JP3628626B2 - Anchor cable - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an anticorrosion cable for anchors used for a long period of time for slope reinforcement, countermeasures for landslides, and the like and a construction method thereof.
[0002]
[Prior art]
As for the anticorrosion cable for anchors used for slope reinforcement, there are a wedge type and a sleeve type as techniques for fixing the cable after tension.
[0003]
(1) For the wedge type, as shown in FIG. 5, the PC steel strand 50 is fixed by the wedge 53 to the anchor disk 52 provided with the hole 51 through which the PC strand 50 is inserted, and the anchor plate 54 is used as a slope. This technology supports anchor disks and wedges.
[0004]
(2) For the sleeve type, as shown in FIG. 6, a PC steel wire is inserted into a steel sleeve 60 and crimped, and then the outer periphery of the sleeve 60 is threaded, and a nut 61 is attached to the threaded portion. It is a technology that is firmly established.
[0005]
These anticorrosion cables are accommodated in the boreholes, filled with grout in the boreholes and cured, and then tensioned and fixed with a predetermined tension. At that time, the anticorrosion cable is cut to a length obtained by adding the length required for the boring hole and the tension.
[0006]
Boring holes are excavated according to the length (design excavation length) determined in advance by investigation, but in actual construction, the drilling hole must be excavated to a length (actual excavation length) deeper than the design excavation length. There is a case.
[0007]
The wedge type anticorrosion PC steel strand is, for example, a resin coating on a bare PC steel strand. In this anticorrosion PC steel wire, as shown in FIG. 7, the long object 70 is wound in a coil shape and carried to the site, so that the length required for tension is added to the actual excavation length (actual cable). Appropriate construction is possible by cutting to a long length.
[0008]
The sleeve-type anticorrosion cable is, for example, a resin coated on a bare PC steel wire and further coated with polyethylene to form an unbonded cable. In this anticorrosion cable, a steel sleeve is attached to one end in advance at the factory by crimping, and the outer periphery of the sleeve is threaded. And the metal load-bearing body is attached to the other end of the unbonded PC steel strand, and it is in the state assembled as an anticorrosion cable system for anchors. In this case, the length of the cable is preliminarily adjusted and cut to a length (design cable length) obtained by adding a length necessary for tension to the design excavation length in advance at the factory.
[0009]
[Problems to be solved by the invention]
However, with the wedge type, it is necessary to set the wedge for each PC steel wire before inserting the PC steel wire into the hole of the anchor disk and fixing the tension at the construction site, which takes time and effort. In particular, when the design anchor force is large, there are many wires from the PC steel used, and it takes time and effort to set the wedge. Further, if the inner surface of the hole of the anchor disk is rusted, the wedge may not slide in when the tension is fixed, and the wire may slip from the PC steel.
[0010]
On the other hand, since the sleeve and the PC steel wire are integrated in the sleeve type, there is no problem of setting these wedges and slipping of the PC steel wire. However, with this technology, the length of the anchor cable is determined, so that if the actual cable length is different from the designed cable length, the construction cannot be performed. For example, as shown in FIG. 8, when the actual cable length is longer than the designed cable length, the sleeve 60 to be fixed enters the borehole 63 rather than the anchor plate 62, and the tensioning operation cannot be performed or the fixing is performed. You may not be able to.
[0011]
Accordingly, a main object of the present invention is to provide an anchor cable and an anchor cable construction method capable of adjusting the length of the anchor tip in accordance with the actual construction length in the field.
[0012]
[Means for Solving the Problems]
The present invention achieves the above object by making the fixing means a sleeve type and enabling the length of the anchor cable end to be adjusted.
[0013]
That is, the anchor cable of the present invention is a sleeve in which an anticorrosion PC steel wire in which a synthetic resin coating is provided on a bare PC steel wire, one end side of the anticorrosion PC steel wire is fixed inside, and a thread is formed on the outer periphery. The anticorrosion PC steel strand is characterized in that the other end side is not processed as a fixing length portion and is longer than the designed cable length.
