Master crack types and typical acoustic emission characteristics during rock failure

Abstract

Acoustic emission (AE) signals contain substantial information about the internal fracture characteristics of rocks and are useful for revealing the laws governing the release of energy stored therein. Reported here is the evolution of rock failure with different master crack types as investigated using Brazilian splitting tests (BSTs), direct shear tests (DSTs), and uniaxial compression tests (UCTs). The AE parameters and typical modes of each fracture type were obtained, and the energy release characteristics of each fracture mechanism were discussed. From the observed changes in the AE parameters, the rock fracture process exhibits characteristics of staged intensification. The scale and energy level of crack activity in the BSTs were significantly lower than those in the DSTs and UCTs. The proportion of tensile cracks in the BSTs was 65%–75%, while the proportions of shear cracks in the DSTs and UCTs were 75%–85% and 70%–75%, respectively. During the rock loading process under different conditions, failure was accompanied by an increased number of shear cracks. The amplitude, duration, and rise time of the AE signal from rock failure were larger when the failure was dominated by shear cracks rather than tensile ones, and most of the medium- and high-energy signals had medium to low frequencies. After calculating the proposed energy amplitude ratio, the energy release of shear cracks was found to exceed that of tensile cracks at the same fracture scale.

Study on the evolutionary characteristics of strain energy on crack propagation in coal and rock under bending load

“…The loading system used in the test is RLJW-2000 rock servo pressure testing machine. 27 Before formal loading, preload the sample to ensure full contact between the indenter and the sample. The contact line of the upper indenter is symmetrical in the center of the sample.…”

Effect of Chemical Corrosion on Rock Fracture Behavior in Coastal Deep Mines: Insights from Mechanical and Acoustic Characteristics

“…The AE signals released during the compression of granite specimens are closely associated with the formation and propagation of microcracks [44][45][46][47][48]. The characteristics of temporal AE sequences for granite specimens under different confining pressures are depicted in Figures 11-13 Combined with the stress-strain curves, it can be observed that the AE count characteristics of granite specimens under different immersion conditions are generally similar during the deformation and failure processes.…”

“…AE frequency domain characteristics can be used to analyze the fracture process and to identify fracture precursor information of rocks [44,45]. The evolution characteristics of the peak frequency distribution of granite specimens under different chemical corrosion conditions are shown in Figures 14-16.…”

Acoustic emission characteristic of sandstone and sandstone like material under multi-path loading

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