The invention relates to a construction method for demounting a cable-stayed bridge fast. An anchor is hard to be removed under the condition that a stayed cable has
cable tension, a special tool is used for transforming the stress of an upper anchor ring, a cable and a lower anchor head into zero, then an upper anchor head is
cut by compulsion, the cable is chopped up, and the lower anchor head is removed for saving the anchor-removing time, so as to change cables fast. A
punching tensioning jack is installed at an anchor
pipe opening of the cable. A tension rod is arranged in the jack. The tension rod tensions after penetrating into a tool anchor ring. The tool anchor ring is screwed into the
tail end of an anchor head to replace an old anchor ring, and the old anchor ring is taken out by cool
cutting. The jack is moved to the
tail of the tension rod by the repeated tension and release of the tool anchor ring to ensure that the cable still has 30 to 40 tons of tension. Two sets of cable clamps are used for clamping two ends of the cable to be chopped up. A
windlass pulley set is connected between the cable clamps. The
pulley set is frapped to transform the internal force of the
cut section of the cable into zero and chops the cable. A hoisting apparatus is used for taking out the
cut cable on a
tower. A hollow
drill rod is used for drilling concrete or
epoxy mortar in a cable anchor
pipe at the end of a beam. The
punching tensioning jack is used for pulling out the anchor head by compulsion.