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In order to ensure the construction quality of large section shaft horsehead gate and reduce the damage caused by blasting, an advance crack zone blasting technology is put forward. According to the section design and engineering geological conditions, the section of Matoumen excavation, the gates at-199.5 m and-258.2 m of a certain underground mine are divided into upper layer, middle layer, and lower layer excavation zones. The construction sequence is: upper layer→middle layer→lower layer. Firstly, the advanced fracturing holes should be constructed along the excavation contour lines of each layer. The hole depth is equal to the driving depth of the horsehead gate. They are charged with decks and detonated before the main blasting area, which can achieve mutual penetration between holes. The "shock absorption ditch" shall be formed along the excavation contour lines of the horsehead gate, which can reduce the effect of blasting seismic wave propagation. Besides, each construction area of the horsehead gate is equipped with hole by hole millisecond delay detonations with an interval of 5~20 ms, which can achieve the interference and offset of the vibrations from the subsequent blasting and reduce the blasting impact on the large cross-section horsehead gate. It has been validated that the half-wall hole rate of the excavation contour line is higher than 95%. It can not only meet the requirements of controlling the quality of roof forming for the excavation of large cross-section gate in broken rock mass, but also reduce the cost of support and shotcrete.
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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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