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| 天井深孔爆破法掘进采用深孔钻机,在天井断面范围内，沿天井全高钻完全部平行炮孔,然后进行分段或一次爆破成井的天井掘进方法。该法虽是采用凿岩爆破掘进天井，但其特点是工人不需进人天井内作业，工作条件好且安全 | |||
| drop raising: 2 phrases in 1 subject |
| Explosives and Explosive Ordnance Disposal | 2 |
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