| 摘要 |
PROBLEM TO BE SOLVED: To provide a water impervious material injection type water impervious work causing little uneven solidification, and a polyvinyl alcohol-system injection type water impervious material. SOLUTION: A plurality of layers of water impervious sheets 6a, 6b are laid with circumferential edges closely brought into contact with the ground face 1 where a load is set, a space d is secured between the adjacent water impervious sheets 6a, 6b against the load by using a porous spacer 7, and a polyvinyl alcohol-based impervious material aqueous solution 10 with adjustable gelation time t by pH is injected into the gap d. Preferably, the aqueous solution 10 has a pH value making the gelation time t equal to or longer than a solution charging time t<SB>0</SB>into the gap d, and the gap d is evacuated when the aqueous solution 10 is injected. One of examples of the water impervious material is an aqueous solution 10 in which a polyvinyl alcohol-based polymer of the degree of polymerization of 500 or more, a water soluble crosslinking agent having in its molecules two or more methylol groups, and a pH adjusting agent are dissolved. The degree of polymerization, polymer concentration and the mole ratio of the methylol groups to the vinyl alcohol unit in the polymer impart given water impervious properties to the water impervious gel. COPYRIGHT: (C)2005,JPO&NCIPI
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