| 摘要 |
<p>PURPOSE:To replace new tubes for existing tubes without damaging the nearby tube by a method in which an auger rod with a spiral blade is thrust through an existing tube, and a rotary rod having a cutting edge on its tip is inserted into a new tube and advanced rotationally. CONSTITUTION:An auger rod 17 with a spiral blade is rotationally penetrated from a starting vertical pit 22 until its tip reaches an arrival vertical pit 23, and a given length of a rod 17c is connected to the basal end of the rod 17. A rotary rod 19 tipped with a cutting edge 18 to excavate the end portion of an existing tube is fitted on the periphery of the rod 17, and a new tube 3 is inserted through a center holder into the rod 19 and rotationally advanced from the pit 22 side while breaking the existing tube by the cutting edge 18. Tube connection is performed by one-set basis sequentially, advanced until reaching the pit 23, and the cutting edge 18 is drawn out and removed in the pit 23. The others are drawn out and removed in the pit 22.</p> |
