| 摘要 |
PURPOSE:To prevent the blocking of crushed stone drain pile by providing a filter layer in the boundary between the crushed stone drain piles and its adjacent sand layer. CONSTITUTION:A cylindrical guide 9 in which roller groups 10 and 11 supporting upper and lower two-stage filter sheets are supported by struts 12 on a base plate 13 is provided in a freely assembling and detachable manner on the periphery of a casing 4 attached with a filter sheet 6 by a fitting ring 7. The guide 9 is set surrounding the casing 4, the sheet 6 is supported by the roller groups 10 and 11, sand layer 2 is excavated by earth auger (not illustrated), etc., and the casing 4 is penetrated. Then, while packing crushed stones 3 into the cylinder formed by the sheet 6, the casing 4 is pulled up. |
