JP2004232312A - Removal method for tension support material for anchor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a removal method for a tension support material for an anchor for shortening a construction period by shortening time up to extracting the tension support material by melting a covering material for covering the tension support material in a short time. <P>SOLUTION: This removal method for the tension support material for the anchor removes the tension support material 3 from the anchor 40 formed by fixing the tension support material 3 by injecting grout 4 into an anchor hole by inserting the tension support material 3 of a PC steel stranded wire into the drilled anchor hole 2 by drilling the anchor hole 2. The removal method of the tension support material for the anchor pulls and removes the tension support material 3 after heating and melting a resin film 5 by heating by impressing (6, 7 and 8) a low frequency on the tension support material 3 by forming the resin film 5 in an anchor body part L2 of the tension support material 3. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an anchor formed by drilling an anchor hole, inserting a tension support made of PC steel wire into the drilled anchor hole, and injecting grout into the anchor hole to fix the tension support. TECHNICAL FIELD The present invention relates to a method for removing a tension support for an anchor for removing the tension support for an anchor from the apparatus.
[0002]
[Prior art]
For example, it is well known to use anchors to support a retaining wall, and the tension supports used as tension supports in forming the anchors are to be removed after the work is completed. Various methods of removing the tension support member are known.
[0003]
Japanese Patent Application No. 2001-282775 discloses one of the methods for removing the tension support member for an anchor.
According to the "removal anchor method" of Japanese Patent Application No. 2001-282775, a step of inserting a tendon provided with a tension supporting material coated with a biodegradable material and an injection hose for injecting a material for biodegradation, The method includes a step of injecting a material for biodegradation from the injection hose after the injection material is solidified, and a step of withdrawing the tension support material from the ground.
More specifically, in the prior art disclosed in Japanese Patent Application No. 2001-282775, as shown in FIG. 6 of the accompanying drawings, a step of injecting water, acid, bacteria, and the like from inside a hose (step S21); It has a step (Step S22) in which the biodegradable plastic wound around the PC steel strand is melted, and a step (Step S23) in which a gap is formed between the injection material (eg, grout) and the PC steel strand is removed. ing.
[0004]
However, in the above-mentioned method, it takes time to decompose the biodegradable material coated on the tension support material in order to pull out the tension support material, and materials for inducing and promoting biodegradation are easily available. In some cases, there is a problem that the technique is required for handling and storing the material.
[0005]
[Problems to be solved by the invention]
The present invention has been proposed in view of the above-described problems of the related art, and shortens the time until the tension support is pulled out by melting the coating material coated on the tension support in a short time, thereby shortening the construction period. An object of the present invention is to propose a method of removing a tension support material for an anchor which can be shortened.
[0006]
[Means for Solving the Problems]
In the method for removing a tension support material for an anchor of the present invention, a hole is drilled in an anchor hole, and a tension support material of a PC steel strand is inserted into the drilled anchor hole; A grout (4) is injected into the anchor hole to fix the tension support (3), and the tension support (3) is removed from the anchor (40) formed by fixing the tension support (3). A resin film (5) is formed on the anchor body portion (L2) of the support material (3), and a low frequency is applied (7, 8) to the tension support material (3) to heat the resin film (5). It is characterized in that it is heated and melted, and then the tension support material (3) is pulled off and removed (Claim 1: First Embodiment).
[0007]
In the above method, the resin (5) applied to the PC steel strand (3) is melted by continuously applying (7, 8) low-frequency heating to the PC strand (3), Adhesion with grout is reduced, and it is easy to pull out the strand (3) from the PC steel. If the resin (5) applied to the PC steel strand (3) is an epoxy resin, it melts at about 200 ° C.
If the resin (5) solidifies again unless low frequency is continuously applied, the PC steel strand (3) is pulled out with the removing jack (9) while applying low frequency. Good.
[0008]
Here, in the free length portion (L1), all the PC steel strands are covered so as to be surrounded by the sheath material (10), and the inside of the cover of the sheath material (10) is covered with the grout (4). Grease (12) or the like is filled so as not to enter the material (10).
With such a configuration, when a low frequency is applied, the free length portion (L1) is also heated. When the free length portion (L1) is heated, the viscosity of the grease (12) inside the sheath material (10) decreases, and the resistance decreases, so that the pull-out resistance of the free length portion (L1) also decreases. Accordingly, the removal of the PC steel strand from the anchor hole is performed quickly and easily, and the cost is reduced.
