Amplitude-Frequency Analysis of Signals of Acoustic Emission from Granite Fractured at Elevated Temperatures

• Published in: Journal of engineering physics and thermophysics 2015-05, Vol.88 (3), p.786-790
• Main Authors: Shcherbakov, I. P., Chmel′, A. E.
• Format: Article
• Language: English
• Subjects: Acoustic emission testing; Analysis; Classical Mechanics; Complex Systems; Engineering; Engineering Thermodynamics; Heat and Mass Transfer; Industrial Chemistry/Chemical Engineering; Radioactive wastes; Thermodynamics
• ISSN: 1062-0125; 1573-871X
• DOI: 10.1007/s10891-015-1252-0

The problem of stability of underground structures serving to store radioactive waste, to gasify carbon, and to utilize geothermal energy is associated with the action of elevated temperatures and pressures. The acoustic-emission method makes it possible to monitor the accumulation of microcracks arising in stress fields of both thermal and mechanical origin. In this report, the authors give results of a laboratory investigation into the acoustic emission from granite subjected to impact fracture at temperatures of up to 600°C. An amplitude-frequency analysis of acousticemission signals has enabled the authors to evaluate the dimension of the arising microcracks and to determine their character (intergranular or intragranular). It has been shown that intergranular faults on the boundaries between identical minerals predominate at room temperature (purely mechanical action); at a temperature of 300°C (impact plus thermoelastic stresses), there also appear cracks on the quartz–feldspar boundaries; finally, at temperatures of 500–600°C, it is intragranular faults that predominate in feldspar. The dimensions of the above three types of microcracks are approximately 2, 0.8, and 0.3 mm respectively.