| 摘要 |
PURPOSE:To decrease a term of works, by a method wherein a branch pipe member is disposed opposite to a main pipe member, and the water gradient of each branch pipe member is set to a value about equal to that of the branch pipe member located on the upper stream end side of the main pipe member. CONSTITUTION:During a rainfall, each branch pipe member 3 collects rainwater penetrating through surface soil 15 and a filter part 16 formed by a filter member such as crushed stones. The collected rainwater flows through the branch pipe member 3 and is discharged from a drainage end 11. The drained water penetrates through a filter member 17 in an excavated groove 6, and flows through a main pipe member 2 and discharged through a drainage end into a water collection inlet 8. This, since the water gradient of each branch pipe member 3 is about equal to the water gradient, i.e., a minimum water gradient, of a branch pipe member 3a, positioned on the upperstream end side of the main pipe member 2, causes uniform and rapid drainage of rainwater throughout the whole of a ground G. |