[0014]
By making the fixing means into a sleeve type, it is possible to prevent troublesome construction that has been a problem with the wedge type and to prevent the wire from slipping from the PC steel. In addition, the anticorrosive PC steel wire is made longer than the designed cable length, and it is cut to the length corresponding to the actual cable length at the site by not processing the fixing length on the side opposite to the sleeve. It is possible to avoid the situation where the tension and fixing work cannot be performed.
[0015]
Hereinafter, the constituent requirements of the present invention will be described in more detail.
[0016]
As the anticorrosion PC steel strand, a bare PC steel strand coated with a synthetic resin is used. The synthetic resin is preferably an epoxy resin. This synthetic resin is preferably coated so that it not only covers the outer periphery of the stranded wire but also fills the gap between the strands, or covers each strand. Any cable coated with such a resin does not lose its anticorrosion performance even if its end is cut at the construction site.
[0017]
It is preferable to attach solid particles to the resin coating in order to increase the adhesion with the grout in the borehole. Specific examples of the solid particles include sand.
[0018]
The structure of the anticorrosion PC steel strand may be either an unbonded type or a non-unbonded type. For example, the following structure is mentioned.
[0019]
(1) Corrosion-proof PC steel strands having an unbonded structure in which the outer periphery of the synthetic resin coating on each PC steel strand is further covered with a sheath are used. The sheath at the end of the wire is removed from the anticorrosion PC steel and fixed in the sleeve.
[0020]
{Circle around (2)} A plurality of anticorrosion PC steel wires are bundled, and the unbonded anticorrosion PC steel wires having an outer periphery covered with a sheath are used. The sheath at the end of the wire is removed from the anticorrosion PC steel and fixed in the sleeve.
[0021]
(3) A plurality of anticorrosion PC steel wires that are not unbonded are fixed in the sleeve. The free length part covers the individual stranded PC steel wires with protective tubes at the construction site.
[0022]
(4) A plurality of anti-corrosion PC steel wires that are not unbonded are fixed in the sleeve. At the construction site, the free length part covers a plurality of anticorrosion PC steel wires together with a protective tube.
[0023]
As described above, the free length portion is protected by the sheath or the protective tube so that the synthetic resin coating of the stranded wire and the grout are not in contact with each other. The space between the sheath or protection tube and the anticorrosion PC steel wire may be either a gap or a cable that can be freely extended even if there is a filler such as grease.
[0024]
The sleeve attached to the tension side of the anticorrosion PC steel wire is a cylindrical body having a threaded outer periphery. This sleeve is usually made of steel. The PC steel strand is fixed in the sleeve by crimping the sleeve, or by inserting the PC steel strand into a hole having a predetermined diameter provided in the sleeve, and the hole and the PC steel strand. Filling the gap between the resin and solidifying the resin.
[0025]
The anticorrosion PC steel strand is made longer than the design cable length. The design cable length is a length obtained by adding a length necessary for tension to a design excavation length in advance at a factory. The design excavation length is the length of the drilling hole determined in advance by investigation. Usually, the design excavation length and the actual excavation length, which will be described later, have a deviation of about 1 to 2 m. Therefore, it is preferable that the anticorrosion PC steel strand is longer than the design cable length by about 2 m or more.
[0026]
The anchor cable construction method of the present invention is characterized by comprising the following steps.
(1) A process of cutting the above-mentioned anchor cable into a predetermined length at a construction site.
(2) A step of processing the cable as a fixing length portion.
(3) A process in which a cable subjected to this processing is inserted into a boring hole and is tensioned and fixed to form an anchor cable.
[0027]
In order to adjust the length after the anchor cable is carried into the actual construction site, the tip of the anchor cable is cut. Corrosion-proof PC steel wires are bare PC steel wires coated with resin, and even if the ends are cut, only the cut portions are subjected to anticorrosion processing, and the same anticorrosion cable as that manufactured at the factory is obtained. It is done.
[0028]
This cutting step is performed according to the actual cable length. The actual cable length is the length obtained by adding the length necessary for tension to the actual excavation length. The actual excavation length is the length of the boring hole to be actually excavated.
