Rock mechanics, True triaxial test, Intermediate principal stress, Failure characteristic, Numerical simulation, Science (General), Q1-390, Social sciences (General), H1-99

This study performs one-sided lateral unloading- and three-way five-sided force-vertical continuous loading experiments with different intermediate principal stresses (IPS) to investigate the effect of the IPS on deformation, strength, failure modes, and acoustic emission (AE) signals of rock and to elucidate the role of the IPS on the rock strength. The inoculation, occurrence, development, and failure of rockburst as well as the AE evolution characteristics are discussed. The findings indicate that the rockburst ejection includes localized ejections of particles, spalling of rocks into plates, shearing of rocks into fragments, and ejections of rock fragments. The formation mechanism of rockburst involves three progressive processes, i.e., tensile, shear, and tensile-shear composite destruction. The peak stress of sample increases with increasing IPS, while the deformation modulus decreases exponentially as the unloading progresses. The sample properties under true triaxial unloading condition with different IPS can be described by the Mogi-Coulomb criterion. The evolution curves of ringing impact ratio (CH) and cumulative absolute energy can be divided into four stages. The crystal-scale refined model that considers mineral components efficiently simulate the rockburst. The simulated stress-strain (SS) curves of samples are in good agreement with those obtained from laboratory tests.