| 摘要 |
PURPOSE:To prevent the breakage of a covering sheet by a method in which the loosened portion of a covering sheet is set on the top end side of a slope, and both end portions of the loosened portion and the inside connected portion are orderly released toward the direction of the bottom under water by tensional forces in such a way as to expand it to the direction of the bottom under water. CONSTITUTION:A sheet 1 is lapped on the top end 16 of a dam 13 and fixed by anchors 17. Objects 18 to be charged are dumped onto the bottom 19 under water to tense the end 20 on the bottom 19 side of the sheet 1 by the gravity and pressure of the objects to be thrown 18, whereupon the tensional force is transmitted to the loosened portion 2 of the sheet 1, the connector 8 of the connected portion A is broken, and the folded portion 6 is expanded to the direction of the bottom 19 under water. When the objects 18 are further deposited, the connectors 10 and 11 of the connected portions B and C of the sheet 1 are broken in sequence and the sheet 1 is expanded to the direction of the bottom 19 under water.
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