[0009]
When the sheath material (10) is made of cardboard or the like, the sheath material (10) such as cardboard is heated by the PC steel strand (3), and the sheath material (10) is carbonized. Easy to pull out.
[0010]
If the frequency to be applied is high, there is a duty to report, but if the frequency is low, there is no such regulation and there is no restriction on the construction.
[0011]
In the present invention, unlike the conventional folding type anchor, the resistance of the folded portion does not occur, so that the tensile force is increased by about 20%, and even if an odd number of tension supporting members are used.
[0012]
In the method for removing a tension support member for an anchor of the present invention, a hole for an anchor hole (2) is drilled, and a tension support member (3) made of PC steel wire is inserted into the drilled anchor hole (2). And grout (4) is injected into the anchor hole (2) to secure the tension support (3) and to remove the tension support (3) from the anchor (40) formed by fixing the tension support (3). In the removal method, a resin film (5) is formed on the anchor body portion (L2) of the tension support member (3), and the tension support member (3) is heated (70, 80) by applying a current (70, 80) to the resin film (5). ) Is heated and melted, and then the tension support member (3) is pulled off to remove (claim 2: second embodiment).
[0013]
The tip (3b) of the tension support (3) is connected with a conductive material (14) (claim 3: second embodiment).
[0014]
Here, an even number of tension support members (3) are required, and the end (3a) of the first tension support member (3) on the air release side and the open end of the final tension support material (3) are opened. Side end (3a) is connected to a power supply (80) via a power supply line (70), and two adjacent underground ends (3b) or the atmosphere side end (3a) are conductive. Connected by the material (14), a continuous circuit-like circuit is formed.
When a direct current is passed through this circuit, heat is generated by the resistance of the tension support member (3) itself.
Accordingly, the resin film (5) coated on the tension support (3) is heated and melted by the heat generation, and the tension support (3) can be easily pulled and removed.
[0015]
In addition, an AC power supply (85) is used as a power supply, and the AC power supply (85) is connected to the end (3a) of the tension support member (3) on the atmospheric side, and the underground side of the tension support member (3) is connected. The end (3b) is grounded (E) with the ground (G), so that each tension support member (3) is energized, and heat is generated by the electric resistance of each tension support member (3). By heating and melting the resin film (5) coated on the material (3), the tension supporting material (3) can be easily pulled and removed (third embodiment).
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
The first embodiment will be described with reference to FIGS.
[0017]
In FIG. 1, a retaining wall 1 is previously installed on a ground G.
[0018]
Next, an anchor hole 2 is drilled at a predetermined angle θ while penetrating the mountain retaining wall 1, and a plurality of tension support members 3 composed of PC steel strands are inserted into the anchor hole 2.
The anchor body portion L2 on the distal end side of the tension support member is coated with, for example, an epoxy resin film 5, and the free length portion L1 on the atmosphere side is coated with a sheath material 10 so as to surround all the tension support members 3. Have been.
[0019]
The inside of the sheath material 10 is filled with grease 12 so that the grout 4 does not enter the sheath 10.
[0020]
After the insertion of the plurality of tension supporting members 3 into the anchor holes 2 is completed, the grout 4 is injected into the space where the anchor holes 2 remain, and the grout 4 starts to solidify.
[0021]
When the grout 4 has reached a certain degree of hardness, anchoring is performed.
When the support function of the anchor becomes unnecessary, the PC steel strand removal jack 9 as shown in FIG. 2 is set so as to grip the vicinity 3a of the end of the PC strand 3 exposed to the atmosphere side. .
[0022]
Further, the end 3a of any one of the PC steel strands 3 is connected to the low frequency generator 8 via the conductive material 7.
[0023]
After the connection of the low frequency generator 8 to the end 3a of the PC steel strand 3 is completed, a low frequency is applied to the PC steel strand 3 from the low frequency generator 8 via the conductive material 7.
Reference numeral 6 in the drawing indicates a pedestal for angle adjustment.
