LAUSR

Stress concentrations are responsible for the crack propagation in rock and rock-like specimens. To investigate the stress evolution characteristics of the rock-like specimens containing a single prefabricated fracture, a numerical study based on the particle flow code was conducted. The numerical results indicate that the concentrated tensile stress and shear stress are responsible for the wing and secondary crack propagation. At the early compression stage, wing cracks tend to form by the concentrated tensile stress, whereas the secondary crack forms by the shear plane resulting from the shear stress concentration at later compression stage. Additionally, the increase in the inclination angle restrains the wing crack propagation. Moreover, in the propagation process of the typical wing and secondary cracks, sudden decreases of the tensile and shear stresses are observed. These decreases at the former monitor points are always accompanied with the sharp increases at the latter points. Furthermore, the results show that the wing and secondary cracks develop in different manners. The large axial strain gaps between adjacent monitor points for wing crack propagation indicates that the wing crack propagates in a stable and slow way, whereas the significantly reduced gaps indicate that the secondary crack propagates in a speedy and unstable way.