| 摘要 |
Method and apparatus for drilling overburden covered rock which may or may not be submerged. The apparatus comprising a first drilling machine having a rotary drill head with a hollow drive spindle to which is connected a sectional cylindrical outer casing having a ring bit at its free end. The hollow drive spindle being located between a pair of vertically disposed parallel guide members for axial movement therebetween. A second drilling machine independently operable and having a drill string mounted to the drilling machine above the hollow drive spindle and co-axial therewith so that the drill string can be put down through the hollow drive spindle and outer casing to drill bed rock.
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