JP2008088772A - Device for removing high frequency induction heating anchor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for removing a PC steel stranded wire surely at a low cost and in a short time, and to provide a device for it. <P>SOLUTION: The device comprises a high frequency induction coil 10 wound to have a cylindrical shape with a predetermined diameter for covering the outer periphery of one or a plurality of unbonded PC steel stranded wires 1 connected and fixed to a load-bearing body, a lead wire 11 connected to a coil terminal 10c of the high frequency induction coil, and a high frequency power supply device 12 generating a high frequency current of a predetermined frequency applied to the high frequency induction coil by the lead wire. When the unbonded PC steel stranded wires are removed from the ground after construction work, the lead wire 11 is connected to the high frequency power supply device 12, the high-frequency current is applied to the high frequency induction coil 10, the PC steel stranded wires are heated by the induction current generated in the unbonded PC steel stranded wires 1 positioned in the high-frequency induction coil, and the unbonded PC steel stranded wires 1 in a state of tension are cut. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a PC (pressed concrete) steel strand removal device for anchors in construction work.

  2. Description of the Related Art Conventionally, in construction work such as earth retaining, a removable anchor that does not leave a tensile steel material such as unbonded PC (pressed concrete) steel stranded wire in the soil after construction is widely known.

  Patent Document 1 discloses a core removal removal method in which a plurality of unbonded PC steel stranded wires are bundled together. In the present invention, in order to solve the problem when a plurality of unbonded PC steel stranded wires are conventionally drawn and a space for cutting the fixed PC steel stranded wire is secured, an unbonded large-diameter steel material is used as a flexible spacer. Cover the anchoring part of the anchor placed in the cylinder with PC steel stranded wire from which multiple unbonding processes have been removed to form the fixing part, and then pull out the central large-diameter steel material after construction, and fix the fixed PC steel stranded wire. Edges are cut by the drawn gaps to facilitate removal from the ground.

  In this method, a large-diameter removal space can be secured, so there is a merit that the fixing surface can be cut with a relatively small tensile force. However, since a large-diameter unbonded PC steel material is used, there is a problem that the material cost increases. .

  Further, in Patent Document 2, an unbonded PC steel stranded wire is inserted into an anchor hole by making a U-turn with a load-bearing body, and filled with a grout material (a cemented material such as cement milk). PC steel stranded wire is fixed in the ground, both ends of unbonded PC steel stranded wire are tensioned and fixed under a predetermined load from outside the hole, and the removal type that supports the retaining wall and retaining wall by the tension and fixing force Anchors are described as prior art. In this unbonded PC steel stranded wire U-turn system, the ground fixing tool is removed after construction, and one end of the unbonded PC steel stranded wire is unbonded via a U-turn portion by pulling it with a jack or a tow. PC steel stranded wire is pulled out and removed.

  In this method, although the sheath tube is filled with lubricating oil, there is a problem that the friction coefficient at the U-turn portion of the PC steel stranded wire is high and cannot be extracted without using a certain large force. In addition, there is a problem that the U-turn portion is not twisted due to deformation such as twisting and cannot be pulled out.

  As a solution to these problems, Patent Document 3 is an invention of a method and an apparatus capable of removing a PC steel twisted wire reliably and in a short time regardless of the mooring method with a load-bearing body. A liquid-tightly sealed negative electrode facing the PC steel stranded wire from which the sheath has been removed is provided on the embedded tip side, and after construction work, the electrolyte solution is circulated through the negative electrode, and a DC power source is connected to the PC steel stranded wire. The anode is connected to the cathode and the cathode is applied with a voltage, and the PC steel twisted wire is melted and cut to be able to be drawn.

  However, this method has the advantage that it can be removed reliably without restrictions on installation compared to the conventional technology, but requires a water tank for the electrolyte solution, a liquid feed pump, and a pipe for the liquid feed pipe. There was a problem that it was large and costly.

