Measurement and Stress Response Analysis of Complete History of Blast-Induced Wall Pressure for Boreholes: A Case with Air-Deck Charge.
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| Title: | Measurement and Stress Response Analysis of Complete History of Blast-Induced Wall Pressure for Boreholes: A Case with Air-Deck Charge. |
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| Authors: | Li, Qiyue1 (AUTHOR), Wei, Xinao1 (AUTHOR) xinaqwei@gmail.com, Li, Xibing1 (AUTHOR), Liu, Kai1 (AUTHOR), Dong, Longjun1 (AUTHOR), Tao, Ming1 (AUTHOR), Li, Haiqian1 (AUTHOR) |
| Source: | Rock Mechanics & Rock Engineering. Nov2024, Vol. 57 Issue 11, p9429-9443. 15p. |
| Subjects: | Gas explosions, Strains & stresses (Mechanics), Polyvinylidene fluoride, Coaxial cables, Shock waves, Blast effect |
| Abstract: | The blast pressure acting on the borehole wall is the basis of the dynamic analysis of rock blasting. The history of blast-induced borehole wall pressure (BWP) is difficult to measure owing to the complex interaction between the blasting load and the borehole wall, and the limitations of the general test system. In this work, the complete history of BWP under air-deck charge was measured for the first time, and the stress-response process was analyzed. PVDF (polyvinylidene fluoride) gages and a charge mode for the test circuit were employed. To improve the testing accuracy, the matching relationships among the parallel capacitor, the equivalent capacitance of PVDF gages, and the parasitic capacitance of the coaxial cable were effectively addressed. The experimental data within the span of 0–0.65 m from the explosive cartridge center show that there are two obvious peaks in the complete history of BWP, the first is a μs-level air shockwave load, followed by a ms-level explosion gas load. The peak of BWP is dominated by the peak of explosion gas (Pg) within the scope of about 0–0.35 m from the explosive cartridge center, while is mainly determined by the peak of air shockwave (Ps) in a farther range. The specific impulse distribution suggests that the explosion energy is mainly consumed in the area within the range of about 0–0.25 m from the explosive cartridge center. The strain rate in the borehole wall induced by air shockwave demonstrates a dynamic response (range of 131.9 ~ 2922.6 s−1), while indicating a quasi-dynamic loading (range of 0.1 ~ 2.1 s−1) when induced by the explosion gas. The findings contribute to expanding the understanding of the stress characteristics of the air shock wave and explosion gas and provide accurate initial loads for numerical simulation related to rock blasting of non-fluid–solid coupling. Highlights: The complete history of borehole wall pressure under air-deck charge was accurately measured by solving the capacitance matching in the test circuit for charge mode. The entire stress response process of the borehole wall rock is revealed. The specific impulse distribution of air shock wave and explosion gas along the borehole axis is obtained. The stress characteristics of borehole wall induced by air shockwave and explosion gas are compared. [ABSTRACT FROM AUTHOR] |
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| Abstract: | The blast pressure acting on the borehole wall is the basis of the dynamic analysis of rock blasting. The history of blast-induced borehole wall pressure (BWP) is difficult to measure owing to the complex interaction between the blasting load and the borehole wall, and the limitations of the general test system. In this work, the complete history of BWP under air-deck charge was measured for the first time, and the stress-response process was analyzed. PVDF (polyvinylidene fluoride) gages and a charge mode for the test circuit were employed. To improve the testing accuracy, the matching relationships among the parallel capacitor, the equivalent capacitance of PVDF gages, and the parasitic capacitance of the coaxial cable were effectively addressed. The experimental data within the span of 0–0.65 m from the explosive cartridge center show that there are two obvious peaks in the complete history of BWP, the first is a μs-level air shockwave load, followed by a ms-level explosion gas load. The peak of BWP is dominated by the peak of explosion gas (Pg) within the scope of about 0–0.35 m from the explosive cartridge center, while is mainly determined by the peak of air shockwave (Ps) in a farther range. The specific impulse distribution suggests that the explosion energy is mainly consumed in the area within the range of about 0–0.25 m from the explosive cartridge center. The strain rate in the borehole wall induced by air shockwave demonstrates a dynamic response (range of 131.9 ~ 2922.6 s−1), while indicating a quasi-dynamic loading (range of 0.1 ~ 2.1 s−1) when induced by the explosion gas. The findings contribute to expanding the understanding of the stress characteristics of the air shock wave and explosion gas and provide accurate initial loads for numerical simulation related to rock blasting of non-fluid–solid coupling. Highlights: The complete history of borehole wall pressure under air-deck charge was accurately measured by solving the capacitance matching in the test circuit for charge mode. The entire stress response process of the borehole wall rock is revealed. The specific impulse distribution of air shock wave and explosion gas along the borehole axis is obtained. The stress characteristics of borehole wall induced by air shockwave and explosion gas are compared. [ABSTRACT FROM AUTHOR] |
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| ISSN: | 07232632 |
| DOI: | 10.1007/s00603-024-04033-y |
