Experimental investigation of pressure stimulated currents and acoustic emissions from sandstone and gabbro samples subjected to multi-stage uniaxial loading

The pressure stimulated currents (PSCs) and acoustic emissions (AEs) simultaneously emitting from rocks during deformation and fracturing are gradually receiving attention for rock dynamic disaster monitoring in underground excavations (mines and tunnels). For the work described in this paper, PSC signals and AE counts were recorded simultaneously during the multi-stage loading of two types of rock samples, sandstone, and gabbro. The PSC’s and AE’s responses to stress changes are studied and compared. The AEs are analyzed to investigate the changes in microcracking and energy dissipation in the two lithologies during uniaxial compression. Using an atomic force microscope, a polarized light microscopy, and a scanning electron microscope, the PSC electrification mechanisms and their correlation with AE responses are discussed. The results show that PSC signals respond more quickly to stress changes than AEs; this is especially true for the sandstone because it has fewer microcracks than the gabbro during the early loading stages. Both the electrification mechanisms and energy dissipation are affected by differences in mineralogy and microcracking, and these differences could account for the different PSC and AE responses observed in the sandstone and gabbro. Both the PSCs and AEs increase as rock damage increases, and the PSC-AE activity can provide warnings before catastrophic rock failures. Microstructural analysis reveals that mobile dislocations and microcrack propagation are joint mechanisms for generating simultaneous PSC and AE signals. This study offers critical insights into simultaneously using PSC and AE responses for geological disaster monitoring and forecasting in deep underground mines.