  Further, Patent Document 4 includes a coil that encloses a tension member in a tubular shape at a cutting position, and electrical energy of a frequency of 5 to 30 KHz and a voltage of 500 to 800 V are applied to the coil to cause an eddy current in the tension member. An apparatus for cutting a tension member of an anchor to be cut by heating at a predetermined position is disclosed. However, in order to generate the necessary heat, in addition to the coil as the primary winding, it is necessary to provide a highly heat-resistant thermal buffer layer and a paramagnetic tubular core (supporting tube 7) that generates a secondary induced current. There was a complicated structure.

Patent Document 4 will be described in further detail below. In paragraph 7 of this specification, “... a coil that is surrounded by a cutting position of the tension member and that is supplied with an electric current for generating heat by induction in one or a plurality of tension members. (See Swiss Patent No. 603919 (Patent Document 5)) In this case, most of the supplied heat is already pulled by heat conduction even though a thermal buffer layer is provided. It has been found that because the member itself is moved, it is not possible to obtain a temperature sufficient to reliably cut the tension member. "
That is, Patent Document 4 requires a configuration of the supporting tube body 7 (see FIG. 1) having a predetermined length in order to solve the problem. The supporting tube 7 does not conduct heat in the axial direction of the tension member, and the temperature is stored only in the supporting tube 7.

Japanese Patent Laid-Open No. 9-41371 (2nd, 3rd page, 1st and 2nd figures) Japanese Patent Application No. 2002-97638 (2nd page, FIGS. 4 and 6) Japanese Patent Application No. 2005-180001 (2nd page, FIG. 1) Japanese Patent No. 3163207 (page 2, FIG. 1) JP-A-6-158656 (Swiss Patent No. 603919)

  The present invention has been made in view of the above problems, and does not require the thermal buffer layer and the supporting tube body, and is a PC steel twist that can be reliably and reliably constructed with a high-frequency induction coil at low cost and in a short time. It is an object of the present invention to provide a line removing device.

  It is another object of the present invention to provide a device capable of simultaneously cutting and removing a plurality of unbonded PC steel stranded wires connected and fixed to a load bearing body simultaneously with a single removing device.

In order to solve the above-mentioned problems, the high-frequency induction heating anchor removing device of the present invention fixes the PC steel stranded wire end to the embedded distal end side of the unbonded PC steel stranded wire covered with the synthetic resin sheath, and connects to it. An earth anchor that includes a load carrying body, embeds the load carrying body in a hole in the ground, injects a caking material into the hole to form an anchor fixing portion, and tensions the proximal end of the PC steel stranded wire on the ground side PC steel strand removal device in construction work used as a
The PC steel stranded wire is composed of a single strip or a plurality of strips, and the load bearing body reliably forms a fixed connection by injection of the solidified material to the respective strips, so that the strips or holes into which the respective strips are inserted, and
Each filament inserted and set in the filament groove or hole is wound in a cylindrical shape along the filament direction so that all the filaments for induction heating with a high frequency magnetic field are located on the inner peripheral side. High frequency induction coil,
A high-frequency current input / output terminal for applying a high-frequency current to the high-frequency induction coil from a high-frequency power supply device installed on the ground side through a twisted power supply line;
A high frequency resonance current having a resonance frequency f ₀ (1 / 2π (Ls · Cs) ^1/2 ) determined from an inductance Ls of the high frequency induction coil and a series capacitance Cs of an adjustment capacitor incorporated in the high frequency power supply device is induced. In a short time, the amount of heat flowing in the coil direction is reduced by maximizing the secondary induced current of the eddy current induced in the circumferential direction of each filament on the cylindrical inner circumference side of the coil. It is characterized by minimizing the breaking time of the strip.

Further, the secondary induced current induced in the circumferential direction of each filament due to the change of magnetic flux in the high-frequency induction coil has a higher current density on the surface of each filament due to the skin effect. The resonance frequency f ₀ is operated in a high range of at least 20 KHz or more so that the power supplied from the apparatus is concentrated more than the surface side.

