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open underhand stopes
expl.
无支护下向台阶采矿法
矿工站在开采矿体上向下钻孔,将爆碎矿石抛掷到下一个台阶运走的爆破采矿法。虽然大都采用普通的下向钻孔,但在台阶底部局部也可采用水平孔
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