JPH078581Y2 - Structure of PC cable for anchor - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to an anchor PC cable, and in particular, when the PC cable is fixedly fixed to a rock or the like, a grip is provided so that the adhesion with the anchor grout is good. The above is related to the structure of the PC cable.

[Conventional technology]

The anchor method that fixes the tip of the PC cable to the rock bed etc. and the extension part to the structure etc. and prestresses the PC cable located between these anchoring part and the structure is the conventional method. Have been used in the construction of various structures.

To fix this PC cable to rock etc., first drill a hole in the rock etc. to a predetermined depth, then insert the tip of the PC cable into this hole and inject anchor grout to solidify it. I am doing it.

However, since the PC cable is made of thin wire and is made of steel, its adhesion with the anchor grout is weak, so it is necessary to make the embedding depth extremely long, which increases costs and delays the construction period. Was invited.

For this reason, a technique for increasing the adhesive force by winding and crimping a plurality of grips around the tip of the PC cable fixed to the anchor grout is disclosed in Japanese Patent Publication No. 1-38960.
It is disclosed by the publication.

According to this technology, the distribution of the adhesion stress level near the tip of the PC cable, the load at the tip of the PC cable becomes the largest as the tensile load increases, paying attention to the length of each grip The grip inside the fixed portion of the tip portion is formed so as to be gradually lengthened.

[Problems to be solved by the device]

By the way, as described above, in order to sequentially wind and crimp grips having different lengths around the PC cable, it is necessary to strictly maintain the dimensional accuracy, and a special caulking device must be prepared. At the same time, the sleeves for grip, for example, have to be individually prepared in different sizes. Along with that, it was necessary to manufacture various types of sleeves for grips of different sizes individually, and the work of crimping the grip onto the PC cable was also very complicated.

In view of the above points, the purpose of the present invention is to dramatically improve the adhesion stress between the PC cable and the anchor grout, and
An object of the present invention is to provide a structure of a PC cable which can make this adhesion stress uniform in the length direction of the PC cable, is easy to work on, and is economical.

[Means for Solving the Problems]

In order to achieve the above object, in the structure of the PC cable for an anchor of the present invention, the PC cable inserted along the drilled hole into which the anchor grout is injected and solidified, and the PC cable with a constant short length when viewed in the axial direction. A plurality of grips that are formed and are crimped and fixed substantially orthogonal to the axial direction of the PC cable so as to resist the tensile stress of the PC cable in the vicinity of the front end of the PC cable; The grips are formed to have the same length and the same outer diameter, and the pitches along the PC cable are arranged in rows so as to become gradually smaller toward the tip end side of the PC cable, and the axial length of each grip is set to the minimum. It is configured by setting the length as short as the interval pitch.

[Action]

According to the above configuration, since the grip is obstructed against the force to pull out the PC cable by crimping the grip to the PC cable, the adhesion stress between the PC cable and the anchor grout is dramatically improved.

Also, the tensile stress of the PC cable can be reduced by crimping multiple grips that have the same length and the same outer diameter so that the distance between adjacent grips becomes narrower toward the tip side of the PC cable. It can be absorbed by the grip to reduce the adhesion stress on the tip side, and the adhesion stress can be made uniform in the length direction of the PC cable.

Also, in crimping the grip to the PC cable, it is not necessary to prepare a special caulking device with a complicated configuration,
It is possible to easily attach a plurality of grips to predetermined positions by using a normal caulking device and simply aligning the pitches of the crimping intervals, thereby improving the workability. Further, since these grips are set to have substantially the same length and the same outer diameter, the grips can be manufactured in a large amount at one time, which is excellent in economical efficiency.

〔Example〕

Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows the vicinity of the tip portion of the PC cable according to the present invention, which is embedded and fixed in a rock or the like.

This PC cable 1 has its tip over a specified length,
After being inserted into the excavated hole 2 and fixed in the anchor grout 3, the PC cable 1 is prestressed and fixed.

A plurality of grips 4 are wound and crimped on the outer periphery of the tip end of the PC cable 1. The axial lengths L of the grips 4 are all substantially the same. Then, in these grips 4, the pitch between adjacent grips 4 is sequentially set to be small so that the crimping interval between the grips 4, 4 ... becomes narrower toward the inside of the fixed portion of the PC cable 1. It is crimped by. That is, in the case shown in the figure, a total of eight grips 4 are connected to the PC cable 1.
The pitches a, b, ... G between adjacent grips are gradually reduced toward the tip of the PC cable 1, and a>b>c>d>e>f> g. Is set to. And preferably, each grip 4
As is apparent from FIG. 1, the axial length L of is set to a length substantially equal to the minimum pitch g or pitch f. Further, each grip 4 is crimped and fixed substantially orthogonal to its axial direction so as to resist the tensile stress of the PC cable 1.