Moreover, the high frequency induction heating anchor removing device of the present invention comprises a plurality of unbonded PC steel stranded wires covered with a synthetic resin sheath, and the PC steel stranded wire ends are crimped onto the end of the PC steel stranded wire. A plurality of load-bearing bodies fixed to and coupled to the
These load-bearing bodies are buried in a plurality of locations in the hole in the ground, and a fixing material is injected into the hole to form a plurality of anchor fixing portions, and the base ends of these PC steel stranded wires are tensioned on the ground side. A device for removing those PC steel stranded wires in construction work used as an earth anchor,
In order to reliably form a fixed connection by injecting the solidified material to the PC steel stranded wires divided in advance for each load-bearing body, the load-bearing bodies have a plurality of filament grooves or holes inserted into the respective filaments. When,
Each of the plurality of load-bearing bodies is provided on each of the plurality of load-bearing bodies, and each of the filaments inserted and set in the filament groove or hole is induction-heated with a high-frequency magnetic field. A high-frequency induction coil wound in a cylindrical shape along
All the input / output terminals of the high-frequency induction coil provided on the load-bearing body are connected in series, and the high-frequency induction coil is connected to the high-frequency induction coil from a high-frequency power supply device installed on the ground side via a twisted power supply line. A high-frequency current input / output terminal for applying a high-frequency current,
Resonance frequency f ₀ (1 / 2π {(L ₁₎ determined from the inductances L 1 _, L ₂ ,... Of the plurality of high-frequency induction coils and the series capacitance Cs of the adjustment capacitors incorporated in the high-frequency power supply device. + L ₂ ...) Cs} ^1/2 ) is caused to flow through the induction coil, and is an eddy current 2 that is induced in the circumferential direction of each filament on the cylindrical inner peripheral side of the coil. It is characterized in that the next induced current is maximized and the breaking time of the filament is minimized within a short time when the amount of heat flowing in the wire diameter direction is small.

In the configuration of the present invention, a high-frequency current having a resonance frequency determined by a high-frequency induction coil and a capacitor with a built-in high-frequency power source is passed through the coil, and the secondary induction current is maximized on the surface of each PC steel stranded wire surrounded by the coil. Therefore, the PC steel stranded wire rises in temperature and breaks in a short time. Since the current is large and the time is short, the amount of heat flowing in the wire direction from the PC steel stranded wire itself is reduced, and the need for a supporting tube is eliminated.
Furthermore, by increasing the resonant frequency f _0, the more the secondary induced current due to the skin effect temperature rise of the same time by increasing the density of the surface side is increased, thereby cutting the PC steel twisted wire in a shorter time.
Therefore, since this structure does not require a supporting tube, the structure is simplified and the manufacturing cost is reduced. In addition, it is not necessary to consider a structure such as a waterproof filling such as polyurethane foam or a mortar, or a packing for preventing the intrusion of a consolidated material in an intermediate region between the carrier tube and the PC steel stranded wire.

  In addition, the efficiency of heat generation is good in the supporting tube, but if the generated heat is not conducted and transmitted to the PC steel stranded wire inside it, the efficiency is lowered. However, it is not necessary to pay such consideration because the heat generation source of the configuration of the present invention is in the PC steel stranded wire itself.

  According to the present invention, the PC steel stranded wire main body in a state in which the PC steel stranded wire main body is directly heated by the induced current due to the high frequency current flowing in the high frequency induction coil at the embedded distal end side of the anchor and preloaded by the tension with the ground. The cross-sectional area of is reduced and cut. For this reason, the cut PC steel stranded wire body is reliably separated from the load-bearing body, and the tip of the load-bearing body is not U-turned, so it can be smoothly used without using a powerful pulling equipment such as a jack or a crane. And it can be pulled out and removed reliably. For this reason, it is possible to prevent the problem of being left in the ground due to the inability to pull out.

  Moreover, since the heat is generated by an induction current generated from a magnetic flux generated at a high frequency due to the high frequency of the induction heating coil, the unbonded PC steel twisted wire is not required to be processed. A plurality of unbonded PC steel stranded wires penetrating the inside of the coil can be simultaneously heated to be cut at a desired position. For this reason, the construction time can be completed in several tens of seconds, the work period can be shortened significantly, and the anchor removal that conventionally had to be expected to some extent can be completed immediately on the spot at any time. it can.

