| 摘要 |
PROBLEM TO BE SOLVED: To permanently prevent the permeation of ground water into a tunnel and the leakage of water to a surrounding ground through a defective part even when partial cracking or breaking occurs partially in coating concrete or a water-barrier sheet. SOLUTION: A drain material 14 is placed between a tunnel ground E and coating concrete 18, a compressor 26 is connected to the drain material 14, and the water pressure in the drain material 14 is maintained to be higher than that in the tunnel 10 by the air pressure of the compressor.
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