| 摘要 |
PROBLEM TO BE SOLVED: To provide a propulsion tube construction method to thrust forward a propulsion tube, where a wide installation space can be taken for a launcher, a launching pit can be installed after installing a pit, and there is no need to repair the launching, arrival pits and their anchor bolts after laying the propulsion tube. SOLUTION: A steel-made casing 20 having cutting blades 21 at its leading end is attached to the leading end of a concrete circular casing 10 pressed fit into ground by turning or swaying it, to excavate a starting shaft 1. After excavating the starting shaft 1 to a predetermined depth, a bottom concrete is placed at the bottom of the steel casing 20, and a launcher 55 is installed within the steel circular casing 10 to drive forward the propulsion tube 60. COPYRIGHT: (C)2006,JPO&NCIPI
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