  Further, an unbonded PC steel stranded wire may be inserted into a groove or a hole provided in the load-bearing body through a load-bearing body provided with a cylindrical high-frequency induction coil, and the load-bearing body provided with the high-frequency induction coil may be disposed at a planned cutting portion. Therefore, since it can be easily installed at the tip of the anchor (immediately after the load-bearing body), most of the underground PC steel stranded wire can be recovered and removed on the ground, and underground residues are kept to a minimum. be able to. The same applies to a plurality of load bearing bodies. When there are a plurality of load-bearing bodies, there is an effect of increasing the tension as an earth anchor and ensuring the construction.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. 1, FIG. 2 and FIG. 3 are schematic views showing the configuration of the high-frequency induction heating anchor removing apparatus according to the first embodiment of the present invention.

  The high frequency induction heating anchor removing apparatus of the present invention includes a cylindrical high frequency induction coil 10, a lead wire 11 extending from both ends of the high frequency induction coil 10, and a high frequency power supply device 12 that supplies a high frequency current to the lead wire 11. Composed.

  In order to use the high-frequency induction heating anchor removing device of the present invention, first, a plurality of unbonded PC steel stranded wires 1 whose tips are fixed to the load-bearing body 2 penetrate the coil inner peripheral side of the high-frequency induction coil 10. Before the load bearing body 2 and the unbonded PC steel stranded wire 1 are fixed by injecting the binder, one bundle of the unbonded PC steel stranded wire 1 is inserted into the high frequency induction coil 10 and arranged immediately after the load bearing body 2. Set it up.

  Next, the unbonded PC steel stranded wire 1 to which the high frequency induction coil 10 is attached together with the load bearing body 2 is inserted into the anchor hole 5 drilled in the ground. At that time, the lead wire 11 of the high-frequency induction coil 10 is extended to the ground, and a solidifying agent (groud) 6 is poured and solidified to form an anchor fixing portion.

  Next, a predetermined tension is applied to the unbonded PC steel stranded wire 1, and the unfixed PC steel stranded wire 1 is fixed to the fixing metal fitting 4 that holds the ground retaining wall 3. Proceed with construction work in a space anchored by anchors.

  After the construction work, the high frequency power supply device 12 is installed on the ground, the lead wire 11 is connected to the output terminal of the high frequency power supply device 12, and a high frequency current is applied to the high frequency induction coil 10 in the ground.

  A high-frequency magnetic flux is generated in the PC steel stranded wire by the high-frequency current passed through the high-frequency induction coil 10, and this magnetic flux passes through the unbonded PC steel stranded wire 1, thereby causing secondary induction current in the circumferential direction of the PC steel stranded wire. Joule heat is generated in the unbonded PC steel stranded wire 1 and heated rapidly, and the unbonded PC steel stranded wire 1 in a tension state is cut.

  Finally, the fixing bracket 4 is removed, and the unbonded PC steel stranded wire 1 cut at the tip is pulled out from the ground.

  FIG. 2 is a cross-sectional view illustrating an arrangement state of the first embodiment (one stage of load bearing body) of the high-frequency induction coil 10 of the present invention.

  The unbonded PC steel stranded wire 1 is inserted into the load-bearing body 2, and the tip is fixed with a wedge 2a. In this figure, four unbonded PC steel stranded wires 1 are fixed to a load-bearing body 2. In FIG. 2, only the front two are shown.

  The high frequency induction coil 10 is arranged immediately after the load bearing body 2 in a state where the unbonded PC steel stranded wire 1 is inserted inside the coil.

  3 is a cross-sectional view of the high-frequency induction coil 10 attached to the unbonded PC steel stranded wire 1. FIG. 3A is a cross-sectional view taken along the line AA of FIG. 2, and FIG. 3B is a case of only one unbonded PC steel stranded wire. FIG.

