hole bottom

Spacing charging at blast hole bottom is studied to reduce the seismic, which can make the ratio of vibration reduction to 10-15% and reduce the ratio of boulder and root as accessorial method.

还进一步进行了孔底空气间隔器的降震实验的研究，其降震率达10～15%，作为张沟采场辅助的降震措施，并且有效地降低了大块率和根底的产生。

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Study on Fluid Velocity at The Hole Bottom in Large Diameter Reverse Circulation Rotary Drilling

大直径反循环回转钻井底冲洗液流速的研究

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Popularization and Application of The New Explosion Technology in Which Bamboo is Laid at The Blast Hole Bottom as Spacer

孔底竹筒间隔装药爆破技术的推广运用

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So that the hole bottom is damaged which is caused by the faulty operation can be prevented.

这样，在切削功能件切削时，限位杆或者限位杆下端不转，可以防止因误操作而使限位杆损伤孔底。

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The accumulation of high velocity jet on the hole bottom

高速射流在孔底的堆积

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With high pressure air current passing the clearance between the double tube down to the hole bottom and carrying the rock cuttings through the internal pipe up to the earth surface.

它是由动力头回转双壁钻杆进行钻进，用高压气流沿管壁间隙通到孔底后，携带岩屑由钻杆中心孔返回地面。

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