Progressive Failure Process of Sandstone Under Different Loading Conditions via Acoustic Emission Characteristics

ABSTRACT This study investigates the acoustic emission (AE) characteristics during sandstone failure under three typical mechanical tests:direct shear test (DST), Brazilian splitting test (BST), and uniaxial compression test (UCT). Results show a significant difference in the log‐linear slope between AE count and amplitude across different tests, reflecting variations in the scaling distribution characteristics of AE signals. Peak frequency distributions vary, with DST predominantly in the 150‐ to 200‐kHz range, BST in the 0‐ to 100‐kHz range, and UCT showing a mixed distribution. RA (rise time/amplitude) and AF (counts/duration) analysis classified crack types, indicating shear‐type signals dominate in DST, tensile‐type signals in BST, and a slight dominance of tensile cracks in UCT. Shear cracks generally exhibit higher AE energy, especially in high‐energy ranges (10–1000 mV*mS), whereas tensile cracks dominate the low‐energy range (0.1–1 mV*mS). These findings advance the understanding of rock failure mechanisms and AE signal behavior.