Uniaxial Compression Creep Characteristics and Acoustic Emission Characteristics of Two Different Kinds of Red Sandstone with Different Particle Sizes

In this study, we tested uniaxial compression deformation and uniaxial compression creep on red sandstone specimens with fine- and medium-sized particles; microstructure development and acoustic emission (AE) were recorded. The creep deformation characteristics and AE parameters of these two kinds of sandstone specimens were then compared and analysed. Results show that the microstructure of fine-grained sandstone is the granular sand-like structure, and the medium-grained sandstone has a grain-like microstructure. The particle size obviously influences uniaxial compressive mechanism; the medium-grained sandstone has a higher creep deformation than the fine-grained sandstone, while the AE amplitude, AE event rate and AE ring-down count rate of the medium- and fine-grained sandstone specimens have similar trend during the creep stage. The failure of both medium- and fine-grained sandstone mainly occurs in the transient and accelerated creep stages during the creep process. By combining the variation of AE parameters and AE-r value (the ratio of the accumulative hits and the cumulative energy) in the various creep stages, we found the creep damage to sandstone could be predicted to a certain extent.