The Effect of Indentation Rate on Rock Breakages Characteristics

To investigate the influence of indentation rate on the fracture characteristics, first laboratory indentation tests were performed. The laboratory tests show that the peak indentation force increases with the increase in the indentation rate. However, the increase in indentation rate restrains the crack propagation. Then, numerical indentation tests, using PFC 2D, were conducted to verify the laboratory results. For the crack propagation and the peak indentation force, the numerical and laboratory results are consistent. To further study the underlying mechanism, the stress conditions before and after the median crack propagation were analyzed. The results shows that the increase in indentation rate significantly promotes the fracture toughness and thus restrains the crack length.