Based on the theory of subcritical expansion of cracks

rockfill particles breakage with the time-dependent effect is caused by the extension of microcracks. Through a new way to simulate the rheological behavior of rockfill

a series of numerical uniaxial rheological tests are carried out by the three-dimensional particle flow code method

according to the theory of subcritical expansion of cracks. The simulation results are partially compared with the lab experiments

and good agreement has been achieved. The evolution of microscopic characteristics for rockfill samples and particles breakage are presented visually during the process of numerical rheology. The analytical results show that rheology is the main results of the delayed particles breakage caused by the extension of microscopic crack

which further develops the recognition of the rheological mechanism of rockfill.