Simulation on heterogeneous rocks with a flaw using grain-based discrete-element method

To take into consideration the effect of mineral microstructure on crack growth and mechanical properties of heterogeneous rocks containing a single pre-existing flaw under uniaxial compression, the discrete-element method in combination with the grain-based model was adopted in this study. The results indicate that the characteristic stresses – that is, crack initiation stress, crack damage stress and peak strength, generally increase with respect to the inclination angle. The normalised crack initiation stress increases with the increasing angle, while the normalised crack damage stress has no pronounced change. Additionally, the variation of inclination angles has little influence on the grain-scale crack growth. The initiation of intergranular cracks is prior to the intragranular cracks, and the proportion of intragranular cracks is slightly greater than intergranular cracks at the peak failure moment. The ultimate failure patterns obtained by numerical simulations agree well with the experimental results, revealing the cracks generated from the pre-existing flaw consist of intragranular and intergranular cracks at the grain scale.