| 摘要 |
PROBLEM TO BE SOLVED: To provide a manhole float-up prevention device which is easy to install, and can shorten time of drilling work and reduce costs.SOLUTION: A manhole float-up prevention device 1 comprises an anchor member 11 installed in an unliquefied layer 2a from a bottom part in a manhole 3, a joining metal fitting 41 provided in a receiving frame 25 of a cover body 21, and a tension material 7 for connecting the anchor member 11 and the joining metal fitting 41. In installation of the anchor member 11, it is drilled from an invert board 37 in the manhole 3, and is inserted into drilled holes 51, 52 and 53, and is fixed to the unliquefied layer 2a by a grout material 19. The tension material 7 is connected at one end to the joining metal fitting 41 of the receiving frame 25 of the coover body 21, and is connected at the other end to the anchor member 11 via a connection member 14. Thus, when the manhole 3 tries to float up by liquefaction, float-up of the manhole 3 can be prevented by resistance force of the anchor member 11 fixed to the unliquefied layer 2a. |