  As shown in FIG. 3A, in this embodiment, four unbonded PC steel stranded wires 1 are penetrated inside the high frequency induction coil 10. In this embodiment, the case of four strips is shown, but a larger number of strips may be used.

  Moreover, as shown in FIG.3 (b), you may provide the high frequency induction coil 10 for every unbonded PC steel strand. For example, when a plurality of load-bearing bodies 2 are arranged in the anchor fixing portion, when it is desired to cut the unbonded PC steel stranded wire 1 fixed to the load bearing bodies 2 in the second and subsequent stages, high-frequency induction coils are individually attached to each one of the strips. . This embodiment (second embodiment) will be described with reference to FIGS. 6, 7, and 8. FIG.

  In FIG. 3, 10c is a coil terminal, 1a is a PC steel stranded wire, and 1b is a synthetic resin sheath covering the PC steel stranded wire 1a.

  FIG. 4 is a cross-sectional view of the high frequency induction coil 10 according to one embodiment of the present invention. As shown in the figure, the high-frequency induction coil 10 is a 600V vinyl (rubber) insulated electric wire having a cross-sectional area of 5.5 mm 2 to 8.0 mm 2 and is formed into a cylindrical shape from 10 ends to 20 ends, and a coil terminal 10c is provided at the coil end. The structure is such that the coil shape is prevented from collapsing by winding an insulating coating such as an adhesive vinyl tape around the coil. Note that the lead wire 11 has a twist configuration to cancel the influence of inductance.

  Next, the relationship between the high frequency induction coil 10 and the high frequency power supply device 12 will be described.

A high frequency resonance having a resonance frequency f ₀ (1 / 2π (Ls · Cs) ^1/2 ) determined from an inductance Ls of the high frequency induction coil 10 and a series capacitance Cs of a variable adjustment capacitor built in the high frequency power supply device 12. A current can be passed through the induction coil 10 to maximize the secondary induced current induced in the circumferential direction of each filament on the inner circumferential side of the coil cylinder. (See Figure 5)

In FIG. 5, when the coil 10 has Ls = 13.9 μH and the adjusting series capacitance Cs = 4.8 μF, the resonance frequency f _{0 is} about 20 KHz, and experimental data of the example at that time is shown. The PC steel stranded wire is an experimental example in the case of four strips.

  The horizontal axis represents the frequency f (KHz) of the output high-frequency current of the high-frequency power supply device 12, and the vertical axis represents the high-frequency current (A) / break time (S) at that frequency f and the reciprocal of the impedance of the resonance circuit (1 / Ω). .

  In FIG. 5, when f is 20 KHz, the secondary induced current can be maximized by resonating.

Utilizing the skin effect, flow as much current as possible near the surface of the PC steel stranded wire within the same time to raise the temperature of the metal surface in a short time (to reduce the heat flow in the direction of the PC steel stranded wire) because) the inductance Ls of the high frequency induction coil 10 in order to facilitate the breakage of the PC steel twisted wire, and to a smaller value may be a high frequency resonance frequency f ₀ (e.g., 50KHz or more).

  Next, a second embodiment of the high frequency induction heating anchor removing apparatus of the present invention will be described with reference to FIGS.

  Each of the second examples shows a case where there are a plurality of load bearing bodies. In the figure, reference numerals 21 and 22 denote first and second load bearing bodies, respectively. Reference numerals 23 and 24 respectively denote first and second heating coils, both of which are the high-frequency induction coil 10 having the structure shown in FIG.

  Reference numerals 25 and 26 denote first and second crimping grips, respectively. Reference numerals 27 and 28 denote tip caps.

  In this embodiment, the PC steel stranded wire is composed of six lines as shown in the detailed view of FIG. 7, and the three lines pass through the auxiliary bearing plate 21b and the bearing plate 21a of the first load-bearing body 21b, respectively. The front end of the auxiliary pressure plate 21 is crimped to the first pressure-bonding grip 25 and fixed so that the three strips do not move in the linear direction, and then the auxiliary pressure plate 21b, the pressure plate 21a, and the tip cap 27 are integrally fixed with three sets of fixing bolts.

