| 摘要 |
<p>PROBLEM TO BE SOLVED: To smoothly perform cable inserting work without damaging the cable by avoiding the occurrence of steps or stepped part at the opening of an inserting hole in a block manufacturing process. SOLUTION: In a manufacturing method for blocks for an underground common cable ducts using a bar-shaped inner formwork 12 to be inserted from a side wall 14 of an outer formwork 11 to the inside of the outer formwork, a section of an inner formwork near the inner surface of the side wall of the outer formwork, in a state where the inner formwork is inserted to the inside of the outer formwork, is gradually enlarged at an enlarging portion 16, and by this enlarging portion 16, an enlarged portion of an opening 18 of an cable inserting hole 13 of a block 9 can be formed. A smooth curved shape is created for the shape of the enlarged portion in the section containing the axis of the underground cable duct.</p> |
