The General Particle Dynamics (GPD), which is a novel meshless numerical method, is pro-posed to simulate initiation and propagation and coalescence of the 3D pre-existing penetrating and embedded flaws under biaxial compression. Failure process of rock-like materials subjected to biaxial compressive loads is investigated using the numerical code GPD3D. Moreover, the internal crack evolution processes are successfully simulated using GPD3D. With increasing lateral stress, the secondary cracks keep growing in the samples, while the growth of wing cracks is restrained. The samples subjected to biaxial compression are mainly splitted into fragments in a shear failure mode, which is different from splitting failure of the samples subjected to uniaxial compression. For specimens with macroscopic preexisting flaws, the simulated failure modes, the simulated coalescence types and the simulated types of cracks are in good agreement with the experimental results.


Rock mass is heterogeneous geomaterial with various types of pre-existing flaws. The initiation, propagation and coalescence of these pre-existing flaws under loading are significant in the study of rock engineering. The initiation, propagation and coalescences of pre-existing flaws play a decisive role in the mechanical properties of rock mass. Extensive study has been done on crack propagation in different materials under uniaxial compression in 2D physical experimental works (Bobet and Einstein, 1998; Lee and Jeon, 2011; Park and Bobet, 2009; Park and Bobet, 2010; Sagong and Bobet, 2002; Wong and Einstein, 2009a,b; Wong et al., 2001; Zhou et al., 2013) and numerical studies (Zhouet al., 2013; Bobet and Einstein, 1998; Liu et al., 2004; Ning et al., 20lla,b; Tang et al., 2001). Although there are many differences in the crack pattern observed by those researchers, there are also common characteristics. Two types of cracks have been regularly observed: primary cracks and secondary cracks. Primary cracks or Wing cracks appear first; they are tensile cracks which start at the tips of the flaw and propagate in a smooth path as the load is increased. Secondary cracks appear later and are responsible, in most cases, for specimen failure; they are described by many authors as shear cracks. Secondary cracks in most cases initiate in a direction coplanar to the pre-existing flaw.

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