To accurately and efficiently cut a hole, ranging from a surface of a prestressed concrete member to a sheath, by limiting the hole to a narrow range, and to prevent corrosion of a tendon by additionally filling an imperfectly grouted part in the sheath with grout.
A slot 12, wherein a major axis is provided in the axial direction of the sheath 5, is cut in such a manner as to range from the surface of the concrete member 1 to an outer peripheral surface of the sheath. This cutting is performed by using a high-pressure water jet which is emitted from a nozzle 22. The nozzle, wherein two discharge ports 23 are provided in an axially symmetrical manner, turns the discharge ports, ejects high-pressure water while reciprocating in the axial direction of the sheath 5, and efficiently cuts the limited range while discharging cut aggregate etc. from inside a cutting port. An inlet and an outlet for the grout are provided in the slot which is formed in this way, and air in the sheath is discharged from the outlet while the grout is injected from the inlet.
FUJIWARA YASUHISA
TAKAYAMA HARUMITSU
Hiroyuki Matsumura