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Shock and Vibration
Volume 2017, Article ID 5387459, 13 pages
https://doi.org/10.1155/2017/5387459
Research Article

Acoustic Emission Characteristics and Failure Mechanism of Fractured Rock under Different Loading Rates

1Shandong Provincial Key Laboratory of Civil Engineering Disaster Prevention and Mitigation, Shandong University of Science and Technology, Qingdao 266590, China
2State Key Laboratory of Mining Disaster Prevention and Control Co-Founded by Shandong Province and the Ministry of Science and Technology, Shandong University of Science and Technology, Qingdao 266590, China
3Research Center of Geotechnical and Structural Engineering, Shandong University, Jinan 250061, China
4State Key Laboratory of Structural Analysis for Industrial Equipment, Dalian University of Technology, Dalian 116024, China
5College of Pipeline and Civil Engineering, China University of Petroleum, Qingdao 266555, China

Correspondence should be addressed to Gang Wang; moc.liamg@0111gnaggnaw

Received 13 June 2017; Revised 21 August 2017; Accepted 12 September 2017; Published 15 October 2017

Academic Editor: M. I. Herreros

Copyright © 2017 Yongzheng Zhang et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

To study the loading rate dependence of acoustic emissions and the failure mechanism of fractured rock, biaxial compression tests performed on granite were numerically simulated using the bonded particle model in Particle Flow Code (PFC). Uniaxial tests on a sample containing a single open fracture were simulated under different loading rates ranging from 0.005 to 0.5 m/s. Our results demonstrate the following. (1) The overall trends of stress and strain changes are not affected by the loading rate; the loading rate only affects the strain required to reach each stage. (2) The strain energy rate and acoustic emission (AE) events are affected by the loading rate in fractured rock. With an increase in the loading rate, AE events and the strain energy rate initially increase and then decrease, forming a fluctuating trend. (3) Under an external load, the particles within a specimen are constantly squeezed, rotated, and displaced. This process is accompanied by energy dissipation via the production of internal tensile and shear cracks; their propagation and coalescence result in the formation of a macroscopic rupture zone.