Avalanches in Compressed Sandstone: Crackling Noise under Confinement

Kainan Xie,Hanlong Liu,Ekhard K.H Salje,Yunfeng Zhao,Xiang Jiang

doi:10.3390/cryst9110582

Kainan Xie, Hanlong Liu + Show 3 more

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https://doi.org/10.3390/cryst9110582

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Abstract

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.

Highlights

Avalanches are manifestations of jerky responses under slowly changing fields spanning a wide parameter space
One motivation to investigate porous crackling noise emerges from practical applications, such as the need to understand: catastrophic events in the mining industry [7,13], buildings [14], crash-absorbers in cars [15], crashing bones [16], and wood [17]
We reduced the acoustic emission (AE) spectrum from the whole set to subsets of super-jerks [36]

Summary

Introduction

Avalanches are manifestations of jerky responses under slowly changing fields spanning a wide parameter space. Other dynamic physical systems with avalanches include sheared granular materials [2,3], plastically deformed crystals [4,5], ferroelectric switching [6], collapse of porous materials [7,8], neuronal networks [9], gravitational wave detection [10], and even stellar evolution [11]. Among these systems, the failure of porous materials has recently received much attention [12]. As porous materials have given the strongest avalanche signals so far, they became the model material for wider classes of materials

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