Abstract
Rock breakage is inevitable for creating openings in underground engineering operations. Ultrasonic vibration has been attracting extensive attention for such a practice considering its outstanding performance in rock breakage. In order to understand the fundamental failure mechanism of rocks subjected to ultrasonic vibrations, based on P-wave monitoring and the direct current electric method, we captured the evolution of the failure process of the red sandstone. In addition, we fundamentally analyse the failure mechanisms of the red sandstone using numerical simulation and microscopy scans. It was found that extensive fractures were initiated due to the ultrasonic vibration and the fractures propagated downwards forming a conical shape. The apparent resistivity became as high as 320000 Ω being 16 times the initial resistivity. The fracture propagated downwards as deep as 41 mm. The maximum damage parameter on the testing sample could be as high as 0.68, and it completely failed after 140 s of ultrasonic vibration duration. As a result of numerical simulation, it was found that the microfractures and pores in the testing sample were activated due to the stress wave resulting from the ultrasonic vibration leading to the fracture propagation and eventually complete failure. Through comparing the performance of uniaxial compressive loading and ultrasonic vibration techniques in rock damage, it was concluded the latter has a much higher capacity and competence in rock breakage.
Highlights
Jiyao Wang,1 Xufeng Wang,1 Xuyang Chen,1 Liang Chen,1,2 Zhanbiao Yang,3,4 Zechao Chang,1 Lei Zhang,1 and Zhijun Niu 1
As opposed to the aforementioned studies, in this research, we examined the fracture propagation in the red sandstone due to ultrasonic vibration damage followed by further analysing the failure mechanism in the rock breakage. e scope of the paper is in Section 2, where we introduced research methodologies and sample preparation as well as the testing facility; in Section 3, we presented our testing results along with data analysis; in Section 4, we investigated the failure mechanism of the red sandstone subject to ultrasonic vibration damage and in Section 5, we made a remarkable conclusion
Due to the current study of ultrasonic vibration excitation, broken rock is still in its infancy, so this article from the perspective of the abovementioned test results of ultrasonic vibration excitation, the failure mechanism of the rock are discussed for the failure mechanism in the process of rock specimen broken for further exploration, with the method of numerical simulation to simulate the process of specimen damage analysis
Summary
E core facilities in this research are the ultrasonic vibration component (see Figure 1) and direct current electricity monitor (see Figure 2). Electrical resistivity is a key geophysical parameter for rocks It can be obtained by the direct current electrical method and used to indicate the internal failure or fractures in the rock. Coli et al [24] successfully captured the fractures in the excavation surface in underground operations based on their research in the correlation between the rock pore size and hydraulic conductivity as well as electrical resistivity. As the ultrasonic vibration being generated longer, the area of the damage on the surface of the rock specimen increased and so did the length and the width of the fractures in the rock.
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