Here, since the grip 4 is crimped to the PC cable 1, the grip 4 becomes an obstacle in the pulling direction, that is, against the force to pull out the PC cable 1, so that the adhesion between the PC cable and the anchor grout Stress is dramatically improved.

Also, with the PC cable 1 prestressed,
When fixing the PC cable tip to the rock etc. with the anchor grout 3, the tensile stress applied to the PC cable by prestress decreases as it goes to the tip side, as shown by the broken line A in FIG. Therefore, the adhesion stress of the anchor grout 3 naturally increases accordingly on the tension side. Therefore, if the PC cable that does not crimp the grip 4 is simply fixed to the anchor grout, when the prestressing tensile load increases, stress is intensively generated in the anchor grout on the tension side of the PC cable, and then, It is known to gradually destroy.

Therefore, in order to make the adhesion stress between the PC cable 1 and the anchor grout 3 uniform in the length direction of the PC cable 1, by attaching the grip 4 at a predetermined position of the PC cable 1 in the present invention, the PC cable is pulled. It is possible to absorb the stress by the grip 4 and reduce the adhesion stress on the tension side as shown by the solid line B. That is, said Japanese Patent Fair 1
As disclosed in JP-A-38960, the lengths of the grips are not formed so that the inside of the fixing portion is sequentially lengthened, and the grips 4 having the same length and the same outer diameter are used. By similarly crimping each grip 4 so that the pitch of the mounting position becomes smaller toward the inside of the fixed part, it is possible to equalize the adhesion stress between the PC cable 1 and the anchor grout 3 as in the above technique. It becomes.

The structure of the PC cable according to the present invention is configured as described above. When the grip 4 is attached to the PC cable 1, in addition to the extrusion method using a die described in JP-B-1-38960, for example, as shown in FIG. The crimping device 10 shown can be used for pressure pressing.

That is, the crimping sleeve 4 inserted through the PC cable 1 is aligned at a predetermined position, and the split dies 11 and 11 are pressed from above and below to crimp and fix the PC cable 1 while keeping a predetermined gap therebetween. The work may be performed by sequentially performing press working while narrowing the interval between the grips 4 toward the tip of the.

The grip 4 that can be used in the present invention is short, and therefore, if it is crimped and fixed by the device 10 described above, a sufficient fixing force with the PC cable can be obtained. Therefore, there is no need to prepare a special caulking device for crimping the grip 4 to the PC cable 1.

The present invention has been described based on the embodiment shown in FIG. 1, but the size of each grip 4, the number of crimps and the mounting position are as follows.
It goes without saying that it can be arbitrarily set if necessary. Further, the pitch of the crimping intervals of the grips is set so that a to g become gradually smaller toward the tip side of the PC cable, but not limited to this, for example, on the tension side of the PC cable with the largest load. A small number of grip groups are installed side by side, and a large number of grip groups are arranged on the tip side, etc.
It is not always necessary that the grips are sequentially arranged and the pitch intervals are set.

[Effect of device]

As described above, according to the structure of the PC cable of the present invention, the adhesion stress between the PC cable and the anchor grout is dramatically improved by crimping the grip to the PC cable, and the tensile stress of the PC cable is also improved. The grip absorbs the adhesive stress on the tip side to reduce this adhesive stress.
It can be made uniform in the length direction of the PC cable.

Further, since the grips to be crimped to the PC cable can be manufactured with the same size, it is not necessary to separately manufacture a plurality of sizes of sizes, and a large amount can be manufactured, so that the manufacturing cost can be reduced.

Furthermore, when each grip is crimped to the PC cable, it can be performed by an ordinary pressure press method, so that there are practical effects such as good workability.

[Brief description of drawings]

FIG. 1 is a sectional view showing a lock anchor portion using a PC cable for an anchor according to the present invention, FIG. 2 is a graph showing the adhesion stress level between the present invention and the prior art of a PC cable, and FIG. 3 is a press. It is explanatory drawing of the crimping process of the crimp grip by the method. 1 ... PC cable; 2 ... Drilling hole; 3 ... Anchor grout; 4 ... Grip; 10 ... Caulking device; 11 ... Split die.

Claims (1)

[Scope of utility model registration request] 1. A PC cable inserted along a hole into which an anchor grout is injected and solidified, and a PC cable formed in a short length when viewed in the axial direction of the PC cable, and the PC cable is provided near the tip of the PC cable. A plurality of grips crimped and fixed substantially orthogonal to the axial direction of the cable so as to resist tensile stress of the cable, and each grip is formed to have the same length and the same outer diameter, Lined up so that the spacing pitch along the PC cable becomes smaller toward the tip end side,
Moreover, the structure of the PC cable for anchors is characterized in that the axial length of each of the above-mentioned grips is set to a short length of about the minimum interval pitch.