这样允许钻头围绕岩石的中心圆柱体钻进，并通过钻头进入取芯桶。
This allows the bit to drill around a central cylinder of rock, which is taken in through the bit and into the core barrel.
通过对某高桩码头横梁裂缝深度的超声检测、骑缝取芯验证，说明对于活荷载引起的结构性裂缝，由于卸载后裂缝重新闭合，超声法检测存在局限性。
The ultrasonic method is unfit for inspecting the depth of crack originated from live load, since the crack will close after the load is removed.
通过对在钢筋混疑土、花岗岩等建筑物上钻孔特点的分析，本文设计了一种新型的取芯式薄壁金钢石钻头。
A new type of thin-wall diamond core drill bit is developed through the analysis of drilling feature on the r.
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