Multi-scale effect of acoustic emission characteristics of 3D rock damage

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ORIGINAL PAPER

Multi-scale effect of acoustic emission characteristics of 3D rock damage Wan-rong Liu 1 & Jian-kang Liu 2,3 & Chun Zhu 4 Received: 22 August 2018 / Accepted: 3 October 2019 # Saudi Society for Geosciences 2019

Abstract Scale effect and acoustic emission characteristics of rock damage are two important topics in rock engineering research. In this paper, considering different rock scales and establishing the 3D numerical rock models by means of PFC software platform firstly, the mechanical properties and acoustic emission characteristics were studied. Finally, based on the acoustic emission, characteristic discussed the damage evolution law of the rock models. The research result shows that the multi-scale mainly affects the peak strength, peak strain, and elastic modulus of the mechanic properties, affects the maximum acoustic emission event number, strain range of serious acoustic emission events of the acoustic emission characteristics, affects the damage rapid increase and damage failure stages of the damage evolution process. The stress-strain curves, acoustic emission events curves, and damage variable curves can be divided into three stages and different scales have different effect on these stages. Keywords Rock . Multi-scale . PFC . Mechanical properties . Acoustic emission . Damage

Introduction Scale effect is that the physical and mechanical properties of materials are not constant but vary with the size of material (Guo et al. 2002). Scale effect is widely found in defective materials such as rock and concrete (Zaytsev et al. 2017; SÅ‚owik and Smarzewski 2012). At present, there are many researches on the scale effect of mechanical properties of rock materials. In 1980, Heuze (1980) studied the scale effect in the Responsible Editor: Murat Karakus * Jian-kang Liu [email protected] Chun Zhu [email protected] 1

Liaocheng University, Liaocheng 252059, China

2

State 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

3

School of Engineering, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki, Japan

4

College of Construction Engineering, Jilin University, Changchun 130026, China

determination of rock mass strength and deformability. The results show that the scatter of the test results of the laboratory size samples is higher than the test results of the field size samples, and no reasonable procedure has been established to extrapolate the small size test results to the scale required for rock structure design. In 1992, Cuisiat and Haimson (1992) investigated the scale effects of rock mass stress measurement. It is concluded that in continuum mechanics, the stress is defined at a certain point and therefore should not involve any scale dependence. However, the solutions obtained in stress measurements are biased due to the natural scale dependence in the rock mass response. In addition, in the indirect stress measurement method, the stres