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Avalanches in Compressed Sandstone: Crackling Noise under Confinement

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School of Civil Engineering, Chongqing University, Chongqing 400044, China
2
State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing 400044, China
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Departament de Física de la Matèria Condensada, Facultat de Física, Universitat de Barcelona, Martíi Franquès, 1. 08028 Barcelona, Catalonia
4
Department of Earth Sciences, University of Cambridge, Cambridge CB2 3EQ, UK
*
Author to whom correspondence should be addressed.
Crystals 2019, 9(11), 582; https://doi.org/10.3390/cryst9110582
Received: 12 October 2019 / Revised: 3 November 2019 / Accepted: 6 November 2019 / Published: 7 November 2019
The acoustic emission, AE, from avalanches of local cracks and microstructural changes of sandstone under confined compression have been reported. These avalanches soften the underlying minerals and play a key role as indicators for the prediction of geo-engineering disasters, such as mining collapses, rock outbursts caused by high ground stress, and man-made quakes by fracking. Compressed sandstone is a model material for the investigation of avalanches. The avalanche energies, amplitudes, and waiting times show the probability distributions that allow us to distinguish between three compression stages; namely, (I) pre-failure, (II) correlated failure, and (III) post-failure. The energy of stage I and stage II is power-law distributed and scale invariant, while post-failure experiments show power laws with high exponential damping (friction). The scaling behavior is close to the predictions of a mean-field (MF) model (stage II) and a force-integrated mean-field model (stage I). Confinement shifts the value of the energy exponent closer to the MF prediction. Omori’s law and waiting time distributions are independent of stress during the compression; their scaling exponents are very similar to those found in seismological studies. View Full-Text
Keywords: sandstone; acoustic emission; crackling noise; mean-field model sandstone; acoustic emission; crackling noise; mean-field model
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Zhao, Y.; Liu, H.; Xie, K.; Salje, E.K.; Jiang, X. Avalanches in Compressed Sandstone: Crackling Noise under Confinement. Crystals 2019, 9, 582.

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