JPH0611996B2 - Removal anchor method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention is used for earth retaining work, construction of retaining walls for ports, and the like.
Removable anchor method.

<Prior Art> Currently, as a removal anchor, there is a core-type removal anchor that easily removes the PC steel material after the PC steel material is positioned on the outer periphery of a rod-shaped body called a center core and the center core is extracted when the anchor is removed. .

The structure will be briefly described with reference to the partial cross-sectional view of the fixing long portion of the conventional core type removal anchor shown in FIG.

That is, a center core b having a plurality of groove grooves a is located in the center of the fixing body, and a surface of the center core b is covered with a core cover c.

In the center hole of the center core b, a PC steel material d for core removal is inserted and fixed with a resin.

In each groove a of the center core b, two Ps for fixing are provided.
The C steel material e is accommodated, and the outer periphery thereof is constrained by a binding tape or the like.

<Problems to be Solved by the Present Invention><B> When the fixing material i is injected into the anchor hole g, the fixing material i easily escapes to the cracks in the anchor hole g, and is not easily removed in the gap of the fixing PC steel material e. It is difficult for the fixing material i to enter, and a gap j is formed between the groove a and the PC steel material e.

Therefore, the presence of the void j is a major factor that hinders the improvement of the proof strength of the anchor, which is required by the adhesion area of the fixing material i and the PC steel material e.

<B> As a method of injecting the fixing material i into the void j, a method of pressurizing and injecting the fixing material i can be considered.

However, as the injection pressure of the fixing material i increases, the degree of penetration of the anchor holes g into cracks and geologically weak areas increases, so that it is still difficult to penetrate the fixing material i into the voids j.

Therefore, this method simply wastes the fixing material i and is not suitable for practical use.

<Purpose of the present invention> The present invention has been made to solve the above problems, and increases the adhesion area and adhesion strength of the PC steel material and the fixing material while suppressing the waste of the fixing material to increase the yield strength of the anchor. It is an object of the present invention to provide a removal anchor method that can be improved.

<Structure of the Present Invention> Hereinafter, one embodiment of the present invention will be described, but the basic structure thereof will be described by taking a core type removal anchor as an example.

<A> Center core (FIGS. 1 and 3) The center core 1 has a plurality of continuous grooves 2 on its peripheral surface, as in the conventional type.

The center core 1 is formed of a synthetic resin because it forms a hollow hole that is effective for cutting the edge of the PC steel material for fixing at the time of removal.

The surface of the center core 1 is coated with a grease-like lubricant and covered with the core cover 3.

A PC steel material 4 for core extraction is inserted into the center hole of the center core 1 and bonded with a resin.

The center core 1 is installed in the range of the fixing long part.

<B> PC Steel Material (FIGS. 1, 2, and 4) As the PC steel material 5 for fixing, a PC steel strand is used, and two wires are arranged in each groove 2 of the center core 1.

The group of fixing PC steel materials 5 is constrained by using a binding tape 6, a spacer 7 or the like.

The cleaning hose is positioned inside the group of PC steel materials 5 over the range of the free length so that the cleaning hose can be pulled out.

<C> Tube (FIGS. 1 and 2) The tubular tube 9 is installed over the range of the free length portion of the PC steel material 5 for fixing.

At the boundary with the fixing long portion, asphalt or the like is injected to form a boundary seal 10 in order to prevent the fixing material from entering.

<D> Injection hose (FIG. 2) Only one of the eight PC steel materials 5 is replaced with the injection hose 11.

The injection hose 11 is a hose for injecting the fixing material into the corrugated sheath 12, and the tip of the injection hose 11 is opened at the tip of the fixing long portion.

<E> Corrugated sheath (Fig. 1) The corrugated sheath 12 is a tubular body that covers the entire length of the anchor.

The end of the corrugated sheath 12 is sealed with a water blocking material 13, and then an end cap 14 is attached.

<Operation> Next, a method of constructing the removal anchor will be described.

[Anchor Fixing Procedure] (FIGS. 1, 2, and 4) <A> Insertion of Anchor Cable An anchor cable covering the corrugated sheath 12 is inserted into the anchor hole 15.

<B> Injection of fixing material An external fixing material 16 such as cement paste is provided between the anchor hole 15 and the corrugated sheath 12 over the range of the fixing length portion.
Inject.

Then, the fixing material is pressure-fed by the injection pump from the base end of the injection hose 11 and the internal fixing material 17 is fed into the corrugated sheath 12.
Is injected under pressure.

Then, as shown in FIG. 4, the pressing force of the internal fixing material 17 in the fixing length portion acts to spread to the hole wall side of the anchor 15, but is restrained by the corrugated sheath 12 so that the center core 1 is fixed. Focus on the center.

Therefore, the internal fixing material easily wraps around to the back side of each fixing PC steel material 5, and the adhesion area of the PC steel material 5 and the internal fixing material 17 increases compared with the conventional case.

