| 摘要 |
PROBLEM TO BE SOLVED: To improve operation efficiency by constructing a succeeding tunnel parallelly with a preceding tunnel and disposing a water jet nozzle at a forward end of a skin plate, i.e., a part opposed to the outer wall surface of the preceding tunnel, so as to be oriented forward. SOLUTION: A lining body 21 of a succeeding tunnel 12 is constructed at the rear of a shield machine 13. Excavated earth and sand is discharged to the rear by means of an earth removal device 23. A water jet nozzle 24 is provided on each side of the device 23 so as to be oriented forward. If a compressing pump is actuated, jet water ejected from the nozzle 24 toward the lower front side of the machine 13 blows off earth and sand before the machine 13 and on the periphery of the outer upper surface of a preceding tunnel 11 as well to clean the outer upper surface of the tunnel 11. Thus stress due to excavation is not exerted on the tunnel 11 through the earth and sand, and damage to the tunnel 11 due to earth and sand can be avoided. |
