Numerical investigation of the influence of specimen size on the unconfined strength of defected rocks

A grain-based distinct element model (GBM) is used to investigate the influence of specimen size on the strength of intact (not defected) and defected rocks. The defected specimens are simulated by integrating a previously calibrated GBM with Discrete Fracture Network models representing defect geometries. The results of scale effect analysis conducted on synthetic specimens show that the strength of intact specimens is independent of specimen size. However, depending on the orientation of defects relative to the loading direction, the strength of defected specimens may decrease, increase or fluctuate with increasing specimen size.