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Liquid carbon dioxide phase change fracturing technology (LCPCFT) has been widely used in engineering blasting due to the advantage of no flames, and no toxic and harmful gas. However, few studies have been conducted on the acquisition of shock wave pressure and its loading characteristics, which are key parameters in fracturing. Referring to the CO2 in-situ fracturing technology, an indoor test system for shock wave pressure generated during LCPCFT has been built, with a protected polyvinylidene fluoride (PVDF) piezoelectric sensor. Then three verification experiments with different radial distances between the fracturing tube and test points were carried out on the test system, and in each experiment, four PVDF sensors as four test points were arranged with different axial distance from the detonating point to test the pressure distribution. The experimental results show that when the radial distance between the fracturing tube and test points is not too large (≤345 mm), the pressure generated during LCPCFT is approximately uniformly distributed within the axial length of the fracturing tube, but when it is relatively large (≈895 mm), the results between different test points are in a certain degree of dispersion. And finally, this paper uses the intraclass correlation coefficient (ICC) and coefficient of variation (CV) of peak pressure and impulse to process the test results to evaluate the reliability and stability of the test system. Evaluation results show that the test results are in good consistency. The test system in this paper has good stability and high reliability. The test system provides a useful tool for accurately obtaining the shock wave pressure, which is helpful for further research on LCPCFT.
Xing Haung; Qiyue Li; Xin’Ao Wei; Xiaoxiao Yang; Dayou Luo; Haideng Zeng; Hongwei Wang. Indoor Test System for Liquid CO2 Phase Change Shock Wave Pressure with PVDF Sensors. Sensors 2020, 20, 2395 .
AMA StyleXing Haung, Qiyue Li, Xin’Ao Wei, Xiaoxiao Yang, Dayou Luo, Haideng Zeng, Hongwei Wang. Indoor Test System for Liquid CO2 Phase Change Shock Wave Pressure with PVDF Sensors. Sensors. 2020; 20 (8):2395.
Chicago/Turabian StyleXing Haung; Qiyue Li; Xin’Ao Wei; Xiaoxiao Yang; Dayou Luo; Haideng Zeng; Hongwei Wang. 2020. "Indoor Test System for Liquid CO2 Phase Change Shock Wave Pressure with PVDF Sensors." Sensors 20, no. 8: 2395.
Safely and high-efficiently breaking rock is of practical significance. In some engineering, explosive blasting may be restricted for its side effects. Traditional non-explosive methods like demolition agent and rock breaking machine are generally time-consuming. Therefore, this study proposes a novel liquid carbon dioxide rock-breaking technology and designs the relative device. The effectiveness, safety and high-efficiency of the proposed technology are investigated by shock pressure test, vibration site test and field rock breaking experiment. The experimental results show that the duration of the monitoring shock pressure is around 1500 μs. The shock pressure signal of liquid carbon dioxide tube breaking in free condition contains four stages, namely, increasing exponentially, decreasing oscillatory, stabilization, and negative pressure stage. As pressure sensor is set at 850 mm from the test tube radially, the shock pressure monitored increases to the maximum value of 115.7 kPa within 6 μs. During the liquid carbon dioxide rock breaking, the vertical component of the peak particle velocity of vibration is 173 mm/s, 85 mm/s and 35 mm/s along distance at 1.5 m, 2.5 m and 3.5 m from the tube, respectively. The Fourier power spectra results show that about 85% energy distributes at 6–60 Hz. The vibration caused by the novel technology can meet the requirement of mainstream blasting safety criteria better than that of explosive blasting. Finally, the technology is successfully applied in rock excavation at a metro station construction site. The proposed liquid carbon dioxide rock-breaking technology is preliminarily demonstrated to be safer than explosive blasting and more efficient than traditional non-explosive techniques.
Qi-Yue Li; Guan Chen; Da-You Luo; Hai-Peng Ma; Yong Liu. An experimental study of a novel liquid carbon dioxide rock-breaking technology. International Journal of Rock Mechanics and Mining Sciences 2020, 128, 104244 .
AMA StyleQi-Yue Li, Guan Chen, Da-You Luo, Hai-Peng Ma, Yong Liu. An experimental study of a novel liquid carbon dioxide rock-breaking technology. International Journal of Rock Mechanics and Mining Sciences. 2020; 128 ():104244.
Chicago/Turabian StyleQi-Yue Li; Guan Chen; Da-You Luo; Hai-Peng Ma; Yong Liu. 2020. "An experimental study of a novel liquid carbon dioxide rock-breaking technology." International Journal of Rock Mechanics and Mining Sciences 128, no. : 104244.