[0024]
According to the first embodiment configured as described above, by continuously applying low-frequency heating to the PC steel strand 3, the resin film 5 applied to the PC steel strand 3 is melted, The strand 3 of PC steel is easily pulled out, and melts at about 200 ° C. if the resin 5 applied to the strand 3 of PC steel is an epoxy resin.
In the case where the resin 5 solidifies again unless the low frequency is applied, the wire 3 is drawn out from the PC steel with the removing jack 9 while applying the low frequency.
[0025]
On the other hand, in the free length portion L1 of the PC steel strand 3, all the PC steel strands are covered so as to be surrounded by the sheath material 10, and the inside of the cover of the sheath material 10 is filled with the grout 4 inside the sheath 10. The grease 12 and the like are filled so as not to enter. With such a configuration, when a low frequency is applied, the free length portion L1 is also heated. When the free length portion L1 is heated, the viscosity of the grease 12 inside the sheath material 10 decreases, and the resistance decreases, so that the pull-out resistance of the free length portion L1 also decreases.
[0026]
When the sheath material 10 is made of cardboard or the like, the sheath material 10 such as cardboard is heated by a PC steel wire, and the sheath material 10 is carbonized, so that the sheath material 10 is further easily pulled out.
[0027]
If the frequency to be applied is high, there is a duty to report, but if the frequency is low, there is no such regulation and there is no restriction on the construction.
[0028]
Also, unlike the conventional folded type anchor, the resistance of the folded portion does not occur, so the tensile force is increased by about 20%, and the odd number of PC steel strands 3 to be used (PC steel in the second embodiment described later) The number of twisted wires 3 is limited to an even number).
As described above, the wire 3 is easily pulled out of the PC steel, so that the construction period is shortened.
[0029]
The second embodiment shown in FIGS. 3 and 4 is an embodiment in which an even number of tension supporting members and a DC power supply are connected to a closed circuit, and a DC current flows through the closed circuit.
[0030]
FIG. 3 shows an embodiment in which two PC stranded wires 3 are inserted into the anchor holes 2.
In FIG. 3, as in the first embodiment shown in FIGS. 1 and 2, two tension support members (PC) made of PC steel stranded wires are drilled into the drilled anchor holes 2 while penetrating the retaining wall 1. Insert steel strand 3).
[0031]
The anchor body portion L2 on the distal end side of the tension support member 3 is coated with, for example, an epoxy resin film 5, and the free length portion L1 on the atmosphere side is coated with a sheath material.
The underground end portions 3b of the two tension support members 3 are connected to each other by a bridge 14 made of a conductive material, while the atmospheric end portions 3a of the two tension support members 3 are installed in the vicinity of the construction area on the atmospheric side. And a power supply line 70 to form a continuous circuit-like circuit.
When a direct current is passed through this circuit, heat is generated by the resistance of the tension supporting member 3 itself.
[0032]
FIG. 4 shows another embodiment in which four PC steel strands 3 are inserted into the anchor holes 2. Same as the first embodiment of FIGS. 1 and 2 except that the ends of adjacent PC steel strands are all connected in series by bridges 14 and the number of PC steel strands is increased from two to four. It is.
[0033]
As described above, the second embodiment shown in FIGS. 3 and 4 is configured to generate heat by the resistance of the PC steel strand 3 itself by passing a direct current through the closed circuit.
Accordingly, the resin film 5 coated on the PC steel wire 3 is heated and melted by the heat generation effect, and the tension supporting member 3 can be easily pulled and removed.
[0034]
Next, a third embodiment of the present invention will be described with reference to FIG.
In the second embodiment shown in FIGS. 3 and 4, a DC current is applied to the PC steel stranded wire to melt the resin film coated on the PC steel stranded wire by the heat generating action of the PC steel stranded wire, thereby forming the PC steel stranded wire. This is an embodiment in which removal from the anchor hole is easy.
On the other hand, in the third embodiment shown in FIG. 5, the resin film covering the PC steel strand is melted by the heating action of the PC steel strand by applying an alternating current to the PC steel strand, thereby forming the PC steel strand. This is an embodiment for facilitating removal from the anchor hole.
[0035]
In FIG. 5, as in the first embodiment shown in FIGS. 1 and 2, two tension support members (PC) made of PC steel stranded wires are drilled into the drilled anchor holes 2 while penetrating the retaining wall 1. Insert steel strand 3).
