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| Optimization on the over/under-excavation of flat and super-large cross-section tunnel with drill and blast method |
| TIAN Ruiduan1, MO Guanwang2*, LI Xiang2
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1. Shanghai Tunnel Engineering Co., Ltd., Shanghai 200032, China;
2. School of Civil Engineering, SunYat-Sen University, Zhuhai 519082, Guangdong, China |
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Abstract To optimize and control the over/under-excavation phenomena observed in the excavation of flat and super-large cross-section tunnels using the drill and blast method. A highway tunnel served as a case study, where numerical models for tunnel sections with grade Ⅲ and Ⅳ surrounding rock were established. The blasting process of the tunnel cross-section was replicated, and field-measured data were utilized to validate the numerical models. Analyses were performed on the variations in blast damage nephograms, blast profiles, maximum and average over/under-excavation distances, and over-excavation areas across different blasting schemes. These analyses quantified the impact of varying peripheral and cut hole spacings, as well as the charge quantities in blast holes, on the over/under-excavation during tunnel blasting. Subsequent to these analyses, the blasting schemes were optimized. By integrating numerical simulation outcomes with field-measured data, an optimal construction scheme was deduced that effectively minimizes over-excavation: the peripheral hole spacing was adjusted to 1 m for grade Ⅲ surrounding rock and to 0.8 m for grade Ⅳ.
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Published: 28 June 2024
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