小井眼的第二种形式包括使用了在采矿工业中使用的硬岩石中的勘探技术。

A second form involves technology used for exploration boreholes in the hard rock mining industry.

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旋转冲击钻井技术依靠冲击器产生冲击载荷并作用在钻头上来破碎岩石。该技术能够有效提高硬地层钻井速度，能够防止硬地层及复杂地层钻井中的井斜问题。

The rotary percussion drilling technology have the advantage to raise the hard rock well drilling speed effectively, prevent the borehole deviation in the hard rock or the complicated geologic strata.

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因此，将岩石可切割性划分为软、中软及中硬三个级别，对掘进过程中岩石的可切割性进行识别。

So the rock cuttabilities are divided into three levels as soft, medium soft and medium hard, based on which the rock cuttabilities along the tunnel is recognized.

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因此，将岩石可切割性划分为软、中软及中硬三个级别，对掘进过程中岩石的可切割性进行识别。

So the rock cuttabilities are divided into three levels as soft, medium soft and medium hard, based on which the rock cuttabilities along the tunnel is recognized.

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