Peculiar properties of cemented geomaterials are endowed by inter-particle bonds, of which the contact behaviour has recently been found to be size dependent. This study uses the distinct-element method to investigate the size effect on the compressive resistance of an inter-particle bond, which is modelled as an assemblage of tiny bonded particles. The model parameters are carefully calibrated according to laboratory observation of a realistic reference material. The simulations demonstrate that the compressive resistance of the bond largely depends on bond slenderness and boundary curvature as well as the bond contact area. The combined effect of three size parameters can be captured in a single formula. Given the bond contact area in common, a thin bond between large particles tends to fail at higher compressive force than a thick bond between small particles because the coalescence of micro-cracks inside the bond is hindered more effectively in the thin case, resulting in ultimate failure due to compressive crushing rather than tensile cracking. A full consideration of the size effect on the bond contact strength may change the picture of progressive bond breakage in cemented geomaterials, which deserves further investigation once a size-dependent bond contact law is obtained.