JPH07145618A - Earth anchorage method - Google Patents

Abstract

PURPOSE:To easily form the respective parts of the free length and the anchorage length of a tension rod inserted in an anchor hole in an earth anchorage method, and obtain a sufficient adhesion with the solidified material in the anchorage part by keeping the sliding motion and the anti-corrosion of the free part. CONSTITUTION:A synthetic resin coated intermediate cylinder and a synthetic resin coated external cylinder are provided on a prestressing steel strand 20a by a synthetic resin extruding means and a lubricant is interposed therebetween. The synthetic resin coated intermediate cylinder, the synthetic resin coated external cylinder, and the lubricant of the front part 27 of the tension rod 20 on which a synthetic resin powder-molten coated inner layer is formed on respective outer periphery of the core line and the side line, are peeled off to make the anchorage the ground 1 and a solidifying agent 4 is charged by a specified volume and a specified tensile strength is added to the rear end of tension rod protruding outward by a tension means 28 and anchor it with tension by an anchorage material 29.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ground anchor construction method for supporting earth retaining walls, preventing fall of retaining walls and bridge piers, and preventing slippage of slopes in root cutting work.

[0002]

2. Description of the Related Art Conventionally, in order to make a permanent anchor by using a PC stranded wire, as shown in FIG. 6, a hole 1 for an anchor is drilled in a ground 1 on which a retaining wall is to be constructed. The distal end portion of the tension material 3 made of PC steel wire is inserted into the hole 2 so as to have a predetermined gap with the peripheral wall surface of the hole 2.

Then, the space of the hole 2 is filled with a solidifying material 4 such as mortar or concrete, and after the solidifying material 4 solidifies to exhibit the required strength, the rear end of the tensioning material 3 is tensioned. The retaining wall is firmly held by pulling it with a tensioning means (not shown) such as a jack to apply a predetermined tensioning force.

In this case, the free end portion 5 having a resin coating layer for protecting the PC stranded wire at the tip of the tension member 3 to be inserted into the hole 2 and the PC by peeling off the resin coating layer. It is processed into a fixing length portion 6 where the steel strand is exposed to the outside.

The free length portion 5 is an elastic body that can be slid freely in the axial direction of the tension member 3 with less friction resistance against the solidified material 4 even after the solidified material 4 has been cast and solidified.
On the other hand, the fixing long portion 6 is in complete contact with the solidifying material 4 and has a large adhesive force to be a load bearing body.

Then, in order to make the tip portion of the tension member 3 the fixing length portion 6, the resin coating layer of the outer cylinder is peeled off to expose the PC steel wire to the outside, so that rust may occur. There was a problem that the adhesive force with the solidifying material 4 was reduced.

As a rust preventive method against this, conventionally, as shown in FIG. 7, there is a grease-like consistency with respect to permeability during operation, and around the twisted cord 7, at least 2 mils more than the diameter of the twisted cord. A seamless plastic jacket consisting of ropes 7,7a of multi-stranded single wire covered with a corrosion inhibitor 8 in an amount sufficient to provide a large diameter annular covering, and tightly covering said covered rope 7. Tensile material 10 having 9 (Japanese Patent Publication No. 53-47609)
Was used.

As another tension material, as shown in FIG. 8, when an extruder resin coating layer is provided on the PC steel strand 11, it is at least 50% higher than the melting temperature of the resin pellets.
Primary resin coating layer 12 by heating the wire from PC steel above ℃
Is provided, and then the surface of the secondary resin coating layer 1 formed by an extruder method or the like is further provided on the surface thereof by thinly applying an oil-based material on the surface thereof to provide an oil-and-fat coating layer 13 or without coating.
4 was used (Japanese Patent Publication No. 2-60504).

[0009]

However, since the above-mentioned tension material 10 is the one in which the grease-like corrosion inhibitor 8 is applied more around the rope 7, the fixing long portion 6 serving as a load bearing body.
Even if the plastic jacket 9 is peeled off, the corrosion inhibitor 8 cannot be completely removed, and the adhesion or adhesive force of the fixing length portion 6 with the solidifying material 4 is significantly reduced.
There is a problem that it cannot be used for the fixed length portion.

