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| Influence of short delay time and bottom charge on blast-induced damage of rock mass in parallel cutting blasting |
| ZHOU Zilong, WANG Peiyu*, WU Shenggang, CAI Xin, CHEN Cuigang, YUAN Jifeng
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| (School of Resources and Safety Engineering, Central South University, Changsha 410083, Hunan, China) |
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Abstract To enhance rock fracture at the bottom of the cut cavity, a three-dimensional finite element model of parallel cutting blasting with small-diameter empty holes was developed. The effects of delay time and bottom charge on rock damage area and distribution characteristics during parallel cutting blasting were quantitatively analyzed. The results showed that in parallel cutting blasting with small-diameter empty holes，both the rock damage range and the fractal dimension of blast-induced fractures decreased nonlinearly with increasing distance from the free surface, resulting in poor fracturing effect at the cavity bottom. Short delay initiation was found to enhance rock fracturing at the middle and bottom parts of the rock cavity, with the damage area and fractal dimension of rock at bottom first increased and then decreased as the delay time increased from 0 ms to 3 ms, reaching optimal performance at 1 ms. The empty hole depth was extended and a bottom charge was added in the overd-rilled section of the empty holes to further intensify fracturing at the cavity bottom. On this basis, field tests were conducted, and a significant improvement in drift excavation performance was demonstrated, with the average borehole utilization rate increasing by 9.1%.
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Received: 20 March 2025
Published: 18 June 2025
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