| 摘要 |
A method of replacing an existing buried pipe (1) with a replacement pipe comprising the steps of positioning a drilling unit (35) over the pipe to be replaced, operating the drilling unit to drive and guide a flexible drill st em (40) through the earth into an open end of the pipe to be replaced, further operating the drilling unit to extend the drill stem through the pipe to be replaced, attaching to the leading end of the drill stem a conical back reaming bit (45), attaching to the trailing end of the back reaming bit a flexible replacement pipe, and operating the drilling unit to apply a pullin g force and rotational torque to the drill stem, causing the back reaming bit to be driven and rotated laterally into and through the existing pipe to grind away the existing pipe and simultaneously pulling the replacement pipe into the pipe channel.
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