Full
Outline
Aiming at the problems of roof over-excavation, roof failure and high block rate in the deep mining process of an iron mine, taking the ore body between －360 m and －450 m level of the mine as the engineering background, the optimization of blasting parameters for fan-shaped medium-length holes was carried out. Based on the mechanism of ore rock blasting fragmentation and the theoretical formula of blasting parameters, the theoretical value range of each blasting parameter was derived. Combined with the physical and mechanical properties of ore rock and the performance parameters of on-site explosives, Ansys LS-DYNA numerical simulation software was used to construct a stope blasting model with different hole bottom spacings, explosive unit consumption and resistance line combinations, and the effective stress distribution characteristics of the mine roof were analyzed. The results show that when the hole bottom spacing is 1.4 m and the explosive unit consumption is 2.09 kg/m3, the maximum effective stress of the monitoring grid in the room area is closest to the maximum dynamic tensile strength of the rock, which can fully break the ore rock in the hole bottom area, and the maximum effective stress of the roof monitoring grid does not reach the dynamic tensile strength, and the roof is stable. When the minimum resistance line is 1.6 m, the average maximum effective stress of the monitoring grid near the free surface is 44.31 MPa, and the peak value of blasting vibration velocity in the roof area is 18.51 cm/s, which does not exceed the allowable standard of blasting vibration safety. Based on the optimized parameters (hole bottom spacing 1.4 m, explosive unit consumption 2.09 kg/m3, minimum resistance line 1.6 m), the field industrial test was carried out. The bulk rate is reduced from 6% before optimization to 3%. The roof is well formed, the surface is flat, and there is no obvious crack and collapse. The research results can provide reference for the optimization of fan-shaped medium-length hole blasting parameters in similar deep filling stopes.
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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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