Abstract：High-pressure air blasting (HPAB) is one type of physical blasting techniques to increases the permeability of the coal seam by instantly releasing high-pressure air to impact the coal. In this paper, the experimental study on the HPAB of simulation coal is conducted using the self-developed HPAB experimental system. To reveal the propagation and attenuation law of stress wave, and the process and mechanism of coal damage-fracture under the action of HPAB, the ultrasonic velocity, strain and cracks propagation speed are tested. Based on the experimental results and the theory of damage fracture mechanics, it can be concluded that the stress wave waveform generated under the action of HPAB is the same as that generated under the action of explosive blasting. However, the peak stress of the HPAB stress wave is smaller than that of the explosive stress wave. Moreover, the action time and the pulse width of the HPAB stress wave are longer than that of the explosive stress wave, and the HPAB stress wave decays at a slower speed (α = 2-μ/(1-μ)). Under the tensile action of the HPAB stress wave, the initial radial cracks in coal are generated firstly, and the initial radial cracks propagate rapidly at 0.15-0.4 times the speed of the ultrasonic velocity. Subsequently, the initial radial cracks propagate steadily at 0.12-0.14 times the speed of the ultrasonic velocity with the combined effect of high-pressure air, the methane gas pressure, and the in-situ stress. Finally, the periodic original cracks, which are in the far area of the blasthole, slowly propagate in a small area with the combined effect of elastic stress wave, the methane gas pressure, the in-situ stress and the interaction between parallel original cracks.
Key words: Simulation coal; High-pressure air blasting (HPAB); Propagation and attenuation law of HPAB stress wave; Coal damage-fracture; Experimental study
褚怀保1,2，王昌1，杨小林1,2，严少洋1，魏海霞1，任志强1，陈真1，朱思源1. 煤体高压空气爆破模拟试验研究[J]. 振动与冲击, 2022, 41(20): 54-60.
CHU Huaibao1,2，WANG Chang1，YANG Xiaolin1,2，YAN Shaoyang1，WEI Haixia1，REN Zhiqiang1，CHEN Zhen1，ZHU Siyuan1. A simulation experimental study on high-pressure air blasting of coal. JOURNAL OF VIBRATION AND SHOCK, 2022, 41(20): 54-60.
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