  The second load-bearing body 22 passes through the grooves of the auxiliary bearing plate 22b and the bearing plate 22a in all six strips, and only the three strips to be fixed to the second load-bearing body 22 are crimped by the second crimping grip 26. It fixes so that it may not move to a direction, and the remaining 3 strips are connected to the following 1st load bearing body 21. FIG.

  Each of the bearing plates 21a and 22a and the auxiliary bearing plates 21b and 22b has friction rods 21c and 22c at the center thereof, and is sufficiently bonded and fixed when the binder is injected.

  Each of the bearing plates 21a, 22a is a friction rod 21c, 22c of a predetermined length, and when fixed by the three sets of fixing bolts, the interval between the bearing plate and the auxiliary bearing plate is maintained at a predetermined length. First and second heating coils 23 and 24 are provided, respectively.

  As shown in FIG. 7, the second heating coil 24 is surrounded and cylindrical so that only three strips of PC steel stranded wire fixed to the second load-bearing body 22 are on the inner peripheral side. The second heating coil 24 is wound around.

  Further, the remaining three strands of PC steel stranded wire are outside the second cylindrical heating coil 24 in the second load-bearing body 22 and are not induction-heated.

FIG. 8 illustrates the resonance frequency f _{0 in} the case of the two-stage first and second load bearing bodies 21 and 22. When the inductances of the first and second load bearing bodies 21 and 22 are L ₁ and L ₂ , the resonance frequency f ₀ is (1 / 2π {(L ₁ + L ₂ ) Cs} ^1/2 ). The values of L ₁ and L ₂ should be the same as much as possible. Due to the high frequency resonance frequency, the total 6 PC steel stranded wires of the first and second load bearing bodies 21 and 22 are simultaneously heated and fractured.

  FIG. 9 shows a preferred embodiment of the high-frequency induction overheat anchor removing device according to the present invention. In order to prevent the heating coil from being damaged when the drilling casing is pulled out when the anchor is installed, the first and second load bearing bodies are used. The coil protection tube 29 is covered so as to cover the outer peripheries of 21 and 22. The coil protective tube 29 is a tube in which a plurality of opening windows 29a are formed on the cylindrical side surface so that the caking agent 6 (groud) that is poured to fix the anchor flows into the coil arrangement portion and is fixed. Use. The material of the coil protection tube 29 is not limited to metal as long as it has a predetermined strength, and other materials may be used.

It is a schematic diagram which shows the structure of the removal apparatus of the PC steel twisted wire of this invention. It is sectional drawing explaining the arrangement | positioning state of the high frequency induction coil of this invention. It is sectional drawing of the high frequency induction coil 10 with which the unbonded PC steel twisted wire 1 was mounted | worn, (a) is AA sectional drawing of FIG. 2, (b) is sectional drawing in the case of only one unbonded PC steel twisted wire. is there. It is sectional drawing of the high frequency induction coil 10 of one embodiment of this invention. It is an experimental example which shows the relationship between an applied frequency, a high frequency current, and a fracture | rupture time. It is a schematic diagram of the high frequency induction heating anchor apparatus of the 2nd Example of this invention. It is a figure which shows the detail of the principal part of FIG. It is a circuit diagram which shows the connection of the coil in the case of two load-bearing bodies. It is a figure which shows the detail of the principal part provided with the coil protection tube.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Unbonded PC steel twisted wire 1a PC steel twisted wire 1b Synthetic resin sheath 2 Load-bearing body 2a Wedge 3 Mountain retaining wall 4 Fixing bracket 5 Anchor hole 6 Solidifying agent (groud)
DESCRIPTION OF SYMBOLS 10 High frequency induction coil, induction coil, coil 10a Coil copper wire 10b Insulation coating 10c Coil terminal 11 Lead wire 12 High frequency power supply device 13 AC power supply (commercial power supply)
21 first load bearing member 21a bearing plate 21b auxiliary bearing plate 21c friction rod 22 second load bearing member 22a bearing plate 22b auxiliary bearing plate 22c friction rod 23 first heating coil 24 second heating coil 25 crimping grip 26 crimping grip 27 tip Cap 28 Tip cap 29 Coil protective tube 29a Open window 31 PC steel stranded wire for first load bearing member 32 PC steel stranded wire for second load bearing member

