Does a 76 mm O hole drilled over 45 m deep remain straight? This is the question asked by the Engineering department at Placer Dome's Dome Mine in Timmins, Ontario before they could lay out the initiation sequence in a long-hole production stope. Everyone realized that the holes would wander over such great depths, but it was important to know where they went.
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机译：在45 m深处钻出的76 mm O孔是否保持平直？这是位于安大略省Timmins的Placer Dome's Dome Mine的工程部门提出的问题，然后他们才能确定长孔采场中的起爆顺序。每个人都意识到这些洞会在如此深的深度上徘徊，但是了解它们的去向很重要。
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