Pre-existing flaws can make a big difference in rock strength and deformation, and they always cause strength reduction obviously or lead to global failure of rocks under loadings. Rock failure is induced by many micro-fractures intrinsically, so the investigation on progressive failure of rock masses with pre-existing flaws contributes to presenting failure processes and mechanisms of rocks. There are also many significant practical benefits in that study. A numerical code called RFPA3D is employed herein to simulate the progressive fracturing processes of rock sample containing a pre-existing flaw subjected to uniaxial compression. The initiation, propagation and coalescence of micro-cracks are presented; therefore we can understand the whole process of rock failure clearly. Numerical results show that anti-wing cracks can initiate at flaw tips, and they will approach wing cracks. Fin cracks and shell cracks that are obtained by some researchers change to parts of the curved surface that is produced by wing cracks and anti-wing cracks in homogeneous rocks. The direct reason for the global fracture of sample is not the coalescence of wing cracks and anti-wing cracks, but one kind secondary crack. Besides, the failure of a bit homogeneous sample exhibits highly elastic and brittle characteristics. RFPA3D is a good numerical tool to simulate progressive fracturing processes of materials. This numerical study can provide some references for relevant researches.

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