Claims (3)

An unbonded PC steel stranded wire covered with a synthetic resin sheath is fixed to the distal end of the PC steel stranded wire with a crimping clip, and a load-bearing body connected thereto is embedded, and the load-bearing body is buried in a hole in the ground. A PC steel stranded wire removal device in construction work using a solidified material injected into a hole to form an anchor fixing portion, and the base end of the PC steel stranded wire is tensioned on the ground side,
The PC steel stranded wire is composed of a single strip or a plurality of strips, and the load bearing body reliably forms a fixed connection by injection of the solidified material to the respective strips, so that the strips or holes into which the respective strips are inserted, and
Each filament inserted and set in the filament groove or hole is wound in a cylindrical shape along the filament direction so that all the filaments for induction heating with a high frequency magnetic field are located on the inner peripheral side. High frequency induction coil,
A high-frequency current input / output terminal for applying a high-frequency current to the high-frequency induction coil from a high-frequency power supply device installed on the ground side through a twisted power supply line;
A high frequency resonance current having a resonance frequency f ₀ (1 / 2π (Ls · Cs) ^1/2 ) determined from an inductance Ls of the high frequency induction coil and a series capacitance Cs of an adjustment capacitor incorporated in the high frequency power supply device is induced. In a short time, the amount of heat flowing in the coil direction is reduced by maximizing the secondary induced current of the eddy current induced in the circumferential direction of each filament on the cylindrical inner circumference side of the coil. A high frequency induction heating anchor removing apparatus characterized by minimizing the breaking time of a strip. The secondary induced current induced in the circumferential direction of each filament due to the change of magnetic flux in the high frequency induction coil is utilized from the high frequency power supply device by utilizing the fact that the surface density of each filament is higher due to the skin effect. power to supplied to focus more than the surface side, high-frequency induction heating anchoring removing apparatus according to claim 1, wherein the operating at least 20KHz higher than the range of the resonance frequency f _0. A plurality of unbonded PC steel stranded wires covered with a synthetic resin sheath are provided, and the PC steel stranded wire ends are fixed to a crimping grip at the embedded steel wire end side, and a plurality of load-bearing bodies connected thereto are provided. Prepared,
These load-bearing bodies are embedded in a plurality of locations in the hole in the ground, and a fixing material is injected into the hole to form a plurality of anchor fixing portions, and the base ends of these PC steel stranded wires are tensioned on the ground side. A device for removing those PC steel stranded wires in construction work used as an earth anchor,
In order to reliably form a fixed connection by injecting the binding material to the PC steel stranded wires divided in advance for each load-bearing body, the load-bearing bodies have a plurality of filament grooves or holes inserted into the respective filaments. When,
Each of the plurality of load-bearing bodies is provided on the inner peripheral side of each of the filaments for induction heating with a high-frequency magnetic field. A high-frequency induction coil wound in a cylindrical shape along
All the input / output terminals of the high-frequency induction coil provided on the load-bearing body are all connected in series, and the high-frequency induction coil is connected to the high-frequency induction coil from a high-frequency power supply device installed on the ground side via a twisted power supply line. A high-frequency current input / output terminal for applying a high-frequency current,
Resonance frequency f ₀ (1 / 2π {(L ₁₎ determined from the inductances L ₁ , L ₂ ,... Of the plurality of high-frequency induction coils and the series capacitance Cs of the adjustment capacitors incorporated in the high-frequency power supply device. + L ₂ ...) Cs} ^1/2 ) is caused to flow through the induction coil, and is an eddy current 2 induced in the circumferential direction of each filament on the cylindrical inner peripheral side of the coil. A high frequency induction heating anchor removing apparatus characterized in that the next induced current is maximized and the breaking time of the filament is minimized within a short time when the amount of heat flowing in the wire diameter direction is small.

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