[0036]
The anchor body portion L2 on the distal end side of the tension support member 3 is coated with, for example, an epoxy resin film 5, and the free length portion L1 on the atmosphere side is coated with a sheath material.
The atmosphere-side ends 3a of the two tension support members 3 are connected in parallel to an AC power supply 85 installed near the construction area on the atmosphere side by a power supply line 75, while the two tension support members 3 are underground. Both ends 3b are grounded to the ground G.
When an alternating current is passed through the two tension support members 3, heat is generated by the resistance of the tension support members 3 themselves.
[0037]
As described above, since the AC power supply 85 is used in the third embodiment, the power supply line (parallel) 75 only needs to be connected to the atmospheric side end of the PC steel strand 3, thereby simplifying the apparatus. .
In addition, in FIG. 5, the code | symbol "E" shows the earth line on the underground side.
[0038]
It is to be noted that the illustrated embodiment is merely an example, and is not intended to limit the technical scope of the present invention.
[0039]
【The invention's effect】
The functions and effects of the present invention are listed below.
(1) By continuously applying low-frequency heating to the tension support, the resin applied to the tension support is melted, and the tension support is easily pulled out.
(2) The grease inside the sheath material covering the tension support material is also heated when a low frequency is applied, so that the viscosity of the grease decreases, and the resistance decreases, so the pull-out resistance of the tension support material also decreases. I do.
(3) As a result of (1) and (2), the tension support material can be quickly removed from the anchor hole, and the construction period and cost can be reduced.
(4) When the sheath material is made of cardboard or the like, the sheath material such as cardboard is heated by the tension supporting material, and the sheath material is carbonized, which makes it easier to pull out the sheath material.
(5) Since the frequency to be applied is low, there is no regulation such as notification, and there is no restriction on construction.
(6) Unlike the conventional folded type anchor, the resistance of the folded portion does not occur, so the tensile force is increased by about 20%, and unlike the DC power supply specification in which the tension support material used is limited to an even number, An odd number is possible.
(7) The DC power supply and the tension supporting member are connected to a closed circuit, and a DC current flows through the closed circuit, so that the tension supporting member generates heat by its own resistance. Therefore, the resin film coated on the tension supporting material is heated and melted by the heat generation effect, and the tension supporting material can be easily pulled and removed.
(8) When an AC power supply is used as the power supply for energizing the tension support, the underground end of the tension support is grounded without any connection, so that the device can be simplified. Can be
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a configuration before a low-frequency generator is connected in a first embodiment of the present invention.
FIG. 2 is a sectional view showing a configuration of a main part according to the first embodiment of the present invention.
FIG. 3 is a cross-sectional view showing the entire configuration of an example of the second embodiment of the present invention.
FIG. 4 is a sectional view showing the overall configuration of another example of the second embodiment of the present invention.
FIG. 5 is a cross-sectional view illustrating the entire configuration of a third embodiment of the present invention.
FIG. 6 is a process diagram showing, in a flow chart, a step of removing a tension support member for an anchor according to a conventional technique.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Mounting wall 2 ... Anchor hole 3 ... Tension supporting material / PC steel strand 4 ... Grout 5 ... Resin film 6 ... Angle adjustment base 7 ... Conductive material 8 ... Low frequency generator 9 ... Removal jack 10 ... Sheet material 12 ... Grease L1 ... Free length L2 ... Anchor body G ... Ground mountain E ... Earth line

Claims (3)

An anchor hole is drilled, a tension support of a PC steel strand is inserted into the drilled anchor hole, and grout is injected into the anchor hole to fix the tension support. In the method of removing the tension support for the anchor for removing, a resin film is formed on the anchor body portion of the tension support, a low frequency is applied to the tension support, and the resin film is heated and melted. Next, a tension supporting material is removed by pulling the tension supporting material. An anchor hole is drilled, a tension support of a PC steel strand is inserted into the drilled anchor hole, and grout is injected into the anchor hole to fix the tension support. In the method of removing the tension support for the anchor for removing the resin, a resin film is formed on the anchor body portion of the tension support, and the tension support is heated by being energized, the resin film is heated and melted, and then the tension support is formed. A method for removing a tension support material for an anchor, wherein the material is pulled and removed. 3. The method according to claim 2, wherein the distal ends of the tension supporting members are connected by a conductive material.

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