Accelerating Creep Stage of Red Sandstone Expressed and Quantitatively Identified Based on Acoustic Emission Information

Rock creep characteristics play an important role in geological engineering and have important physical implications when evaluating the long-term stability of rock structures. In this study, a series of uniaxial compression and creep experiments were performed on red sandstone specimens from Jiangxi Province, China. During experiments, stress, strain, acoustic emission (AE) parameters, and waveform files were recorded continuously. First, an AE creep model with a damping factor of red sandstone specimen was established based on the theory of statistical mechanics and damage mechanics. The intrinsic relationship between the cumulative AE events and the strain in the accelerating creep stage was revealed by a creep model derived from the inversion of experimental data in the decelerating and steady creep stages. Then, using the singular value decomposition method for cumulative AE events, quantitative identification of the accelerating creep stage of red sandstone was achieved. The evolution characteristics of b value in the creep process of red sandstone specimens are revealed. The AE signals in the decelerating creep and steady creep stages had abrupt waveforms, whereas the AE signals in the accelerating creep stage had mixed abrupt and continuous waveforms. Therefore, quantitative identification of the accelerating creep stage was achieved from the perspective of AE waveform characteristics. Finally, the relationship between the wave characteristics of AE signals and the length of microcracks in the rock was identified, and the wave characteristics of AE signals at different creep stages were considered from the perspective of elastic wave dynamics.