| 摘要 |
PROBLEM TO BE SOLVED: To obtain a drainage block construction continuously discharging the rainwater on a road surface to a sewer or the like, and diverting the rainwater to filtration and percolation to the underground when the amount of drainage exceeds a predetermined level so that the amount of outflow can be restrained and the rainwater can be circulated like the case where the underground water from which contaminated water is removed is recharged. SOLUTION: Outflow swallowing ports are formed in an inner face of a water passage part at a height of an ordinary water level or the like at predetermined intervals in a manner of communicating with an outer bottom face or an outer bottom recess part by the intermediary of a filter element. A control hole reaching an upper open face is formed in the communicating part. By fitting a detachable filter element cartridge to the communicating part from the control hole, the overflown water is filtered. The precast concrete drainage blocks which are thus structured are continuously placed on a percolation trench replaced with single grain size crushed stones of high porosity to maintain drainage capacity at the ordinary water level and to allow the water of higher level to fall and flow to a hollow storage part formed under the drainage blocks. Thus the overflown water is filtered and percolated to restrain the amount of outflow, remove the contamination and allow the water to percolate. COPYRIGHT: (C)2008,JPO&INPIT
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