oa Relationship between Parallel Faults and Stress Field in Rock Mass

Parallel cracks and faults, caused by earthquakes and crustal deformations, are often observed from regional to laboratory scales. However, the mechanism of the formation of these parallel faults has not been quantitatively clarified, yet. Since the stress field plays a key role in the nucleation of parallel faults, it is fundamentally to investigate the failure and the extension of cracks in a large-scale rock mass (not with a laboratory-scale specimen) due to mechanically loaded stress field. In this study, we developed a numerical simulation code for rock mass failures under different loading conditions, and conducted rock failure experiments using this code. We assumed a numerical rock mass consisting of basalt with a rectangular shape for the model. We also assumed the failure of rock mass in accordance with the Mohr-Coulomb criterion, and the distribution of the initial tensile and compressive strength of rock elements to be the Weibull model. In this study, we use the HPM (Hamiltonian Particle Method), one of the particle methods, to represent large deformation and the destruction of materials. Our simulation results suggest that the compression field have dominant influence for the initiation of parallel faults and their conjugates propagate in uniaxial condition. We conclude that the shearing force would not provoke the propagation of parallel fractures.