| 摘要 |
PURPOSE: A decompression structure for a double drain pipe is provided to restrain buoyancy by underground water by keeping the water level of underground water not to exceed the planned stable water level, and to prevent underground water from being drained off excessively by compulsion. CONSTITUTION: A decompression structure for a double drain pipe(20) comprises an outer pipe(21) having a through hole(21a) on one side of the outer circumference and an opening(21b) opened downward, and an inner pipe(24) composed of a horizontal pipe(22) provided with an inflow port(22a) to let underground water flow in and an end of the inflow port side exposed to the outside of the outer pipe via the through hole, and a vertical pipe(23) located in the outer pipe and extended upward from the horizontal pipe and provided with a discharge port(23a) to make influent underground water rise and overflow. |
