JPH0545630Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The invention relates to the structure of a PC cable for anchoring.
Especially when fixing PC cables to bedrock etc.
The present invention relates to the structure of a PC cable for anchors that has good adhesion to anchor grout by providing a grip on the PC cable.

[Conventional technology]

Fix the tip of the PC cable to a rock etc.
Anchor construction methods have been conventionally used in the construction of various structures in which an extending portion is fixed to a structure or the like and a prestress is applied to a PC cable located between the anchoring portion and the structure.

To fix this PC cable to the bedrock etc., first,
This is done by drilling a hole in rock or the like to a predetermined depth, inserting the tip of the PC cable into the hole, and then injecting anchor grout and solidifying it.

However, since PC cables are made of thin filaments and are made of steel, their adhesion with anchor grout is weak, so it is necessary to bury them at an extremely long depth, which increases construction costs and shortens the construction period. It was causing delays.

Therefore, the PC to be fixed with anchor grout
Japanese Patent Publication No. 1-38960 discloses a technique for increasing adhesion by winding and crimping a plurality of grips around the tip of a cable.

According to this technology, the distribution of adhesion stress near the tip of the PC cable changes as the tensile load increases.
The load at the end of the PC cable is the greatest (second
In the figure, paying attention to B-1 and B-2), the length of each of the above-mentioned grips is formed such that the grip inside the fixing part of the PC cable tip becomes sequentially longer.

[The problem that the idea aims to solve]

By the way, according to the above-mentioned technology, grips with approximately the same outer diameter but different lengths are sequentially wound and crimped around the PC cable, so when the number of grips to be crimped increases, the length of the PC cable increases. In this direction, the area occupied by the grip increases, and the exposed area of the PC cable decreases.

Therefore, if the number of grips to be crimped is increased,
This will approach the same situation as when the thickness of the PC cable is increased, limiting the number and length of the grips and effectively improving the adhesion stress between the PC cable and the anchor grout. There was a problem in that it was difficult to equalize this adhesion stress in the length direction of the PC cable.

Further, there is a problem in that a plurality of crimping devices having different lengths must be prepared depending on the length of each grip.

In view of the above points, the purpose of this invention is to dramatically improve the adhesion stress between the PC cable and the anchor grout, and to reduce this adhesion stress.
PC cables can be made uniform in the length direction,
For anchors that are easy to install and have excellent economic efficiency.
It is to provide the structure of PC cable.

[Means to solve the problem]

According to the present invention, the above purpose is to provide a structure of an anchor PC cable in which a plurality of grips are crimped near the tip of the cable to be fixed to a bedrock or a structure, etc., in which each of the plurality of grips has approximately the same length but different lengths. This is achieved by crimping the grips near the tip of the PC cable so that the outer diameter of each grip gradually increases toward the tip of the cable.

[Effect]

According to the above configuration, each grip formed with approximately the same length and different outer diameter is crimped near the tip of the PC cable so that the outer diameter of the grip gradually increases toward the tip of the cable. The larger the grip that is crimped on the side, the more resistance there will be to the force trying to pull out the PC cable.
The adhesion stress between the cable and the anchor grout can be dramatically improved, and the tensile stress of the PC cable can be absorbed by the grip, reducing the adhesion stress on the tip side, and this adhesion stress can be transferred to the length of the PC cable. It can be made uniform in the direction.

In addition, when crimping the grip to the PC cable, it is possible to prepare several kinds of crimping jigs that can adjust the outside diameter between the grip and the crimping device and insert them as appropriate. There is no need to prepare multiple crimping devices, and it is possible to easily attach multiple grips to predetermined positions using a single crimping device.
Workability is improved.

Furthermore, by increasing the outer diameter of the grip,
By creating a large resistance against the force that tries to pull out the PC cable, the adhesion stress between the PC cable and the anchor grout can be further improved, and the number of grips can be reduced accordingly. Manufacturing costs and construction man-hours are reduced, resulting in excellent economic efficiency.

〔Example〕

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

Figure 1 shows the vicinity of the tip of the PC cable according to the present invention, which is embedded and fixed in rock.

This PC cable 1 is inserted with its tip end over a predetermined length into an excavated hole 2, fixed in an anchor grout 3, and then fixed by applying prestress to the PC cable 1.

