| 摘要 |
A rock anchor for multi-stage grouting is provided to make pressure grouting of third grouting executed while a bore hole is expanded, to make a PC steel strand freely contracted and stretched, and to prevent the front end of the PC steel strand from being rusted. In a rock anchor for multi-stage grouting, a straight pipe is divided into a PE(Poly Ethylene) pipe(2) and a pull-out fixation pipe(20) having plural fixation body-annular protrusions(23). PE steel strands(9) are built in the PE pipe and the pull-out fixation pipe. A screw part formed to one end of the PE pipe is inserted in a pressed plate(8) and a nut(6) is fastened to the outside of the pressed plate. One end of each PE steel strand is detained to the pressed plate. The other end of each PE steel strand connects a connection member detained by adaptors(36) at the front end of the pull-out fixation pipe. One-ends of the PE pipe and the pull-out fixation pipe are formed as a cylindrical pipe closing by front end surfaces and plural flow holes are bored in the front end surfaces. A connecting pressure pipe(10) is arranged between the PE pipe and the pull-out fixation pipe and the ends of the PE pipe and the pull-out fixation pipe are inserted in the ends of the connecting pressure pipe. A connection pipe(5) with a screw part is inserted in the pressed plate and an opened part is situated to the outside. One-ends of the PE pipe and the pull-out fixation pipe are detained to the front outer periphery and the front end surface of the connection pipe. An end-sealing device is combined with the front end of the pull-out fixation pipe in a hermetic state by a sealing O-ring(25) interposed. A first grout injection pipe, a second grout injection pipe, a third grout injection pipe are supported to the outside of the PE pipe. The inner front end of the first grout injection pipe is situated to the outer periphery of the connecting pressure pipe and each inner end of the second and third grout injection pipes is situated to the outside of the PE pipe and a lower pressing cap(35).
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