Comparative Analysis of the Spatiotemporal Evolution Patterns of Acoustic Emission Source Localization Under True...

Area of Science:

• Geotechnical Engineering
• Rock Mechanics
• Materials Science

Background:

• Microseismic/acoustic emission (AE) monitoring provides real-time, non-destructive insights into rock deformation and failure.
• Understanding rock failure mechanisms under different stress paths is crucial for geological hazard assessment and engineering design.

Purpose of the Study:

• To comparatively investigate the spatiotemporal evolution of AE during sandstone failure under pure loading versus load-unloading conditions.
• To analyze AE waveform parameters and source locations to characterize distinct failure patterns.

Main Methods:

• Experimental design involving sandstone subjected to two distinct stress paths: pure loading and load-unloading.
• Acquisition and analysis of AE waveform time-frequency parameters and source location data.
• Comparative analysis of failure evolution patterns based on AE characteristics.

Main Results:

• Both loading paths showed a four-stage failure process. Unloading induced premature fracturing with a more pronounced AE response compared to pure loading.
• Dominant AE frequencies were 0-200 kHz, with a notable low-frequency, high-amplitude zone during the final failure stage (Stage 4).
• Load-unloading revealed tensile crack nucleation (Stage 3) and subsequent propagation/coalescence (Stage 4), forming macroscopic fractures.
• Pure loading indicated compression-shear fracture development (Stage 3) and propagation into a through-going shear plane (Stage 4).

Conclusions:

• Rock failure mechanisms differ significantly between pure loading and load-unloading stress paths.
• AE monitoring effectively captures the spatiotemporal evolution of rock failure, distinguishing between tensile and shear fracture modes.
• The findings enhance the understanding of rock mass behavior under complex stress conditions, relevant for geomechanical applications.