Further, the adhesion area between each fixing PC steel material 5 and the internal fixing material 17 increases, and the adhesion strength also increases due to the pressing force of the internal fixing material 17.

Further, when a gap is formed between the center core 1 and the core cover 3, the core cover 3 is pushed toward the center of the center core 1, so that the gap can be eliminated and the two can be brought into close contact with each other.

The pressurizing force of the internal fixing material 17 acting on the PC steel material 5 may be artificially applied by the injection pressure from the injection hose 11 or may be applied by utilizing the gravity of the internal fixing material 17.

Here, the method of utilizing gravity refers to a method of applying a pressing force obtained only by gravity acting on the filled internal fixing material 17, rather than artificially applying pressure. Even by the gravity acting on the filled internal fixing material 17, a sufficient pressing force can be obtained to cause the internal fixing material 17 to wrap around the back side of the PC steel material 5.

The method of artificially applying pressure is suitable for the upward facing anchor, and the method of utilizing gravity is suitable for the downward facing anchor. Also,
If the structure in which the end of the corrugated sheath 12 is sealed with asphalt or the like is adopted, the pressurizing effect can be further improved.

<C> Washing the free length portion with water After cleaning the inside of the tube 9 using the cleaning hose, the inside of the tube 9 is filled with rust preventive oil.

Then pull out the cleaning hose.

<C> Tension and Fixation After a predetermined curing period, tension and fixation are made on the base end of the PC steel material 5 by using a tensioning jack.

The tensioning method and fixing method of the PC steel material 5 are the same as the conventional method.

[Removal Procedure of Anchor] <A> Pulling out the center core (Fig. 5) Remove the fixing tool for fixing the anchor cable to release the fixing of the PC steel material 5.

Next, a PC for extracting the core exposed outside the anchor hole 15
A pulling force is applied to the steel material 4 to pull out only the center core 1.

A hollow hole 18 having the same shape as the center core 1 is formed in the fixing long portion after the center core 1 is pulled out.

<B> Pulling out PC steel material (Fig. 6) Applying pulling force to the base end of each PC steel material 5 to fix the internal fixing material 17
The PC steel material group 5 is cut off from the edge and pulled out.

Since the center core 1 which is a supporting member of the PC steel group 5 has been lost, the extracting force acts in the converging direction to facilitate the internal fixing material 1.
You can cut off from 7.

<Other Embodiments> The corrugated sheath 12 may be provided only over the range of the fixing length portion.

Further, instead of the corrugated sheath 12, a sheath having the same diameter without unevenness may be used.

Furthermore, an injection hose 11 for injecting the internal fixing material 17
Is disposed between the fixing PC steel material 5 and the corrugated sheath 12, the PC steel material 5 can be prevented from being lost.

<Effects of the Present Invention> Since the present invention is as described above, the following effects can be obtained.

<a> In the core type removal anchor, the presence of the corrugated sheath restricts the direction of the pressing force of the fixing material filling the inside of the sheath in the axial direction of the anchor. It becomes easy for the fixing material to wrap around the back side of the.

Therefore, the adhesion area and the adhesion strength of the fixing material and the fixing PC steel material are increased, and the yield strength of the anchor is improved.

<B> In the case of the core type removal anchor, even if a gap is formed between the center core and the core cover that covers the center core, the pressure applied by the fixing material acts in the direction of eliminating the gap, so that the adhesion between the two Can be achieved.

<C> Since it is possible to prevent the fixing material filling the inside of the sheath from leaking and permeating toward the anchor hole wall side, it is possible to secure a good anchor grout and improve the economical efficiency of construction.

<D> The sheath has a rustproof function.

Therefore, it is possible to sufficiently cope with the recent tendency that the temporary installation period of the anchor is prolonged.

<E> It is easy to apply to a known removal type anchor construction method.

<F> It is possible to suppress cracking of the cured fixing material.

[Brief description of drawings]

1 is an explanatory view of an embodiment according to the present invention and is a vertical cross-sectional view of a core-type removal anchor. FIG. 2 is a cross-sectional view taken along the line II-II of FIG. 1. FIG. 3 is a perspective view of an anchor cable. Figure: Partly enlarged view of the fixing length part during fixing Fig. 5 and 6: Explanatory drawing when removing the anchor Fig. 7: Partly enlarged view of the fixing length part of the conventional removal anchor

Claims (1)

[Claims] 1. A removal anchor method, wherein a step of arranging a PC steel material in a groove on a peripheral surface of a core, and a sheath is sheathed over at least a fixing length portion of the core and the PC steel material to manufacture an anchor. A step of inserting the anchor into the anchor hole, a step of filling the inside and outside of the sheath with a fixing material, and a step of tension-fixing the anchor. When filling the fixing material into the sheath, The removal anchor method is characterized in that the fixing material is pressed in the axial direction of the anchor.