JPS611725A - Method and anchor for removing tension member - Google Patents

Abstract

PURPOSE:To very easily remove anchors by a method in which tension members are pulled toward a cavity and bundled, and then the tension members are separated and removed while being distorted. CONSTITUTION:A synthetic fiber rope 1 buried in the central part of an anchor body 7 is pulled to form a cavity 8 in parallel with a steel wire 2 in the central part. The wire 2 is then pulled toward the cavity 8 to separate the wire 2 from a hardener 6 with small forces. Several steel wires 2 are bundled and distorted for integration, the steel wire 2 in the end portion 7a of the anchor body 7 is separated from the hardener 6 by further distortion, and all the steel wires 2 are pulled out. Tension members can thus be safely and exactly recovered, the removing operation of the tension members is made easier, and the cavity can be exactly and easily formed.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field of the Invention The present invention relates to a construction method and a removal anchor that make it possible to remove tension members when unnecessary.

(if) Background of the technology Anchors, by their nature, must be installed at a distance from the structure, and their presence may interfere with the construction work of other structures, or their installation is only allowed during construction work. This often has to be removed.

For this reason, it is expected to develop an anchor that can be easily removed when unnecessary, and whose construction is not complicated by making removal easy.

(c) Conventional technology and problems Conventionally, when constructing an anchor, a steel rod whose surface was coated with grease or the like to form a surface film was temporarily buried inside the anchor, and when the anchor was no longer needed, this was done. The anchor was pulled out and gunpowder was poured into the hole left behind to destroy the anchor, or water, oil, etc. were injected under pressure to split the anchor, and the tensile material was pulled out and removed. -8251
issue).

However, when using this method to inject water, oil, etc. under pressure, the entire length is not destroyed at the same time, and the hardenable material is locally destroyed and the water, oil, etc. Because the fluid leaked from that area and the pressure decreased, it was not possible to destroy it along its entire length. In addition, the temporarily buried steel rod must first be pulled out, but the steel rod may become fixed to the anchor due to the surface film, and it is difficult to say that it can be easily removed.

The example shown in FIGS. 8 and 9 is an improved version of this means, which is currently commonly used (Japanese Patent Publication No. 54-22007).

This example is characterized by using a hollow material a.

The anchor is formed by pouring a hardening material d such as mortar cement into a hole C dug in the ground. Tensile members e connected directly or indirectly to earth banks and structures are p
Cll rods or steel cables are used and are placed in the drilled hole C before the hardenable material d is cast, or inserted into the hardenable material d after the hardenable material d is cast but before it hardens. equipped by. The hollow member a is installed by the same means as the tensile member e. A plug f is provided at the lower end of the hollow #a to prevent the curable material d from flowing into the hollow #a. The tensile material e and the hollow material a are generally installed at the same depth in the hole C, but due to the anchoring strength of the curable material d, the hollow material a is shallower than the tensile material e. In some cases, you can get away with it.

To remove this anchor, put a disabling agent such as gunpowder into the hollow member a and destroy the hardenable material d by explosion or the like to reduce the fixing force of the hardenable material d to the tensile member e.
The tensile material e is pulled out and removed using a jack or the like.

According to this means, the work of pulling out the temporarily buried PC steel rod is omitted, and there is an advantage that the removal work can be performed extremely easily.

However, since gunpowder or the like is used to reduce the fixing force of the curable material d to the ridge material e, the work is dangerous, and when the curable material d is broken, the tensile material e
In some cases, the tensile material e may be damaged, making it difficult to completely pull out the tensile material e.

The present invention has been made in view of the problems of the prior art described above, and its purpose is to replace the method of destroying the anchor body and removing the tensile material. The purpose of this method is to remove the tensile material by peeling it off while twisting it toward the cavity formed in the center of the anchor body.

(G) Structure of the Invention In order to achieve the above object, the first invention of the present invention is to provide an anchor trunk by disposing a plurality of tensile members in a hole dug in the ground and casting a hardening material. creating a body, and forming a cavity in the anchor body at the time of creating the anchor body or removing the tension member, forming a cavity parallel to the tension member and closer to the center than the tension member, and when removing the tension member, After the tensile material is drawn in the direction of the cavity and bundled, the tensile material is peeled off while being twisted.
When a plurality of tensile materials are placed in a hole dug in the ground and a hardening material is cast, a temporary burial body for removal processing is placed in the hole in parallel with the tensile materials. In the anchor, the temporary buried body is made of a material that has low adhesion to the curable material.

(F) Embodiments of the Invention Hereinafter, embodiments of the present invention will be described based on FIGS. 1 to 6.

