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Acoustic Emission at Wedge Indentation Fracture in Quasi-Brittle Materials

Published online by Cambridge University Press:  05 May 2011

L. H. Chen ,
K. C. Huang  and
Y. C. Chen
L. H. Chen*
Affiliation:
Department of Civil Engineering, National Taipei University of Technology, Taipei, Taiwan 10608, R.O.C.
K. C. Huang*
Affiliation:
Department of Construction Engineering, National Taiwan University of Science and Technology, Taipei, Taiwan 10672, R.O.C.
Y. C. Chen*
Affiliation:
Department of Construction Engineering, National Taiwan University of Science and Technology, Taipei, Taiwan 10672, R.O.C.
*
*Assistant Professor
**Ph.D., corresponding author
***Professor
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Abstract

To improve the safety and automation of mechanical excavation methods used in tunnels, this present report studied the behavior of rock materials indented by a single cutter, based on the theory of indentation fracture mechanics. The development of microcracks during the indentation process and the correlation between microcracks and macrocracks was investigated using the nondestructive technique of acoustic emission. Microseismic activity of the microcracks received by the acoustic emission (AE) technique was used to interpret and represent the initiation and propagation of macrocracks. As the wedge angle increased, the maximum indentation force increased, but the nominal indentation pressure and the destructive indentation depth decreased. On the other hand, the direction of macrocrack propagation did not significantly change with the various wedge angles. Furthermore, the localization occurred earlier and the dimensionless radius of the elasto-plastic interface decreased with increased wedge angle. In addition, the dimensionless radius of the elasto-plastic interface obtained by the experiment was consistent with closed-form analytical solutions.

Keywords

Acoustic emission (AE)Indentation fractureCavity expansion model (CEM)Wedge angleContact mechanics.
Type
Articles
Information
Journal of Mechanics , Volume 25 , Issue 2 , June 2009 , pp. 213 - 223
Copyright
Copyright © The Society of Theoretical and Applied Mechanics, R.O.C. 2009

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