| 摘要 |
PURPOSE:To prevent the inner circumferential face of a main tube from being injured by means of mud feed and drain tubes going in and out in the main tube, when the main tube of a direct push propulsive double steel tube is propelled in the earth. CONSTITUTION:When a direct push propulsive double steel tube 5 is propelled with a prime pusher jack 8 and mud feed and drain tubes 10, 11 are taken in and out against the main tube 7 of the double steel tube 5, a holding member 13 consisting of a tube receiving base 13a and an elastic wheel 13b is fitted to the mud feed and drain tubes 10, 11. While running the holding member 13 in the main tube 7, the mud feed and drain tubes 10, 11 are taken in and out of the main tube 7. |
