Velocity-Free MS/AE Source Location Method for Three-Dimensional Hole-Containing Structures

Dong, Longjun; Hu, Qingchun; Tong, Xiaojie; Liu, Youfang

doi:10.1016/j.eng.2019.12.016

Cited by 124 publications

(42 citation statements)

References 24 publications

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“…In the last stage of loading (Stage E), the rock sample has shown visible macroscopic cracks. The positioning results of AE events are obtained by the localization method without using premeasured velocity based on the A* search algorithm [38]. We projected the events with DC components greater than 60% onto the rock sample (Figure 9) to analyze the effect of such events on crack development.…”

Section: Fracture Types Of Granite In Post-peakmentioning

confidence: 99%

Micro-Crack Mechanism in the Fracture Evolution of Saturated Granite and Enlightenment to the Precursors of Instability

Dong

Zhang

2020

Sensors

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To explore the potential precursors of rock instability, it is necessary to clarify the mechanism of micro-crack from fracturing to failure, which involves the evolution of fracture size, orientation, source model, and their relationships to the loading. The waveforms of acoustic emission (AE) recorded by the sensor network attached rock sample during laboratory tests provide a data basis for solving these problems, since these observations are directly related to the characteristics of the fracturing sources. Firstly, we investigated the source mechanism, looking at the rise angle and the average frequency (RA-AF) trends during five loading stages in a uniaxial compression test. Results show that the proportion of shear events significantly increases when approaching instability. Secondly, we calculated the moment tensor for each event, considering the uncertainties of P-wave polarity, azimuth, and the takeoff angles of the rays. Moment tensor solutions suggest that there are obviously more crack events than shear events in all loading stages. Moment tensor evolutions confirmed that the decreasing of isotropic component and the increment of double-couple can be used as precursors of rock fracturing development. Considering the limitations of these two methods, it is suggested that we should be concerned more about the proportions of individual failure components and their evolutions over time, instead of absolutely classifying the events into a certain source type.

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Section: Fracture Types Of Granite In Post-peakmentioning

confidence: 99%

Micro-Crack Mechanism in the Fracture Evolution of Saturated Granite and Enlightenment to the Precursors of Instability

Dong

Zhang

2020

Sensors

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“…For example, the phrases "streamer em" and "receiver deghosting" grew in occurrence at a very fast rate during 2011-2015, but since 2015, they have been declining as quickly as they were growing before. The word "fiber" and "fibre" ("The British spelling of fiber" [27]) is increasing in use almost as rapidly; this refers to fiber optics, because seismic sensors based on fiber optics are now growing in use, and because of their effectiveness in detecting faults filled with geothermal fluids [28], microseismic monitoring of hydraulic fracturing [29][30][31], and other applications. The term "distributed acoustic sensing" (DAS) shows good correspondence with the word "fiber" as DAS is based on fiber optics, and these terms are closely associated.…”

Section: Discussionmentioning

confidence: 99%

Text Analysis Reveals Major Trends in Exploration Geophysics

Eltsov¹,

Yutkin²,

Patzek³

2020

Energies

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Evolution of professional language reveals advances in geophysics: researchers enthusiastically describe new methods of surveying, data processing techniques, and objects of their study. Geophysicists publish their cutting-edge research in the proceedings of international conferences to share their achievements with the world. Tracking changes in the professional language allows one to identify trends and current state of science. Here, we explain our text analysis of the last 30 annual conferences organized by the Society of Exploration Geophysicists (SEG). These conferences are among the largest geophysical gatherings worldwide. We split the 21,864 SEG articles into 52 million words and phrases, and analyze changes in their usage frequency over time. For example, we find that in 2019, the phrase “neural network” was used more often than “field data.” The word “shale” became less commonly used, but the term “unconventional” grew in frequency. An analysis of conference materials and metadata allows one to identify trends in a specific field of knowledge and predict its development in the near future.

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“…These studies emphasized constructing the velocity discontinuities, including Conrad and Moho discontinuities. It was reported that the accuracy of the tomographic study on hole-contained structures can be improved by a velocity-free source location method (Dong et al 2020). The likely influences from the goafs were not included in this study due to a certain limit on the daily production data.…”

Section: Methodsmentioning

confidence: 99%

Passive Seismic Imaging of Stress Evolution with Mining-Induced Seismicity at Hard-Rock Deep Mines

Westman

Counter

et al. 2020

Rock Mech Rock Eng

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This work aims to examine the stress redistribution with evolving seismicity rates using a passive seismic tomographic tool. We compiled a total of 26,000 events from two underground mines and partitioned them into multiple clusters in a temporal sequence, each of which contains 1000 events. To image stress redistribution associated with seismicity rates, we then run the tomographic studies using each cluster to yield seismic tomograms and computed the corresponding seismicity rate. We found that high velocity anomalies grew with the increase of seismicity rates, and they switched to a shrinking tendency under low seismicity rates. Results of this study imply that seismicity rates increase with increasing stress concentration and decrease with decreasing stress concentration. This study highlights the value of utilizing passive seismic tomography for estimating stress evolution associated with the change of seismicity rates at underground mines. Our findings illuminate the applications of using mining-induced seismicity to assess stress redistribution associated with seismicity rates at hard-rock mines, providing insights into seismic hazards for deep mining.

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Velocity-Free MS/AE Source Location Method for Three-Dimensional Hole-Containing Structures

Cited by 124 publications

References 24 publications

Micro-Crack Mechanism in the Fracture Evolution of Saturated Granite and Enlightenment to the Precursors of Instability

Micro-Crack Mechanism in the Fracture Evolution of Saturated Granite and Enlightenment to the Precursors of Instability

Text Analysis Reveals Major Trends in Exploration Geophysics

Passive Seismic Imaging of Stress Evolution with Mining-Induced Seismicity at Hard-Rock Deep Mines

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