A plurality of grips 4 are wound and crimped around the outer periphery of the tip of the PC cable 1. The axial lengths L of these grips 4 are all formed to be substantially the same length. Each of these grips 4 has a disk or cylindrical shape, and is formed to have a different outer diameter D.

The grips 4, 4, . . . are crimped near the tip of the PC cable 1 so that the outer diameter D gradually increases toward the tip of the cable. That is, in the case shown, a total of five grips 4 are fixed to the PC cable 1, and the outer diameter D of the adjacent grips on the tip side of the cable is formed to be large, and the outer diameters of each grip are a, b,...e
As you move towards the tip of PC cable 1,
It is set to gradually increase so that a<b<c<d<e.

Here, by crimping the grip 4 to the PC cable 1, the grip 4 moves in the tensile direction.
In other words, it acts as a resistance to the force that tries to pull out the PC cable 1, and the outer diameter D of this grip 4
The larger the value, the greater the adhesion stress between the PC cable 1 and the anchor grout 3.

In addition, when the PC cable 1 is prestressed and the tip of the PC cable is fixed to a bedrock etc. with the anchor grout 3, the PC cable 1 is prestressed as shown by the broken line A in FIG. Since the tensile stress applied to the anchor grout 3 decreases toward the tip thereof, the adhesion stress of the anchor grout 3 naturally increases on the tension side.
Therefore, if the PC cable 1 without the grip 4 is simply fixed to the anchor grout 3, when the prestress tensile load increases, stress will be concentrated on the anchor grout 3 on the tension side of the PC cable 1. It is known that it occurs after a while and then destroys it.

Therefore, PC cable 1 and anchor grout 3
In order to equalize the adhesion stress with the PC cable 1 in the length direction of the PC cable 1, in this invention, the PC cable 1
By attaching the grip 4 at a predetermined position, the tensile stress of the PC cable 1 can be absorbed by the grip 4, and the adhesion stress on the tension side can be reduced and averaged as shown by the solid line B-3. That is, by forming the grips 4 with approximately the same length and different outer diameters, and crimping these grips so that the outer diameters of the grips gradually increase toward the distal end of the cable, the PC This makes it possible to equalize the adhesion stress between the cable 1 and the anchor grout 3.

The structure of the PC cable according to the present invention is constructed as described above, and when attaching the grip 4 to the PC cable 1, it can be pressurized using the crimping device 10 shown in FIG. 3, for example. .

That is, the crimping sleeve 4 inserted into the PC cable 1 is aligned at a predetermined position, and is crimped and fixed by applying pressure from above and below with split dies 11, 11.

In the work of crimping the grip 4 to the PC cable 1, a crimping jig 1 is used to adjust the difference in the outer diameter D between the grip 1 and the crimping device 10.
By preparing several types of crimping devices 2 and interposing them as appropriate, there is no need to prepare multiple crimping devices 10 of different sizes, and each grip 4 can be attached to a plurality of grips 4 using one normal crimping device 10. It can be easily attached to a predetermined location, making construction easier.

Furthermore, by increasing the outer diameter D of the grip 4,
By creating a large resistance to the force that tries to pull out the PC cable 1, the adhesion stress between the PC cable 1 and the anchor grout 3 can be further improved, so the number of grips 4 is reduced accordingly. This reduces manufacturing costs and construction man-hours, resulting in excellent economic efficiency.

Although the present invention has been described based on the embodiment shown in FIG. 1, it goes without saying that the number of crimped grips 4 and the mounting position of each grip 4 can be arbitrarily set as necessary.

[Effect of idea]

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 can be dramatically improved, and this adhesion stress can be made uniform in the length direction of the PC cable. It has practical effects such as easy construction and excellent economic efficiency.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing a lock anchor part using the structure of the anchor PC cable according to the present invention;
FIG. 2 is a graph showing the degree of adhesion stress of the present invention and the prior art for PC cables, and FIG. 3 is an explanatory diagram of caulking of the crimp grip using the press method. 1... PC cable, 2... hole drilling, 3... anchor grout, 4... grip, 10... riveting device, 11... splitting die.

Claims (1)

[Scope of utility model registration request] In the structure of an anchor PC cable in which a plurality of grips are crimped near the tip of the cable to be fixed to a bedrock or structure, each of the plurality of grips is formed to have approximately the same length and a different outer diameter,
A structure of a PC cable for an anchor, characterized in that each grip is crimped near the tip of the PC cable so that its outer diameter gradually increases toward the tip of the cable.