期刊
MATHEMATICS
卷 10, 期 3, 页码 -出版社
MDPI
DOI: 10.3390/math10030451
关键词
true triaxial compression test; acoustic emission; b value
类别
资金
- National Science Foundation for Excellent Young Scholars of China [51822407]
- National Natural Science Foundation of China [51774326, 51504288]
- Natural Science Foundation for Distinguished Young Scholars of Hunan Province, China [2018JJ1037]
- Huxiang Young Talents Plan of Hunan Province, China [2018RS3001]
- open fund of Hebei Mining Development and Safety Technology Laboratory [2016kykf03]
- open fund of Mining Disaster Prevention and Control Ministry Key Laboratory at Shandong University of Science and Technology [MDPC201917]
The b value of acoustic emission is an important parameter for predicting rock fractures. This study analyzed the changes in b value during rock failure and investigated the characteristics of acoustic emission events. The results showed that b value calculated using the average amplitude had higher accuracy, and an interval of event counts of 200 was suggested for b value calculations. The study also found that the b value decreased before fracture and decreased with increasing confining pressure.
The acoustic emission b value is an important and widely used parameter for the early prediction of rock fractures. In this study, five groups of true triaxial compression tests were conducted on granite specimens to analyze changes in b value during the process of rock failure, and to investigate the b value characteristics of acoustic emission events. First, the acoustic emission events that simultaneously triggered at least four sensors were located using P-wave arrivals and sensor coordinates. Then, considering various intervals of acoustic emission event counts, stress magnitude, and stress proportion, b values were calculated using the values of the maximum amplitude, average amplitude, maximum absolute energy, and average absolute energy of the acoustic emission events. In addition, the goodness of the fitting curves was used to evaluate the fitting reliability of the b values. The results indicated higher accuracy of b value when calculated using the average amplitude setting for intervals of acoustic emission event counts of 200 or greater, stress magnitude of 20 MPa or greater, and stress proportion of 10% or greater. Moreover, the interval of event counts of 200 is suggested as a window parameter for b value calculations, and the b values are observed to exhibit a decreasing trend before fracture for more than 80% of the specimens. Furthermore, the b value tends to decrease with an increase in confining pressure. Thus, the b value can be used as an indicator for validating the stress concentration area, including magnitudes and accumulative probability density distribution of events, which is a beneficial complement to clarifying precursor information of rock mass instability.
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