| 摘要 |
PROBLEM TO BE SOLVED: To achieve drainage of underground water, at a low cost, from an upper water-bearing layer while stopping the drainage thereof from a lower water-bearing layer, in draining underground water from the water-bearing layers above and below a low-permeable layer by installing one deep well.SOLUTION: An underground water drainage device 10, which drains underground water from a free water layer 2 and an artesian aquifer 4 respectively located above and below a low-permeable layer 3, comprises: a casing 12 which has water passing sections 12A and 12B respectively positioned at depths of the free water layer 2 and the artesian aquifer 4; a submerged pump 14 which is installed in the casing 12 and can move up and down; a lid member 24 fitted to a lower portion of the submerged pump 14; and a flange 22 which is arranged between the upper and lower water passing sections 12A and 12B inside the casing 12 and has a circular hole 22A being opened and closed by the lid member 24 moving up and down together with the submerged pump 14. |