In the tension member 10, the plastic jacket 9 is coated so as not to apply the corrosion inhibitor 8 in advance in the range of the tip portion which becomes the fixing length portion 6, and the coating layer of the corresponding portion is coated. Stripped and fixed length 6
However, in this case, if the lengths of the free length portion 5 and the fixing length portion 6 are not determined, not only the covering process cannot be performed but also the dimensions of the fixing portion 6 and the like are changed. There is a problem that it cannot be used even with the above coating process.

In the tension member 15, the purpose is to fuse the primary resin coating layer 12 to the PC steel wire 11 to enhance the rust preventive effect. The primary resin coating layer 12 is provided by heating the PC steel wire 11 at a temperature of at least 50 ° C. or higher. Therefore, there is a problem that it is not easy to cleanly peel off the primary coating layer 12 from the surface of the PC steel wire 11 in order to form the fixed length portion 6 serving as a load bearing body.

The present invention has been made in view of the above problems, and facilitates the formation of a free length portion and a fixing length portion of a tension member that is inserted into a hole for an anchor as a ground anchor. An object of the present invention is to provide a ground anchor construction method capable of maintaining the sliding and rustproofing power of the long portion and sufficiently obtaining the adhesive force of the fixing long portion to the solidifying material.

[0013]

Means for Solving the Problems The object of the present invention to solve the above problems and achieve the above objects is to synthesize a PC steel strand in which a plurality of side wires are twisted around a core wire by a synthetic resin extrusion molding means. A resin-coated middle-layer cylinder and a synthetic-resin-coated outer-layer cylinder are provided, and a lubricant is interposed between the synthetic-resin-coated middle cylinder and the synthetic-resin-coated outer-layer cylinder, and a synthetic resin powder paint is applied to each outer periphery of the core wire and the side wire. The tip portion of the tension material, which is melt-adhered to form the synthetic resin powder melt-coated inner layer, is separated from the synthetic resin-coated middle layer cylinder, the synthetic resin-coated outer layer cylinder and the lubricant to form a fixing long portion, and the tip portion is ground. Of the tensioning material, which is inserted into the anchor hole, is then filled with a predetermined amount of the solidifying material into the hole, and after the solidifying material is solidified, the rear end portion of the tensioning material protruding from the opening of the hole to the outside is tightened. To add a predetermined tension and tighten the fixing material. Is obtained by the fixing is not a method. Further, in order to easily form the fixed length portion, the synthetic resin-coated middle layer cylinder and the synthetic resin powder melt-coated inner layer are formed of synthetic resins having different properties and not welded to each other.

[0014]

According to the earth anchor construction method of the present invention, since the synthetic resin melt coating inner layer substantially completely prevents rust in the fixing length portion of the tension member, rust does not occur on the PC steel wire and the concrete The adhesive strength with the solidified material such as the above-mentioned material also exhibits a strength higher than the adhesive strength in the case of a bare PC steel wire. Further, when the fixed length portion is formed, the synthetic resin-coated middle layer cylinder is made of a material which is easily welded to the inner layer of the synthetic resin powder melt coating and easily peeled off, thereby facilitating the peeling work of the tip portion. Furthermore, the lubricant does not adhere to the fixing length portion, the adhesive force with the solidifying material is maintained, and the sliding of the free length portion in the axial direction is also maintained.

[0015]

Embodiments of the present invention will now be described in detail with reference to FIGS. FIG. 1 is a vertical sectional view of an embodiment of a ground anchor method according to the present invention. In addition,
The parts corresponding to the conventional example will be described with the same reference numerals for easy understanding.

The earth anchor construction method of the present invention comprises a core wire 21.
A synthetic resin-coated middle-layer cylinder 23 and a synthetic-resin-coated outer-layer cylinder 24 are provided by a synthetic-resin extrusion molding means on a PC steel stranded wire in which a plurality of side wires 22 are twisted around the periphery of the The sliding member 25 is interposed between the outer layer cylinder 24 and the synthetic resin powder coating material is melt-adhered to the outer circumferences of the core wire 21 and the side wire 22 to form the synthetic resin powder melt-coated inner layer 26. Part
The synthetic resin-coated middle layer cylinder 23 and the synthetic resin-coated outer layer cylinder 24
Then, the lubricant 25 is peeled off to form a fixed length portion 27, the tip portion is inserted into the anchor hole 2 of the ground 1, and then the hole 2 is filled with a predetermined amount of the solidifying material 4, and the solidifying material is formed. After the solidification of No. 4, the tension member 20 protruding from the opening of the hole 2 to the outside
This is a construction method in which a predetermined tension force is applied to the rear end portion by a tensioning means 28 and the fixing material 29 is tensioned and fixed.

