JPS62133241A - Method for preventing corrosion of pc cable anchor part - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for preventing corrosion of the anchoring portion of a PC cable used for anchors such as rock anchors and earth anchors.

[Prior art] Recently, P has been used for rock anchors and earth anchors.
For C cables, unbonded PC steel strands are increasingly being used because they can completely protect the free length from corrosion.

The anchor point Ha and fixing portion of this unbonded P Cil stranded wire are used in a bare state, with the covering sheath and lubricant and rust preventive agent such as grease removed. The tip of the anchor is protected by mortar, textured plastic, or 14 sheath and mortar. On the other hand, the PC cable is fixed to the fixing part by a wedge (wedge-shaped fixing device), and complex stress is applied to the fixing part.Furthermore, since it is a part where different metals come into contact, it is a part that is extremely susceptible to corrosion. . Therefore, in order to protect the bare PC cable part of the fixing unit that protrudes outside from the fixing device from corrosion due to the external environment such as rainwater, cover the entire PC cable with a cap, etc., and fill the cap with grease, etc. ing.

[Problems that the invention seeks to solve] Since the PC cable is fixed to the wedge in the state in which the VH sheath is peeled off, the PC cable near the wedge, which is inside the fixing device, is also outside the fixing device. Similarly, the wire is exposed from the bare PC steel. Even in such an inner portion, water may flow into the poling hole, creating an environment where corrosion is likely to occur.

Furthermore, even when grout is filled into the poling holes around the covering sheath, gaps may be created due to incomplete filling, and it is necessary to completely block the intrusion of corrosive substances into the PC cable anchorage. I couldn't.

Furthermore, such problems have occurred in cases other than those in which unbonded PC steel strands are used as cables. In other words, in order to separate the entire free length of the bare PC steel strand from the primary ground, it is placed in a protective tube made of vinyl chloride or the like, and even when the inside of the protective tube is filled with an anticorrosion filler, the vicinity of the fixing device must be A similar problem occurred because the PCw4 strands were bare.

Therefore, an object of the present invention is to provide a corrosion prevention method that can protect the PC cable fixing portion inside the fixing device from corrosion by simple construction.

[Means for Solving the Problems] In the present invention, the outer periphery of the PC cable near the PC cable fixing section is covered with a steel pipe in order to prevent corrosive substances from entering the PC cable fixing section.

[Function] In this invention, since the outer periphery of the PC cable near the PC cable fixing part is covered with a steel pipe, it is possible to effectively block the intrusion of rotten substances into the PC cable fixing part by the steel pipe. can.

[Embodiment] FIG. 1 is a sectional view showing a first embodiment of the present invention. In FIG. 1, two unbonded PC steel strands 1 are inserted into a poling hole 12 formed in the ground 11. The unbonded PC steel stranded wire 1 is constructed by covering a PCM stranded wire 2 with a sheath 3 via a grease 4. The anchoring portion of the unbonded PC steel strand 1 is inserted into the insertion hole 6 of the bearing plate 5.

In the insertion hole 6, the unbonded PCI stranded wire 1 has the sheath 3a3 and grease 4 removed, and the PCI stranded wire 2
It is only in a naked state. The three PC8g stranded wires 2 are further inserted into the wedge 8 and fixed and fixed within the wedge 8. The wedge 8 is attached to a sleeve 7, and the sleeve 7 is attached around the insertion hole 6 of the pressure bearing plate 5. sleeve 7
A steel pipe 9 is installed around the insertion hole 6 of the bearing pressure plate 5 on the side opposite to the side where the fixing device such as the wedge 8 is provided.
The unbonded P CtlQ is provided to cover the stranded wire 1 .

The steel pipe 9 has an unbonded P disposed therein.
The C steel is appropriately selected and installed so as to minimize the gap between it and the FAl. The steel pipe 9 is attached to the bearing pressure plate 5 by a method such as welding,
It is attached closely to the bearing plate 5 so as to block the intrusion of corrosive substances from the outside. Ground 11 and bearing plate 5
A concrete 10 is provided between the two, and the steel pipe 9 is provided so as to pass through the concrete 10.

Here, in order to explain the function and effect of this embodiment,
An example of a conventional PC cable fixing part structure is shown in a cross-sectional view in Figure 5. In Figure 5, the structure is similar to that in Figure 1 except that the outer periphery of the unbonded PC steel strand is not covered with a steel pipe. It is configured in the same way. Inside the insertion hole 6 of the bearing pressure plate 5, the PC 14 strands 2 are exposed and are easily attacked by corrosive substances. Concrete 10 is provided between the poling hole 12 and the insertion hole 6 of the bearing pressure plate 5, and the concrete often has voids. Therefore, the polling hole 12
Corrosive substances such as water that have leaked into the concrete 10
The layer can be handled into the insertion hole 6 of the bearing plate 5. The corrosive substances thus reached corrode the bare PC steel strand 2 within the insertion hole 6.

Returning to FIG. 1, the operation and effects of this embodiment will be explained. In FIG. 1, a steel pipe 9 is provided that covers the unbonded C steel strand 1 with almost no gaps, and the steel pipe 9 is attached closely to the bearing plate 5. Therefore, corrosive substances in the polling hole 12 do not enter the insertion hole 6 of the pressure bearing plate 5 because it is blocked by the steel pipe 9.

