Acoustic Emission Time–Frequency Characteristics and Response Mechanism of Damaged Sandstone Under the Influence of Lithology

Coal seam mining will inevitably cause damage to overlying rock structure, and then affect mine safety production, and even surface ecological environment. This study investigates two types of damaged sandstone samples, prepared through cyclic loading–unloading and uniaxial compression tests. The mechanical properties and time–frequency distribution of the damaged sandstone samples were analyzed, revealing the acoustic emission (AE) response mechanism across different lithologies. High‐frequency, low‐energy AE signals (400–800 kHz, 0–250 aJ) transition from sporadic to dense as damage increases, with a significant rise in frequencies above 400 kHz, indicating internal rock damage. The appearance of low‐frequency, high‐energy signals (25–120 kHz, 4000+ aJ) signals impending rock failure. Additionally, the particle distribution and bonding mode in the rock influence its mechanical properties and AE response. These findings provide valuable insights for rock damage identification in western mining areas.