| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for installing a check valve on a peripheral wall of a manhole for cutting off a flow of water to the outside of the manhole from the inside of the manhole and allowing the flow of the water into the manhole from the outside of the manhole when inter-soil clearance water pressure outside the manhole increases, for preventing the manhole from floating by a liquefaction phenomenon of the ground in an earthquake. SOLUTION: A hole is bored in the manhole peripheral wall by using a core drill. Hole boring is stopped once after reaching about 80 to 90 percent of the thickness of the peripheral wall, and a core formed of an annular groove is taken out by extracting a core bit. Then, a notch is formed again in a core taken-out hole up to reaching near an outer peripheral surface by the core bit. After notching, a rupture metal fitting 37 is installed on the tip by extracting the core bit, and the check valve 35 having a slipping-out preventive claw 15 on the outer periphery is installed in the core drill, and is pushed in the core taken-out hole 32, and a wall part 33 remaining at the bottom of the hole 32 is broken through by the rupture metal fitting 37, and is ruptured into a small piece. COPYRIGHT: (C)2007,JPO&INPIT
|
