Roles of model size and particle size distribution on macro-mechanical properties of Lac du Bonnet granite using flat-joint model

In this study, a new calibration procedure was proposed to calibrate the micro-parameters for the flat-joint model. Both uniaxial compression and Brazilian test simulations were conducted on standard and same-porosity specimens using flat-joint model. With increasing model size, the uniaxial compression strength (UCS), crackinitiation stress, Young's modulus and Poisson's ratio decrease initially until achieving stable values, while the Brazilian tensile strength (BTS) follows the descending trend and UCS/BTS maintains increasing with increasing model size. It is found that BTS is best fitted by the fracture energy and multifractal size-effect models for which the fitting constants are functions of the grain size heterogeneity (d(max)/d(min)). All the macro-properties are found to decrease with increasing d(max)/d(min). It is also demonstrated that the constitutive contact model affects the effects of model size and particle size distribution.