A granular anisotropic model of underground rockburst considering the effect of radial stresses

• Introduced a novel granular model for analysing rockburst mechanisms. • Validated the true triaxial rockburst model with experimental correlations. • Identified reduction in rockburst strength due to anisotropy angle variations. • Documented diverse micro-crack evolution associated with anisotropic changes. Rockbursts pose significant concerns in underground construction, and understanding their mechanisms is crucial for enhancing safety in tunneling and underground mining operations. This study innovates an inherently anisotropic rock model using the discrete element method to investigate the effect of local strength degradation on rockburst behavior. Unlike the existing rockburst models in which the anisotropy is either not accounted for or simulated by creating transversely weak planes, the inherent anisotropy is achieved in the contacts between rock grains. Following model calibration, the accuracy of the proposed model is demonstrated by simulating the behavior of rock samples subjected to triaxial rockburst tests. The findings highlight the influence of loading conditions on rockburst behavior in inherently anisotropic rocks and compare micro-crack patterns after rockbursts under different triaxial loading stresses and mesoscale failure types. Notably, this study is the first attempt to combine an inherently anisotropic rock model with rockburst analysis, providing new insights into the mesoscale mechanisms underlying rockburst failure. Notably, it reveals a significant variation in rockburst strength, by about a third, when the anisotropy angle shifts from 0 to 90 degrees. The proposed inherently anisotropic rock model offers an alternative for evaluating the impact of grain-scale strength degradation on rockburst behavior.