[0029]
The processing as the fixing length portion includes at least corrosion prevention processing of the cut end portion. This anticorrosion process is performed, for example, by applying a repair resin to the cut end. In the case of unbonded anticorrosion PC steel wire, the fixing length portion is processed by cutting the fixing length portion sheath, and in the case of non-unbonded anticorrosion PC steel wire, a protective tube is attached to the free length portion. Can be mentioned. In addition, mounting of load-resistant bodies, water-stopping processing at the boundary between the free length and fixing length, mounting of spacers that maintain the distance between individual anticorrosion PC steel strands, and binding of multiple anticorrosion PC steel strands are also established. Included in machining as long part.
[0030]
Either the anchor cable cutting step or the fixing length portion processing step may be performed first.
[0031]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below.
(Example 1)
First, an anchor cable using unbonded PC steel strand will be described.
The surface of the strand of bare PC steel with a diameter of 15.2 mm is washed with pickling or the like and then heated. Thereafter, the strands of the bare PC steel are unwound and an epoxy resin is applied by electrostatic powder coating, the twist is returned in the molten state, and then fine silica solid particles are adhered to the surface. In this way, when the powder is applied, the twist is first unwound and then returned to fill the triangular gap formed between the strands 1 with the resin 2 as shown in FIG. In addition, as shown in FIG. 1 (B), a resin coating 3 may be applied to each strand 1. Further, the solid particles 4 form a large number of fine irregularities on the surface of the resin coating, thereby improving the adhesion to the grout.
[0032]
Next, the wire is heated from the obtained PC steel to promote the curing of the epoxy resin, and an epoxy resin film having corrosion resistance is formed on the wire from the bare PC steel to a thickness of about 0.6 mm.
[0033]
Thereafter, a polyethylene sheath having an outer diameter of 23.5 mm and a wall thickness of 2 mm is formed on the outer periphery of the epoxy resin coating by extrusion to obtain a wire from unbonded anticorrosion PC steel.
[0034]
Here, since the design cable length obtained based on the design excavation length was 21 m, a 23 m long anticorrosion PC steel wire longer than the design cable length is prepared. Four strands of this anticorrosion PC steel are bundled in the factory, and a sleeve is attached to the end. As shown in FIG. 2, the sleeve 10 is a steel cylindrical body having an inner diameter of 46.7 mm, an outer diameter of 80 mm, and a length of 60 cm, and is threaded on the outer periphery. The polyethylene sheath 5 is previously peeled off at a portion of the anticorrosion PC steel wire to be inserted into the sleeve 10. The gap between the sleeve 10 and the epoxy resin-coated PC steel wire 6 is filled with the epoxy resin 11 and hardened, and the anticorrosion PC steel wire is fixed in the sleeve 10. At this time, the polyethylene sheath 5 having a free length is not allowed to enter the sleeve 10.
[0035]
The anchor cable processed in the factory as described above is transported to the construction site. Although the designed cable length was 21 m, the actual cable length was 22 m. Therefore, as shown in FIG. 3A, the tip of the anchor cable 20 is cut only by a length of 1 m out of the total length 23 m. Then, a repairing epoxy resin is applied to the cut end.
[0036]
Thereafter, as shown in FIGS. 3B and 3C, the polyethylene sheath 5 of the fixing length corresponding to the length to be attached to the grout is cut and peeled over a length of 5 m. Then, the boundary portion between the portion where the polyethylene sheath 5 is present and the portion where the polyethylene sheath 5 is not present is subjected to a water stop treatment with the heat shrinkable polyethylene tube 21. The heat-shrinkable polyethylene tube 21 has an inner surface to which a resin that melts by heat is attached, and can improve sealing performance.
[0037]
Next, spacers 22 are arranged at 1 m intervals in the fixing length portion. The spacer 22 is a spherical body having a plurality of grooves, and the anchor cables 20 of the fixing length portions fitted in the grooves are arranged uniformly on a concentric circle. Moreover, the both sides of the spacer 22 bind each epoxy resin-coated PC steel wire 6 with a binding band 23 made of synthetic resin (for example, vinyl). Further, a tip cap 24 is attached to the tip of the fixing length portion (FIG. 3D).
