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For large cross-section tunnel blasting, the rock mass in the middle of the tunnel face often experiences the phenomenon of “bulging” due to the unreasonable arrangement of the cutting holes. In order to eliminate the “bulge belly” phenomenon in large cross-section tunnel blasting, a new method of “wedge cut+high-energy hole” blast hole layout was proposed. Taking the Gonghe Village Tunnel of the Luqiao Expressway in Yunnan Province as the engineering background, a numerical model of “wedge-shaped cut+high-energy hole” was established using finite element software LS-DYNA. The effective stress at the bottom of the blast hole and dynamic damage of the rock mass were studied and compared with the on-site tunnel cut blasting plan. At the same time, the proposed new method was verified through on-site blasting experiments. The research results indicate that the “wedge cut+high-energy hole” blasting hole layout method can effectively eliminate the “bulge” phenomenon, reduce the number of cut holes and digital electronic detonators, and determine the rationality and applicability of this method. Besides, the stress values generated by measuring points 1, 2, and 3 at the bottom of the main cutting hole are relatively small. As the stress sharply rises to 454.9 MPa, the middle-retained rock mass can be effectively broken after the main cutting hole blasted with the high-energy hole explodes. Using the improved blasting method, the excavation efficiency increased by 16.9%, the average utilization rate of blast holes reached 91.5%, and the explosive consumption reduced by 19.7%. The proposed layout method of “wedge-shaped cutting+high-energy holes” for large cross-section tunnels can not only ensure construction safety, but also achieve the effect of reducing costs and improving construction efficiency.
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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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