FIG. 2 is a sectional view showing a second embodiment of the invention. If there is a slight gap between the unbonded PC steel strand 1 and the steel pipe 9, and there is a risk that corrosive substances may enter through this gap, as shown in Fig. 2, the steel pipe 9
The steel pipe 9 and unbond PC steel stranded wire 1 at the end of
An anticorrosion tape 13 may be wrapped around the boundary between the two. By wrapping the anticorrosive tape 13, it is possible to more completely prevent the intrusion of corrosive substances.

Also, as an alternative method for wrapping anti-corrosion tape, use Unpond PC! A method of filling a filler such as resin into the gap formed between the outer circumference of the I-stranded wire and the inner circumference of the steel pipe is also recommended.

FIG. 6 is a sectional view showing another example of the conventional PC cable fixing section structure. As shown in FIG. 6, when a plurality of unbonded PC steel strands 1 are fixed to one fixing device 17 (anchor head), the unbonded PC wires 1 are usually attached to the bearing plate 5.
A large insertion hole 6 into which all the plurality of C steel stranded wires 1 can be inserted is provided so that bearing pressure is applied to the bearing pressure plate 5 on the outer peripheral surface of the fixing device 17. When applying the method according to the present invention in such a case, the steel pipe is fixed to the fixing tool 17.
Although it is possible to directly attach the fixing device 17 to the lower surface of the fixing device 17, there is a risk that the material of the fixing device 17 may be changed due to welding when attaching the m-tube pipe. Therefore, as shown in FIG. 3, it is preferable to interpose a thin steel plate 14 between the bearing pressure plate 5 and the fixing device 17, and to attach the steel pipe 9 to the steel plate 14. Even in the case of the embodiment shown in FIG. 3, since the bare PC steel stranded wire 2 is sealed by the steel pipe 9, there is no risk of corrosion due to the intrusion of corrosive substances.

Furthermore, the method of the present invention can be applied to cases other than the case where unbonded PC steel strands are used as a cable. For example, it can also be applied to bare PC 114 stranded wire enclosed in a protective tube to separate the entire free length from the primary grout 1-. Examples of such applications are shown in the fourth section.
It is shown in cross section in the figure. In FIG. 4, the polling hole 12
Two PC steel stranded wires 2 are inserted into the PC.
The m-stranded wire 2 is surrounded by a protective tube 15 made of vinyl chloride or the like. The inside of the storage tube 15 is filled with an anticorrosion filler 16. A steel pipe is provided so as to cover the protective tube 15, and is attached to the support plate 5 by welding or the like. Steel pipe 9 and protection pipe 1
An anti-α tape 13 is wrapped around the boundary portion with 5. However, if there is almost no possibility that a gap will be formed between the pipe 15 and the steel pipe 9, such anti-corrosion tape 13 may not be wrapped.

The PC steel stranded wire 2 in the insertion hole 6 of the bearing pressure plate 5 is in a bare state without the anticorrosive filler 16 around it.

Therefore, it is in a state where it is easily corroded by corrosive substances, but since the steel pipe 9 and the anticorrosion tape 13 block the intrusion of corrosive substances, there is no risk of corrosion. In some cases, instead of wrapping the B gold tape, the gap between the protective tube 15 and the steel pipe 9 may be filled with resin or the like.

[Effects of the Invention] In this invention, since the outer periphery of the PC cable near the PC cable fixing part is covered with a steel pipe, the steel pipe effectively blocks the entry of corrosive substances into the PC cable fixing part. be able to. Therefore, by using the method of the present invention, it is possible to protect the PC cable from corrosion from corrosive substances such as water flowing out of the polling hole.

Further, since the method of the present invention can be carried out in a simple construction of 1 m, it is widely used in conventional PC cable necking sections.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a first embodiment of the invention. FIG. 2 is a sectional view showing a second embodiment of the invention. FIG. 3 is a sectional view showing a third embodiment of the invention. FIG. 4 is a sectional view showing a fourth embodiment of the invention. FIG. 5 is a sectional view showing an example of the structure of a conventional PC cable fixing section. FIG. 6 is a sectional view showing another example of the conventional PC cable fixing section structure. In the figure, 1 is an unbonded PC steel stranded wire, 2 is a PC steel stranded wire, 3 is a sheath, 4 is a grease, 5 is a bearing plate, 6 is an insertion hole, 7 is a sleeve, 8 is a wedge, 9 is a steel pipe, 12 13 indicates a polling hole, and 13 does not indicate an anticorrosive groove.

Claims (4)

[Claims] (1) A method for preventing corrosion of a PC cable anchorage, which comprises covering the outer periphery of the PC cable near the PC cable anchorage with a steel pipe in order to prevent corrosive substances from entering the PC cable anchorage. (2) The steel pipe and the P at the end of the steel pipe
2. A method for preventing corrosion of a PC cable fixing part according to claim 1, characterized in that an anticorrosive tape is wrapped around the boundary with the C cable. (3) PC cable fixing according to claim 1, characterized in that a filler is filled in a gap formed between an outer circumference of the PC cable and an inner circumference of the steel pipe. Corrosion prevention method. (4) The method for preventing corrosion of a PC cable fixing section according to claim 3, characterized in that a resin is used as the filler.