| 摘要 |
<p>PURPOSE: To attempt an exchange of the old tube for a new one without digging up the surface of the earth by exchanging a temporary tube for the new one after attaching a temporary tube to an excavator and advancing the excavator, putting it in the old tube and exchanging the old tube for the temporary one. CONSTITUTION: To the rear end of an excavator 4 having a drum larger in external diameter than an old tube 1, a temporary tube 5 having nearly the same diameter with that of a new tube 9 is attached. The method of exchanging for the temporary tube 5 is to advance the excavator 4 forward in an impactive manner with the leading end entering within the old tube 1, causing the old tube 1 to break, be pushed and spread toward the perimeter. Afterwards, to one end of the temporary tube 5, the new one 9 is connected, the temporary one 5 is pulled from the other end and the temporary one 5 is exchanged for the new one 9. As a result, the exchange can be performed without damaging the coating nor the lining of the inner plane of the new tube. Furthermore, less thrust power means reduction in affecting the surrounding ground unfavorably.</p> |
