Fracture evolution during rockburst under true-triaxial loading using acoustic emission monitoring
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ORIGINAL PAPER
Fracture evolution during rockburst under true-triaxial loading using acoustic emission monitoring Shaobin Zhai 1,2 & Guoshao Su 1
&
Shunde Yin 2 & Sizhou Yan 1 & Zhengfu Wang 1 & Liubin Yan 1
Received: 5 November 2019 / Accepted: 20 May 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract This paper investigates the fracture evolution during rockbursts of granodiorite and basalt that appeared to be representatives of two different rockburst modes under true-triaxial loading using acoustic emission (AE) analysis. In the experiments, with the macroscale ejection and failure features captured and presented by the high-speed video imaging and failed specimens, the inside micro- or meso-scale fracturing was detected and analyzed in detail by AE in terms of intensity, temporal-spatial distribution, and mechanism. The experimental results and AE analyses show that the fracture evolution during rockburst (particularly in granodiorite) exhibits hierarchical characteristics: during early loading, small local microfractures developed progressively and stably mainly by tension and clustered preliminarily; around and after the point of the crack damage stress, large-scale fractures developed and coalesced rapidly and unstably with increasing shear mechanism, and nucleation zones significantly developed; upon rockburst failure, rocks near the free face buckled or fractured and ejected rapidly, and shear ruptures suddenly ran through. The findings help facilitate the rockburst prediction and control. Keywords Rockburst . True-triaxial test . Fracture evolution . Acoustic emission
Introduction As mining and rock engineering migrates to deeper grounds, rockburst, a typical dynamical failure of rocks near the excavation boundary accompanied by violent ejection of rock fragments, frequently occurs and severely threatens mining and construction safety (Cook 1965b; Hedley 1992; Ortlepp and Stacey 1994; Ortlepp 2001; Zhang et al. 2012; Cai and Kaiser 2018; Feng et al. 2018). It has been widely recognized that rockburst is a complex phenomenon associated with multiple factors and multiscale fractures and that the fracture evolution and failure mechanism of rockburst should be further detected to proactively and scientifically predict and prevent rockburst. Over the years, many research works on rockburst failure
* Guoshao Su [email protected] 1
Key Laboratory of Disaster Prevention and Structural Safety of Ministry of Education, Guangxi Key Laboratory of Disaster Prevention and Engineering Safety, School of Civil and Architecture Engineering, Guangxi University, Nanning 530004, China
2
Department of Civil and Environmental Engineering, University of Waterloo, Waterloo, ON N2L 3G1, Canada
investigation (Cook 1965a; Zubelewicz and Mróz 1983; Vardoulakis 1984; Linkov 1996; He et al. 2010; Jiang et al. 2010; Manouchehrian and Cai 2015; Xiao et al. 2016; Li et al. 2017; Su et al. 2017a, b; Gong et al. 2018, 2019) have demonstrated that the controlled laboratory experiments that can reproduce
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