| 摘要 |
PROBLEM TO BE SOLVED: To make it possible to smooth convey also gravel mixed with sedimentary sand through the inside of a scour pipe when a siphon scour method for reducing energy and cost necessary for scour work is adopted, make it possible to surely execute the scour work capable of corresponding also to the sedimentary sand mixed with gravel and to enable the execution of the scour work efficiently to facilitate the movement of a suction section for the sedimentary sand covering a wide range of the bottom. SOLUTION: A method for scouring sedimentary sand in a dam reservoir 5 is so constituted that a suction pipe 3 of one end of a scour pipe 1 used as the bottom is opened to the bottom of a lake of the dam reservoir 5, a discharge pipe 4 of the other end is opened to a diversion channel 6 in the downstream and that water and sedimentary sand 17 in the dam reservoir 5 are sucked up with siphon operation and are discharged to the diversion channel 6. Then, a projected thread 9 is made inside of an interior wall of the scour pipe 1 in the shape of a spiral to generate an eddy current, air is distributed to the center in the pipe with centrifugal operation by the eddy current, and gravel in the sedimentary sand is distributed to the circumference section in the pipe.
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