Rock Thickness Measurement by Using Self-Excited Acoustical System

Authors: JanuszKwaśniewski, IreneuszDominik, KrzysztofLalik

Abstract:

The knowledge about rock layers thickness,especially above drilled mining pavements is crucial for workers safety. The measuring systems used nowadays are generally imperfect and there is a strong demand for improvement. The application of a new type of a measurement system called Self-excited Acoustical System is presentedin the paper. The system was applied until now to monitor stress changes in metal and concrete constructions. The change in measurement methodology resulted in possibility of measuring the thickness of the rocks above the tunnels as well as thickness of a singular rocklayer. The idea is to find two resonance frequencies of the self-exited system,which consists of a vibration exciter and vibration receiver placed at a distance, which are coupled with a proper power amplifier, and which operate in a closed loop with a positive feedback. The resonance with the higher amplitude determines thickness of the whole rock, whereas the lower amplitude resonance indicates thickness of a singular layer. The results of the laboratory tests conducted on a group of different rock materials are also presented.

Keywords: Autooscillator, non-destructive testing, rock thickness measurement.

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1091016

References:

[1] A. H.Onur, S.Bakraç and D.Karakuş,Ultrasonic Waves in Mining Application(Book style) ed. A. A. dos Santos, ISBN 978-953-51-0201-4, 2012.
[2] T.A. Melby, "Sprayed Concrete for Rock Support,” MBT International Underground Construction Group. 1994. 186 p.
[3] P. Guevremont,F.P. Hassani, "Using NDT for Thickness Measurement of Shotcrete Rock Support Systems in Underground Mines,”AIP Conference Proceedings, 2000, Vol. 509 Issue 1, p1701.
[4] W. J. Johannes, W. Jacoby, P. L. Smilde,Gravity Interpretation: Fundamentals and Application of Gravity Inversion. Springer, 2009. ISBN 978-3-540-85328-2.
[5] R. L. Chufo, "An Electromagnetic Noncontacting Sensor for Thickness Measurement in a Dispersive Media,” U.S. Bureau of Mines, Pittsburgh, Pennsylvania. Proc AIAA/NASA Conference on Intelligent Robots in Field, Factory, Service, and Space, 1994, Jon D. Erickson, Houston, TX 1:190-194
[6] J. Kwaśniewski, I. Dominik, J. Konieczny, K. Lalik., A. Sakeb, Application of Self-Excited Acoustical System for Stress Changes Measurement in Sandstone Bar, Journal of Theoretical and Applied Mechanics ; ISSN 1429-2955. —vol. 49 no. 4, 2011
[7] J. Kwaśniewski, I. Dominik, K. Lalik, Application of Self-Oscillating System for Stress Measurement in Metal,Journal of Vibroengineering; ISSN 1392-8716. — vol. 14, 2012
[8] V.I. Babitsky, V.K. Astashev, A.N. Kalashnikov: AutoresonantControl Of Nonlinear Mode in Ultrasonic Transducer for Machining Applications, ISSN 0041-624X, Ultrasonics,. 2004
[9] Weaver R. L., Lobkis O. I., Yamilov A., Entrainment and Stimulated Emission of Ultrasonic Piezoelectric Auto-Oscillators, Acoustical Society of America, 2007
[10] S. Poklonskyi, Ways to Improve the Definition of SoilsDeformationCharacteristics in LaboratoryConditions, Advances in Soil Mechanics and Geotechnical Engineering, Volume 2: Proceedings of the 5th International Young Geotechnical Engineers' Conference, 2013