The tension member 20 is formed by the processing steps shown in FIG. That is, the apparatus in this processing step performs a preparatory work prior to continuous operation. First, the tip of the PC steel wire 20a is pulled out from the rewinding device 31, and is sandwiched between the endless belts 33a and 33b of the feeding device 33,
It is sent to the loosening device 36 through the deposit removing device 34 and the heating device 35.

In the loosening device 36, the PC steel strand 2
0a is manually untwisted over a fixed length to form a loosened portion of each side wire 22 by a fixed length, and the tip side is manually twisted again. This re-twisting does not require much labor because each side wire 22 is permanently deformed to a more state. Then, a leading wire (not shown) is fixed to the twisted tip portion.

The lead wire is led through the powder coating material supply device 45, the post-heating device 48, the cooling device 49, the extrusion molding machine 55, the cooling device 56, the lubricant coating device 57, the extrusion molding machine 58, the cooling device 59 and the drawing device 50. The wire is wound around the wire winding device 53.

When each device is driven in this state to start continuous operation, the PC steel strand 20a is continuously drawn out from the rewinding device 31 to the feeding device 33, and passes through each device to obtain a predetermined synthetic resin. The coating forming process is performed, and the drawing device 50 sequentially draws.

Then, when the portion that has been subjected to the synthetic resin coating forming processing is pulled out of the pulling device 50, the incomplete portion on the tip side is cut off, and is sequentially pulled out completely. The tension member 20 coated with the resin is wound on the wooden drum 52 of the winding device 51.

Among the synthetic resin coating forming methods, the coating layer forming treatment step up to the inside (side wire / core wire) of the PC steel strand 20a and the coating layer formation of the fixed length portion will be described. The PC steel stranded wire 20a is adapted to prevent rotation in the circumferential direction while applying a constant tension by proportional control between the feeding device 33 and the drawing device 50, and to move only in the axial direction.

In the heating device 35, the relaxation device 36 in the next step is used.
In, the twisting of the PC steel wire 20a is loosened, but the PC steel wire 20a immediately before the softening is heated to a temperature at which plastic working strain does not occur due to the loosening, for example, about 300 to 350 ° C. Then, the PC steel strand 20a is sent to the loosening device 36 while being heated.

In the loosening device 36, the PC steel stranded wire 2
In accordance with the twisting pitch of 0a, the loosening guide plate is rotated by the driving device in the twisting direction, whereby the PC
The steel stranded wire 20a is always maintained in the unraveled state by the fixed length unraveled in the previous preparation work, and is automatically retwisted after moving beyond the fixed length.

The unfixed length is such that the synthetic resin powder coating material, which will be described later, is sprayed, and the hardening starts after the material is melted and adhered by the heating temperature for preventing the plastic deformation strain due to the loosening, and the fixed time for the hardening. The length is set in advance to maintain the loosened state.

The heating performed by the heating device 35 is for loosening the PC steel stranded wire 20a in a warm state at a predetermined temperature, which is different from the conventional cold loosening.
There is no processing strain on the lateral line 22 and the bluing effect is maintained, so when twisting is returned again,
Each lateral line 22 is completely restored to its original state. At the same time, the heating also serves to melt and adhere the subsequent synthetic resin powder paint to the entire circumferences of the side wire 22 and the core wire 21 to form the synthetic resin powder melt coating inner layer 26.

PC steel stranded wire 2 loosened in the above-mentioned state
0a enters the spray booth of the powder coating supply device 45, and the synthetic resin powder coating charged with a negative charge is sprayed by the spray gun.
6 adheres to the surface of each side wire 22 and core wire 21 to which a positive charge is applied and melts and adheres to each other, and a synthetic resin powder melt coating inner layer 26 having a substantially uniform thickness is formed on the outer periphery of each side wire 22 and core wire 21. It is formed.

