Frequency Characteristics of Acoustic Emissions Induced by Crack Propagation in Rock Tensile Fracture

Excerpt

Rocks are riddled with a large number of pre-existing micro-cracks (Ashby 1986; Yu and Feng 1995), which have significant influences on the strength, deformation, and rupture modes of rocks (Li et al. 2020). The initiation, propagation, and coalescence of micro-cracks inside stressed rocks may result in rock failure accompanied by the release and propagation of elastic waves in rocks, namely acoustic emission (AE). The generated AE signals inside rocks carry sufficient information on the released energy and can be used to reveal internal fracture characteristics and damage degree of rocks. AE monitoring technique can detect and record these vibration signals and reveal the local fracture characteristics (e.g., location, time, magnitude, fracture type) using various inversion strategies, which has widely applied in rock mechanics (Lavrov 2003; Prikry et al. 2003; Liu et al. 2015; Li et al. 2019; Wei et al. 2016). Moreover, previous studies have further extensively reported the strong relationship between AE and micro-seismic/seismic signals although the signal frequency scale and the fracture source dimension are significantly different (Benson et al. 2010; Benson et al. 2008; Burlini and Toro 2008), and indicated the potential values of AE signals for understanding rock fracture features (Lu et al. 2013, 2015). Therefore, reasonable and adequate interpretations of AE signals are vital in rock mechanics. …