[0038]
Thereafter, as shown in FIG. 2, in order to perform a water-stop treatment behind the sleeve, a foot-shaped heat-shrinkable polyethylene tube 12 having a hole with an inner diameter corresponding to the outer diameter of the individual epoxy resin-coated PC steel is provided. Cover. The heat-shrinkable polyethylene tube 12 also has an inner surface to which a resin that melts by heat is attached, so that the sealing performance can be improved.
[0039]
The cable subjected to the above processing is inserted into a predetermined boring hole. Then, the tension | tensile_strength side cable edge part is arrange | positioned in the position where tension | tensile_strength fixation is possible.
[0040]
Further, as shown in FIG. 2, the sheath 13 with the collar is wrapped with the heat-shrinkable polyethylene tube 12 behind the sleeve and placed on the anchor plate 14. Thereafter, the grout is filled between the boring hole and the anchor cable and cured to a predetermined strength. Then, the sleeve side of the cable is tensioned to a predetermined strength, and the state is maintained, and the nut 15 is tightened and fixed to the screw portion on the outer periphery of the sleeve.
[0041]
In the above description, the wire is made of an individual anticorrosion PC steel strand, but it may be an unbonded structure in which a plurality of wires of the anticorrosion PC steel are collectively covered with a sheath.
[0042]
(Example 2)
Next, an anchor structure in which a free length portion is formed by covering a plurality of anticorrosion PC steel wires together with a protective tube will be described.
[0043]
In this case as well, the same applies as in Example 1 except that a corrosion-resistant PC steel wire having an epoxy resin coating formed on the bare PC steel wire is used, and a sleeve is attached to the end of the wire.
[0044]
In this example, since the wire is not an unbonded type from the anticorrosion PC steel, the free length portion is formed by attaching a protective tube at the construction site. As shown in FIG. 4 (A), four anticorrosion PC steel wires 30 in which an epoxy resin coating is formed on a bare PC steel wire with a diameter of 15.2 mm in the same manner as in Example 1 are prepared, and these are grout-injected. Bundle with pipe 40. Although not shown in FIG. 4, a sleeve similar to that of the first embodiment is attached to the tension side end (left side in FIG. 4). In the factory, processing is performed until the end of the wire 30 is fitted with a sleeve from the anticorrosive PC steel, and in that state, the processing is carried to the construction site to perform processing as a fixing length portion and a free length portion.
[0045]
First, the end portion of the wire 30 is cut from the anticorrosion PC steel according to the actual cable length, and a repair epoxy resin is applied to the cut end portion.
[0046]
Spacers 31 and 32 are attached to each of the free length portion and the fixing length portion, and the wires of the anticorrosion PC steel are held in a predetermined arrangement. Here, the spacers 31 are mounted at intervals of 5 m in the free length portion, and the spacers 32 are mounted at intervals of 1.5 m in the fixing length portion. The spacers 31 and 32 are spherical bodies having an insertion hole for the grout injection pipe 40 at the center and a groove into which the wire 30 is inserted from each anticorrosion PC steel on the outer periphery. Both sides of the spacers 31 and 32 were bound by a binding band 33.
[0047]
Next, a polyethylene protective tube 34 covering the four anticorrosion PC steel strands 30 and the injection pipe 40 is fitted into the free length portion. As shown in FIG. 4B, four anticorrosion PC steel wires 30 are arranged on the outer periphery of the grout injection pipe 40, and the outer periphery is collectively covered with a protective tube 34. And like Example 1, while attaching the front-end | tip cap 35 to the front-end | tip part of the anticorrosion PC steel strand 30, forming the water stop part 36 in the boundary part of a free length part and a fixing length part, To do.
[0048]
After performing the above processing, the anchor cable is housed in the boring hole, and the grouting process and the tension / fixing of the anchor cable are the same as in the first embodiment.
