| 摘要 |
PROBLEM TO BE SOLVED: To provide a method of constructing an optionally flat large cross section tunnel having a waterproof structure in an unconsolidated aquifer, at a low cost. SOLUTION: A first preceding tunnel 2 is constructed in an excavated area of the large cross section tunnel 1 by a shield method, and a second preceding tunnel 3 juxtaposed with a predetermined distance from the first preceding tunnel 2 is constructed outside the excavated area of the large cross section tunnel 1 by the shield method. After boring a straight boring hole 5a radially from the peripheral wall 2a of the first preceding tunnel 2 toward the ground G, high pressure dehydration injection of a chemical solution into the ground G is carried out from the straight boring hole 5a to form a hardly water permeable area 5 surrounding the excavated area of the large cross section tunnel 1. From the second preceding tunnel 3, a circular boring hole 4a is bored to surround the hardly water permeable area 5, and then low pressure infiltration injection of the chemical solution into the ground G is performed from the circular boring hole 4a to form an impervious area 4. The excavated area of the large cross section tunnel 1 is then excavated. COPYRIGHT: (C)2006,JPO&NCIPI |
