Seismic instruments: article

P.A. Kaznacheev
Z.Y. Maibuk
A.V. Ponomarev
Schmidt Institute of Physics of the Earth of the Russian Academy of Sciences
Journal: Seismic instruments
Tome: 55
Number: 1
Year: 2019
Pages: 29-45
UDK: 550.83+620.179
DOI: 10.21455/si2019.1-2
Keywords: rock, acoustic emission, thermoemission memory effect, laboratory setup, hardware development
Аnnotation: Thermal stimulated rock failure is researched actively during more than 30 years for fundamental and applied problems solving. At the same time, there are methodological specifics that complicate to accessing of data about thermal failure growth in comparison with mechanical failure. In paper, three main problems are examined. For its solving, the improved laboratory setup is developed. First problem is fewness of thermoacoustic emission impulses. The developed setup has acoustic waveguide of the little length, as compared with works of other authors, firstly. For preventing of overheating of acoustic emission sensor, outer waveguide end has heat sink with forced cooling. Secondly, the setup has layer of melted indium between specimen and inner waveguide end. Therefore, energy loss of acoustic emission impulses is reduced substantially. Second problem is thermal conditions difference of heating and cooling, namely difference of temperature gradient direction. The setup construction saves direction of temperature gradient on cooling nearly identical with heating. Third problem is generation of acoustic and electromagnetic disturbances by traditional heating control system with current commutation. It’s proposed to use piecewise-linear (step-by-step) heating power control. In this case, very few disturbances are observed, only in instant of heating power jump. Experiments with few tens rock specimens show productivity and effectiveness of the setup and the technique.