| 摘要 |
PURPOSE:To increase safety, by backfilling the inside of a tunnel with a filler material while moving back in the tunnel after the pilot tunnel is excavated and the ground is improved and then excavating a large cross section shield including the backfilled part by a sealing type shielding machine. CONSTITUTION:After a pilot tunnel 19 is excavated by a semi-shielding machine 21 from a start shaft 11 or an arrival shaft 13 to an opposite shaft, a reagent is injected in the upper part to form an improved ground area 41. Next, the shielding machine 21 is forced to move back and a proceeding pipe 23 is drawn out. And a low strength filter like clay is poured in the cavity to form a filled part 53 having a nearly same condition as the original ground 49. Next, a large section shielding machine 51 is applied to excavate the lower part of the improved ground area 41 from the shaft 11 to the shaft 13 in the condition that the filled part 53 is included in the excavating area. In this way, a pneumatic method and removing works of obstacles become unnecessary and it can prevent accidents like ejection, oxygen deficiency, etc., by use of a sealing type shield. |