First, as shown in FIG. 7, for example, several steel wires (12, 7
A tensile structure 4 is prepared in which 4 to 8 mm diameter (6 in this example) 2 are arranged at equal intervals and fixed with tape 3 at arbitrary intervals. This tensile structure 4 is
Similar to normal anchor construction, the anchor is inserted into a prepared hole 5 drilled at a predetermined depth and casting angle, and a cement paste made of, for example, early-strength cement is injected as a hardening material 6, and the first
The anchor body 7 is shown in the figure and the second WJ.

Next, the steps to be taken when it becomes necessary to remove the steel wire 2 from the anchor thus constructed will be described.

First, the polyethylene synthetic fiber rope l buried in the center of the anchor body 7 is pulled out. The polyethylene synthetic fiber rope 1 does not adhere to the curable material 6 and the steel wire 2, so when it is pulled, the synthetic fiber rope itself stretches several tens of percent and can become small in diameter. It can be easily removed and no debris remains in the formed cavity.As a result, a cavity 8 is formed in the center of the anchor body 7 parallel to the steel wire 2, as shown in FIG. The steel wire 2 is present around the side wall of the cavity 8.

In the state shown in FIG. 3, in order to peel off the adhesion between the steel wire 2 and the hardenable material 6 and remove the steel wire 2, the steel wire 2 is pulled toward the cavity 8 located in the center. The adhesion between 2 and the curable material 6 can be peeled off with a small force.

In order to generate such a force that moves the steel wires 2 in the radial direction of the cavity 8, several steel wires 2 are twisted into one bundle as shown in FIGS. 4 and 5. As a result, the steel wire 2 is inserted into the cavity 8 at the end 7a of the anchor body 7.
It can generate a force that draws you to the side. Furthermore, the force increases by twisting, and the anchor body 7
The steel wire 2 and the curable material 6 at the end portion 7a of the steel wire 2 are separated from each other.

If this state continues, the peeling due to twisting will progress in the depth direction as shown in FIG. 6, and will eventually reach the end of the steel wire 2, and all peeling will be completed. Thus, all steel wires 2
can be pulled out.

In the above embodiment, the polyethylene synthetic fiber rope 1 was used as a temporary burial body when constructing the anchor, but the rope is not limited to this. Steel wire (tensile material) 2 and hardening material (mortar) 6
Any material may be used as long as it has a small adhesion to the material. Furthermore, a synthetic resin foam may be used as the temporary buried body.

Although it is difficult to form a complete cavity in a synthetic resin foam like the polyethylene-based synthetic fiber rope mentioned above, it is extremely easily destroyed by the tensile material that is twisted, and the tensile material progresses in the depth direction. It does not impede movement and poses no obstacle to implementing the present invention. Furthermore, the present invention can also be applied to ordinary anchors in which a cavity is formed in the center of the anchor body using a drilling machine or the like during removal.

(G) As described in detail, according to the present invention, the tension member is easily peeled off from the curable material by simply being twisted toward the center of the cavity during removal, thereby breaking the anchor body.

Compared to the construction method in which the tensile material is removed by breaking it, the tensile material can be recovered safely and reliably, and the removal work of the tensile material becomes easier. Moreover, since the cavity formed in the anchor trunk body is formed by the temporary burial body made of a material with low adhesion between the tensile material and the curable material, the cavity can be formed reliably and easily.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional view of the removal anchor according to the present invention, Fig. 2 is a plan view thereof, Figs. 5 is a plan view of FIG. 4, FIG. 6 is a longitudinal sectional view showing the peeled state of the tensile material, and FIG. 7 is an end view of the tensile structure in this example. FIG. 8 is a plan view of a conventional removal anchor, and FIG. 9 is a longitudinal sectional view thereof. 1... Polyethylene synthetic fiber rope (temporary burial body), 2... Steel wire (tensile material), 3... Tape, 4...
- Tensile structure, 5... Creation hole, 6... Curable material,
7... Anchor trunk body, 8... Hollow. Fig. 1 Fig. 8 Fig. 2 Fig. 6 Fig. 4 Fig. 5 Fig. 8-9] Fig. 7\C d

Claims (4)

[Claims] (1) Create an anchor body by placing multiple tension members in a hole dug in the ground and pouring a hardening material,
Further, a cavity is formed in the anchor body at the time of creating the anchor body or removing the tension member, and a cavity is formed parallel to the tension member and closer to the center than the tension member, and when removing the tension member, the tension member is A tensile material removal method characterized by pulling the tensile material toward a cavity and bundling it, and then peeling off the tensile material while twisting the material. (2) When placing a plurality of tensile materials in a hole dug in the ground and placing a hardening material, a temporary buried body for removal processing is placed in the hole parallel to the tensile materials. A removal anchor characterized in that the temporary burial body is made of a material that has a low adhesion to a curable material. (3) The removable anchor according to claim 2, wherein the temporary buried body is a polyethylene synthetic fiber rope. (4) The removal anchor according to claim 2, wherein the temporary buried body is a synthetic resin foam.