Abstract
In order to explore the specimen failure characteristics during rock‐burst under different gradient stress conditions, in this paper, a novel experimental technique was proposed; a common series of tests under two gradient stress paths were conducted on rock similar material specimens using the true‐triaxial gradient and hydraulic‐pneumatic combined test apparatus. And plaster was used as the rock similar material. In the experimental process, several rock‐burst debris with area sizes of 100 mm2 were collected, and the fractal dimensions of typical detrital section crystal contours were analyzed and calculated using a scanning electron microscopy (SEM) method. The results showed that the specimens’ failure characteristics which had been induced by the two gradient stress processes were various. Also, the mesoscopic morphology of the rock‐burst detrital section had effectively reflected its macroscopic failure characteristics. It was found that the fractal dimensions of the crystal contours of the specimen’s detrital section had fractal characteristics, and the box‐counting dimension based on the SEM image could quantitatively describe the rock‐burst failure characteristics. Furthermore, under the same magnification, the fractal dimensions of the crystal contours of the splitting failures were found to be relatively smaller than those of the shearing failures.
Highlights
At the present time, with the gradual shortages in shallow mineral resources of the Earth, the annual global demand resource gap has increased, and the mining of mineral resources has gradually developed to deeper underground spaces. e occurrence environments of deep rock masses are extremely complex, and the stress concentrations in the surrounding rock of deep mining operation often lead to the sudden release of stored elastic energy after excavation activities, which subsequently result in rock-burst disasters [1]
Researchers usually use scanning electron microscopy (SEM) to determine the mechanical properties of rock masses in order to reveal the relationship between the mesoscopic morphology of the rock and the failure process
It was found in this study that the mesoscopic morphology of the detrital sections had accurately reflected the macroscopic failures of the rock-burst, which indicated that the stress loading modes had affected the failure modes of the specimens to some extent. erefore, the mesoscopic morphology of the detrital sections had characterized the macroscopic failures of the rock-burst and had reflected the incubation processes of the rockburst to a certain extent
Summary
With the gradual shortages in shallow mineral resources of the Earth, the annual global demand resource gap has increased, and the mining of mineral resources has gradually developed to deeper underground spaces. e occurrence environments of deep rock masses are extremely complex, and the stress concentrations in the surrounding rock of deep mining operation often lead to the sudden release of stored elastic energy after excavation activities, which subsequently result in rock-burst disasters [1]. Ng et al [7,8,9] processed the scanning images of research material using an electron microscope and established a model to predict crack growth In another related study, Zhang et al [10] detected the microstructures and mineral compositions of different. E application of SEM to the study of rock-burst mesostructure will potentially be helpful in increasing the understanding of the failure mechanisms related to rock-burst phenomena. By further combining the results with MATLAB software calculations, it was determined in this study that a debris fractal rule had existed under the different rock-burst failure modes in the cross sections of the specimens. E results of this study have potentially important theoretical significance for deepening the understanding of rock fracture characteristics and the influencing factors of rock-burst phenomena in surrounding rock masses during excavation activities By further combining the results with MATLAB software calculations, it was determined in this study that a debris fractal rule had existed under the different rock-burst failure modes in the cross sections of the specimens. e results of this study have potentially important theoretical significance for deepening the understanding of rock fracture characteristics and the influencing factors of rock-burst phenomena in surrounding rock masses during excavation activities
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