Model experimental investigation on the effects of rockburst on gently inclined structural planes under gradient stresses

The gradient stresses in the surrounding rock caused by deep excavation and the naturally occurring slow-dipping hard structural planes of the rock are critical factors influencing the characteristics of rockburst.Through triaxial loading-unidirectional unloading tests conducted on large-scale (400 mm×600 mm×1 000 mm) artificial rock specimens containing prefabricated hard slow-dipping structural planes using a gas-liquid composite loading rockburst simulation system, this study systematically investigated rockburst evolution mechanisms and mechanisms of damage. A multi-modal monitoring approach incorporating digital image correlation (DIC), acoustic emission (AE) detection, infrared thermography, and high-speed photography was employed to capture critical parameters including energy released patterns, surface infrared radiation characteristics, DIC strain field evolution, and crack propagation dynamics during rockburst development. The results of the study show that the presence of the slow-dipping structural plane has a controlling effect on the damage pattern of the specimen,greatly constrains the boundaries and morphology of rockburst craters, and accelerates the occurrence of rockburst. It is verified that the location of rockbursts in the specimens is mainly in the area between the structural planes of the specimens. The infrared radiation values and DIC strain fields in this area are much higher than those in the rest of the unloading surface before the damage. As the angle of the slow-dipping structural plane increases, the peak and cumulative acoustic emission energy of the specimen increases, the proportion of shear damage to total damage produced increaces, intensity of rockburst spawned increaces.