[0049]
Even in the case of this example, the cable can be cut to a length corresponding to the actual cable length at the site, and the tension / fixing operation can be performed reliably. In addition, fixing work can be easily performed by using a sleeve type fixing means.
[0050]
In the above description, a plurality of anticorrosion PC steel strands are collectively covered with a protective tube, but each anticorrosion PC steel strand may be covered with a protective tube.
[0051]
【The invention's effect】
As described above, according to the anchor cable of the present invention, the fixing means is a sleeve type, thereby preventing troublesome construction that has become a problem with the wedge type and preventing the wire from slipping from the PC steel. be able to.
[0052]
In addition, the anticorrosive PC steel wire is made longer than the designed cable length, and it is cut to the length corresponding to the actual cable length at the site by not processing the fixing length on the side opposite to the sleeve. It is possible to avoid the situation where the tension and fixing work cannot be performed.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a coated PC steel strand used for an anchor cable of the present invention, in which (A) is a cable in which resin is filled in a gap between strands, and (B) is resin-coated for each strand. Show cable.
FIG. 2 is a longitudinal sectional view showing a state in which a corrosion prevention PC steel stranded wire and a sleeve are mounted.
FIGS. 3A and 3B are explanatory diagrams of work at the construction site of the cable of the present invention, in which FIG. 3A is before cutting the wire from the anticorrosion PC steel, FIG. 3B is after cutting the wire from the anticorrosion PC steel, and FIG. , (D) shows a state after processing of the fixing length portion.
4A is a schematic view of a cable of the present invention in which a plurality of anticorrosion PC steel strands are collectively stored in a protective tube, and FIG. 4B is a cross-sectional view taken along the line AA in FIG.
FIG. 5 is a schematic diagram showing a wedge-type fixing structure.
FIG. 6 is a schematic view showing a sleeve type fixing structure.
FIG. 7 is a schematic view showing a form when a wedge-type anticorrosion PC steel strand is carried into a construction site.
FIG. 8 is an explanatory view showing a state in which a sleeve-type sleeve is not exposed to the outside of the boring hole.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Strand 2 Resin 3 Resin coating 4 Solid particle 5 Polyethylene sheath 6 Epoxy resin coating PC steel strand 10 Sleeve 11 Epoxy resin 12 Heat shrinkable polyethylene tube 13 Sheath 14 Anchor plate 15 Nut 20 Anchor cable 21 Heat shrinkable polyethylene tube 22 Spacer 23 Cable tie 24 Tip cap 30 Anticorrosion PC steel strand 31 Spacer 33 Cable tie 34 Protective pipe 35 Protective tube 35 Tip cap 36 Water stop 40 Graut injection pipe 50 PC steel strand 51 Hole 52 Anchor disk 53 Wedge 54 Anchor plate 60 Sleeve 61 Nut 62 Anchor plate 63 Boring hole 70 Long object

Claims (4)

Corrosion-proof PC steel wire with synthetic resin coating on bare PC steel wire, and one end side of the anti-corrosion PC steel wire is fixed inside, and has a sleeve that is threaded on the outer periphery,
The anti-corrosion PC steel strand is not processed as a fixing length on the other end side, and is longer than the designed cable length, so that the other end side can be cut to a length corresponding to the actual cable length. An anchor cable characterized by being constructed. The anticorrosion PC steel strand is an unbonded structure in which the outer periphery of the synthetic resin coating is further covered with a sheath, and the anticorrosion PC steel strand is fixed in the sleeve by removing the sheath at the end. The anchor cable according to claim 1. The anti-corrosion PC steel strand has an unbonded structure in which a plurality of bundles are bundled and the outer periphery of the bundle is further covered with a sheath. The anchor cable according to claim 1, wherein the anchor cable is provided. A step of cutting the anchor cable according to any one of claims 1 to 3 to a predetermined length at a construction site, a step of processing the cable as a fixing length portion, and a cable subjected to the processing in a borehole An anchor cable construction method comprising a step of inserting and tensioning and fixing.

Images