Triaxial failure behavior and microfracture source time - frequency characteristics of marble under in situ stress conditions at different depths considering engineering disturbance

The safety of the surrounding rock in deep underground engineering is crucial. To understand the surrounding rock hazards at different depths of the Jinping underground cavern, triaxial compression tests were conducted, and the acoustic emission (AE) of Jinping marble samples was monitored while considering the influence of engineering disturbances and in situ stress conditions at different burial depths (100 m, 1000 m, 1400 m, 1800 m, and 2400 m). The results revealed that the AE events were dominated by small and medium-sized energy releases of magnitude 0-2, accounting for approximately 90 % of all AE events. The dominant frequency range of the microfracture sources was 0-450 kHz. As the burial depth increases, the AE frequency band aggregation time tended to stabilise at the average frequency during the loading process, and the failure mode trended towards ductile failure. This study offers theoretical support for assessing the operational security of deep underground caverns.