A numerical study of acoustic emission characteristics of sandstone specimen containing a hole-like flaw under uniaxial compression

For a better understanding of acoustic emission (AE) characteristics and failure mechanism of specimens containing hole-like flaw, a series of uniaxial compression tests are carried out by using the bonded-particle model (BPM). In the BPM, the AE simulation combined with moment tensor inversion is adopted. The results indicate that the stress drop in the stress-strain curve corresponds to a sudden increase of AE counts, which results from the propagation and coalescence of micro-cracks. The shape of hole-like flaw does not have a significant influence on the magnitude distribution of AE event. The b-value of three models is similar, i.e. 1.68, 1.83, and 1.75 corresponding to circular, square, and horseshoe flaw respectively. The forces concentration at upper and bottom of the hole-like flaw is dominated by tensile, and the fracture path only contains micro-tensile cracks. While the forces acting on lateral sides of the hole-like flaw are dominated by compressive. The fracture path contains both micro-tensile and micro-shear cracks and the failure nature is shear and compaction, although the number of micro-tensile crack is predominant.

Automated summary

The study conducted uniaxial compression tests using the bonded-particle model to understand the acoustic emission characteristics and failure mechanisms of specimens containing hole-like flaws. Results showed stress drops in the stress-strain curve corresponded to sudden increases in AE counts, due to micro-crack propagation and coalescence. The shape of the flaw did not significantly impact the magnitude distribution of AE events, and different regions of the flaw experienced different forces and fracture paths.