| 摘要 |
PROBLEM TO BE SOLVED: To provide a permanent form for base concrete, which is not bulky and easy to transport, which does not require time and labor for installation at a work site, and which is not deformed with soil pressure due to back filling or inner pressure due to concrete placing.SOLUTION: Four permanent forms 20 each having a substantially L-shaped form in a plane view are combined together at respective ends in a quadrangle. A first abutting part 21 and a second abutting part 23 are provided respectively at both joints of the permanent form 20, the abutting parts 21, 23 of adjacent permanent forms abutting with each other. A projection 22 is provided projecting from the tip of the first abutting part 21 while a projection enclosing part 24 having a shape almost enclosing the projection 22 from outside is provided protruding from the tip of the second abutting part 23, and a little back filling is carried out before concrete placing to stabilize the permanent forms 20. |
