| 摘要 |
PROBLEM TO BE SOLVED: To provide a boring device and its method enabling the drilling of a borehole in an underground in an economical and highly direction-stable manner. SOLUTION: The borehole is formed by the rotating drive and simultaneous sinking operation of at least three collocated boring strings 7a, 7b, 7c. The boring strings contains cutting devices 10a, 10b, 10c for underground cutting operation. The end of the central boring string 7c on its ground side is offset from the outside boring string. The boring strings are connected to one another with a yoke 20 and mounted to be rotatable in the yoke. The yoke 20 has an angle displacement part 22 angled to the offset direction, near the offset central boring string. COPYRIGHT: (C)2004,JPO
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