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To enhance excavation speed in small-section tunnels and address the limitations of oblique and burn cut blasting techniques, a new burn cut blasting method combining long and short straight holes is proposed based on rock blasting theory, stress wave rock breaking theory, and sacrificial blasting theory. This method improves the burn cut blasting approach with equal resistance lines, eliminating the need for empty holes. The blasting parameters and cavity formation process are discussed in detail. Through field tests and the use of different detonators and cutting layouts, the performance of various cutting methods was evaluated in terms of blasting advance, powder factor, and over-excavation and under-excavation. The results show that the proposed burn cut blasting method is not constrained by tunnel cross-sectional area, allowing for independent hole depth design and optimal delay intervals to achieve staged and layered blasting. This technique enhances the role of free surfaces in the cutting process, reducing the minimal resistance line in deep holes. The resulted cavity is a regular rectangular shape, increasing blast hole utilization from 78.5% to 89.3%. Field tests show that, in small-section tunnel blasting, this method increases the advance from 1.6~2.2 m to 2.2~2.5 m compared to traditional inclined-hole cut blasting. Over-excavation was further reduced by 20%~30% when the displacement of surrounding holes remained within 10cm. The proposed cutting method effectively controls costs, improves operational efficiency, and offers both technical and economic advantages with improved blasting outcomes.
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| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |
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