Rockburst failure characteristics and energy evolution law of cross-layer anchored rock mass based on optical-thermal-acoustic combinative monitoring

Weak structural planes commonly exist in underground engineering. These planes make anchor structures more prone to failure, threatening rock stability, threatening the safety and stability of underground engineering. Optical-Thermal-Acoustic (OTA) monitoring was applied during uniaxial compression tests on cross-layer anchored rock masses. The study revealed the mechanical properties, failure characteristics, and energy evolution of rock masses with different anchoring methods and bedding angles. Key findings: anchoring suppresses transverse deformation and tensile crack propagation, increasing elastic modulus and bearing capacity; anchored rock shows more intense acoustic emission but smaller infrared temperature changes; the structural plane angle controls the direction of crack extension and the evolution of the strain characteristics, and the rock is prone to instantaneous slip failure of the structural surface at 45°–75°, and the lower strength with significant IR change characteristics. Distinct OTA characteristics during rupture validate the method’s reliability for rockburst early warning and intensity assessment. Moreover, based on the failure characteristics of cross-layer anchored rock masses, a shear failure criterion for anchored structural planes is established. This criterion enables prediction of rock mass failure modes, analysis of bolt support resistance, reference for support design/construction in underground engineering within complex strata.