Ishida / Labuz Microcracking in Rock as Acoustic Emission

1. Auflage 2016
ISBN: 978-1-136-73210-2
Verlag: Taylor & Francis
Format: PDF
Kopierschutz: 0 - No protection

E-Book, Englisch, 250 Seiten

Reihe: Geomechanics Research

Rock stress and rock damaging are some of the main obstacles encountered when designing and constructing engineering projects with rock. This book will provide a basis to interpret acoustic emission (AE) as damage processes in stressed rock, with applications to stress measurements, size effects, source mechanisms, and fracture mechanics. The nature of rock will be described as a crystalline solid with voids in the form of small cracks and pores called damage, and AE will be explained as energy released as a result of increase in damage. Basic features of an AE monitoring system will be covered, with some background on the sensor, pre-amplifier, and data acquisition. Waveform analyses will include source locations through a geometric interpretation and a numerical algorithm, which will be available through the authors’ web sites. Fault plane solutions and moment tensor analysis will be presented for a quantitative evaluation of micromechanisms of rock failure under tension and shear. Several examples of AE monitoring will include both lab and field applications ranging from element testing to hydraulic fracturing. Intended for geologists, geophysicists and mining, petroleum and civil engineers dealing with rock stress and rock damage processes.

Autoren/Hrsg.

Ishida, Tsuyoshi

Labuz, Joseph

Fachgebiete

• Geowissenschaften Geologie Geologie
• Technische Wissenschaften Bauingenieurwesen Bauingenieurwesen
• Geowissenschaften Geologie Geophysik

Inhaltsverzeichnis

1. Introduction
1.1. Nature of rock
1.2. Damage and acoustic emission (AE)
1.3. Basic concepts of AE

2. Monitoring AE
2.1. Laboratory studies
2.1.1. AE sensor, pre-amplifier
2.1.2. Electric noise and filters
2.2 Field studies
2.2.1. Sampling time and monitoring frequency
2.2.2. Attenuation and resolution of amplitude
2.3 AE waveform
2.3.1. Trigger time, duration, and maximum amplitude
2.3.2. Frequency analysis
2.3.3. AE count rate
2.4. Application: stress measurement and Kaiser effect

3. Source location of AE
3.1. Problem statement and direct method
3.2. Lattice approach: trial-and-error method
3.3. Iterative approach: least squares method
3.4. Special cases Method of source location under a
3.4.1. P-wave anisotropy
3.4.2. Constraint condition
3.4.3. P- and S-wave arrival times
3.4.4. Propagation paths and sensor positions
3.5. Application: fracture initiation

4. Source mechanism of AE
4.1. Mechanics of microcracking
4.2. Fault plane solution and stereographic projection
4.3. Moment tensor analysis
4.3.1. Displacement discontinuity model
4.3.1.2. Sensor calibration
4.4. Application: shear banding

5. Rock mechanics issues
5.1. Hydraulic fracturing
5.1.1. Laboratory experiments
5.1.2. Field studies
5.2. Hot dry rock geothermal project
5.3. In situ stress measurement
5.4. Heater test
5.5. Underground powerhouse

6. Concluding remarks
6.1. Numerical modeling
6.2. Structural health monitoring