| 摘要 |
PURPOSE:To prevent the clogging of a filtering material by a method in which a soil agglomerator is put between two paper or cloth sheets and many holes through which water can pass are provided in the sheets. CONSTITUTION:A soil agglomerator 5 and a net material 4 are put between two paper or cloth sheets 3 to forma filtering material. The filtering material is punched to form many holes 2 through which water can pass in order to obtain a filtering material 1 for underdrainage. When a culvert is formed by the material 1, the soil agglomerator 5 is dissolved in water coming from the upper part to form a water-resistant film on the surfaces of soil blocks below the material 1. Since fine soil agglomerates can be formed,the clogging of the material 1 can be prevented, and the draining function of the culvert can be kept excellently.
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