JPH0138960B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of fixing a cable such as a PC strand to a bedrock or the like by providing a grip to greatly improve the adhesion between the PC strand and mortar.

One example of conventional fixing methods is to fix the end of a PC strand to a rock, etc.
The rock anchor method, in which concrete is poured after prestressing is introduced, is increasingly being used for the construction of underground power plants, etc. this
The ends of the PC strands were fixed by drilling a deep horizontal hole in the rock 1, injecting cement mortar 2, and inserting the tip of the PC strand 3 to solidify, as shown in Figure 1. .

However, this method mainly uses cement and PC
Due to the weak adhesion to the strands, a length of 4 m was required, causing delays in construction and increased costs.

By fixing the grip to a cable such as a PC strand, this invention dramatically increases the adhesion force with cement mortar and reduces the required drilling length by approximately 1/2.
I was able to make it 4.

FIG. 2 shows an embodiment of the invention, in which several crimping grips 4, 4', 4'' are crimped near the end of the PC strand 1, and cement mortar 2
It is inserted inside and solidified. In this case, as shown in Figure 1, the distribution of the adhesion stress S near the tip of the strand changes as →→ as the tensile load increases, and eventually the load at the tip of the PC strand is the largest, and this part It is necessary to completely fix the adhesion between the mortar and the mortar. For this reason, it is best to use the longest grip that guarantees the adhesion force between the PC strand and the crimp grip up to the breaking strength of the PC strand, and then use progressively shorter grips that are proportional to the adhesion force between the PC strand and the mortar.

When attaching such a crimp grip to a PC strand, the endmost grip can be easily attached using an extrusion method, but in order to attach it to the middle position of the PC strand, it is best to use a pressure press method. Probably common. That is, as shown in FIG. 3, the crimping sleeve 4 inserted into the PC strand is crimped and fixed by applying pressure from above and below with the split dies 5, 5. Although this method has the advantage that the grip 4 can be easily fixed to any position on the PC strand, it is dimensionally unstable and has aesthetic problems such as the occurrence of burrs 6.
The adhesion force between the PC strand and the PC strand is insufficient, and it is necessary to use a long crimping sleeve to hold the PC strand with sufficient strength.

FIG. 4 shows a crimping device suitable for carrying out the invention. When crimping the grip onto the PC strand by extrusion using a die,
As is well known, after inserting the end of the PC strand 3 into a die 8 fixed to one side of the frame 7 and covering it with a crimping sleeve 4, the frame 7 is
The push rod 10 of the ram 9 provided on the other side is pressed by the jack 11, and the crimping sleeve 4 is reduced in diameter by the die 8 and crimped and fixed to the PC strand. In the caulking device shown in FIG. 4, a hole 12 of a size that allows the PC strand 3 to be inserted freely passes through the center of the ram 9 and the push rod 10, and the hole 12 is used to freely insert the PC strand 3. The crimp grip can be caulked at the desired position. For example, the second
To make the grip shown in the figure, in order to caulk grip 4'' and then caulk 4', return the left end of PC strand 3 to the die entrance, and then use a crimp with a hole slightly larger than strand 3. After inserting the strand 3 through the sleeve 4' to the desired position (Fig. 4a), the ram 9 is operated again to press the crimp sleeve 4' toward the die 8, and the sleeve 4' has an outer diameter. As the diameter of the crimping grip is reduced, its inner diameter is also reduced and it is firmly crimped onto the outer periphery of the strand 3. (Fig. 4b) In this way, the crimping grip extruded by the die undergoes uniform plastic processing. Therefore, there is no instability in the length, and a stable and high deposition efficiency can be obtained with a short length, and there is no burr generation.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view showing the lock anchor part of the conventional method, Fig. 2 is a cross-sectional view showing the lock anchor part of the present invention, Fig. 3 is an explanatory diagram of the crimping process of the crimp grip by the press method, and Fig. 4 is a cross-sectional view showing the lock anchor part of the conventional method. It is an explanatory diagram of extrusion processing using a die, and the symbols in the diagram are as follows. 1: Rock wall, 2: Cement mortar, 3: PC strand, 4: Crimping grip, 5: Split die,
7: Frame, 8: Dice, 9: Ram, 10: Push rod, 11: Jacket.

Claims (1)

[Claims] 1 In a method in which multiple grips are crimped at arbitrary positions on a PC cable and the grip portion of the PC cable is fixed to a predetermined part of rock or a structure using cement mortar, etc., the length of each of the grips is fixed. The inside part is made to be longer,
A method for fixing a PC cable for an anchor, characterized in that the PC cable is crimped by extrusion processing.