1996 Fiscal Year Final Research Report Summary
Scaling laws of AE events in rocks
| Project/Area Number |
07651154
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
資源開発工学
|
|---|
| Research Institution | KYOTO UNIVERSITY (1996)
Nihon University Junior College (1995) |
|---|
Principal Investigator |
YANAGIDANI Takashi Kyoto Univ., RCEP DPRI,Associate Prof., 防災研究所, 助教授 (00259128)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
YOSHINO Takashi Toyo Univ., Engineering, Lecturer, 工学部, 講師 (60269496)
TSUKADA Kazuhiko Kyoto Univ., Engineering, Associate Prof., 大学院・工学研究科, 助教授 (10179971)
|
|---|
| Project Period (FY) |
1995 – 1996
|
| Keywords | Acoustic Emission / Scaling law / Power law |
|---|
| Research Abstract |
The frequency-magnitude distribution of AE events in rocks was found to obey the powerlaw, which is just the case of natural earthquakes. These conventional results, however, must be examined using more sophisticated measurement system, because they are concluded without observing actual waveforms, and the narrow dynamic range of monitoring system also limits the validity of these findings, In this study, we have tried to acquire the complete waveforms of AE events during the main fracture under uniaxial compression by newly developed monitoring system with wider dynamic range. The 6 preamplifiers (whose frequency response is from 1.5 kHz to 20 MHz) are combined to get dynamic range of 4^<1h> order (i.e. *2 mVpp-*2 Vpp referred to input). Four serial outputs of preamplifiers are digitized by high-speed AID converters (5 MS/s) with high resolution (12 bit). The digitized waveforms of AE events are stored within a long memory, which make it possible to analyze AE events up to 2 seconds in terms of complete waveforms. The frequency-magnitude distribution of AE events is observed to obey power law and to be self-similar in even wider amplitude range, which is consistent with conventional findings, On the other hand, other type of scaling law such as maximum amplitude vs. dominant frequency, which is clearly seen in the case of natural earthquakes, does not hold in the case of AE events. That means the similarity between nature earthquakes and AE events are very limited. The tears of scaling law in AE events are problematic and mysterious, and to solve this will lead to full understanding as to what is AE events.
|