Thus, the synthetic resin powder melt coating inner layer 26
Is formed, passes through a certain length, and is twisted again, so that each side wire 22 is twisted around the core wire 21 around the core wire 21, and the rustproof PC steel twisted wire 20b is formed. Becomes Then, the surface of the synthetic resin powder melt-coated inner layer 26 is reheated by the post-heating device 48, and the surface of the synthetic resin powder melt-coated inner layer 26 is cooled by the subsequent cooling device 49 so that the synthetic resin powder melt-coated inner layer 26 melted and adhered completely. Hardened.

As described above, the so-called rustproof PC steel stranded wire 20b in which the synthetic resin powder molten coating inner layer 26 is formed on the entire surface of each side wire 22 and the core wire 21, the free length portion 30 and the fixing length portion 27. In order to make it possible to simply provide the synthetic resin powder, the extruder 55 forms a synthetic resin coated middle layer cylinder 23 having a different property that does not weld to the synthetic resin powder molten coating inner layer 26, and passed through the cooling device 56. After that, the lubricant 25 for reducing the frictional resistance of the free length portion 30 is applied to the surface of the synthetic resin-coated middle-layer cylinder 23 by the lubricant applying device 57.

Subsequently, the coated surface of the lubricant 25 is fitted and covered by the extrusion molding machine 58 of the next stage, cooled to room temperature by the cooling device 59, and continuously drawn by the drawing device 50. And is sequentially taken up by the winding device 51. The tendon 20 processed in this way has a cross-sectional configuration as shown in FIG.

In order to use the tension member 20 thus coated with the synthetic resin as a ground anchor,
Further, a peeling process is performed to form the fixing long portion 27 at the tip portion thereof so as to be a load bearing body.

In this peeling process, the tension member 20 is cut into a predetermined length, and the free length portion 30 serving as an elastic body and the fixing length portion 27 serving as a load bearing body are dimensionally indexed, as shown in FIG. In addition, the fixing length portion 27 is a synthetic resin-coated outer layer cylinder 24,
The lubricant 25 and the synthetic resin coated middle layer 23 are peeled off.

In this peeling operation, the lubricant 25 is interposed between the synthetic resin-coated outer layer cylinder 24 and the synthetic resin-coated middle layer cylinder 23 and is removed as it is, so that the lubricant 25 is peeled off. The subsequent adhesion to the surface of the synthetic resin powder melt coating inner layer 26 is prevented. Further, since the synthetic resin-coated middle layer cylinder 23 is formed of a different material that is not welded to each other and is easily peeled off from the synthetic resin powder melt-coated inner layer 26, the peeling work can be performed very easily.

In this way, the tension material 20 having a predetermined length and the fixing length portion 27 formed at the tip portion thereof is inserted into the anchor hole 2 of the target ground 1 from the tip portion, and the solidifying material 4 such as concrete is fixed. After fixing the fixing material, the rear end portion of the tension member 20 projecting from the opening of the hole 2 after being filled by casting and solidifying the binding material 4 is applied with a predetermined tension force by a tension means 28 such as a jack. Tension is fixed at 29.

As described above, according to the earth anchoring method of the present invention, since the fixed length portion 27 of the tension member 20 is substantially completely rust-proofed by the synthetic resin molten coating inner layer 26, the PC steel stranded wire 20a is formed. No rust is generated, and the adhesive strength with a solidifying material such as concrete is greater than the adhesive strength of a bare PC stranded wire.

Further, when the fixing length portion 27 is formed, the synthetic resin-coated middle layer cylinder 23 has the synthetic resin powder melt-coated inner layer 26.
By using a material that can be easily peeled off without welding, the work of peeling off the tip portion is facilitated, and the lubricant 25
Does not adhere to the synthetic resin powder melt coating inner layer 26, and
The adhesive force with does not decrease.

[0037]

As described above, according to the ground anchor construction method of the present invention, a PC steel stranded wire in which a plurality of side wires are twisted around a core wire is covered by a synthetic resin extrusion molding means by a synthetic resin coating middle layer cylinder and a synthetic resin coating. An outer layer cylinder is provided, and a lubricant is interposed between the synthetic resin-coated middle cylinder and the synthetic resin-coated outer cylinder, and synthetic resin powder paint is melt-adhered to the outer circumferences of the core wire and side wires to melt the synthetic resin powder. The tip portion of the tension material having the inner coating layer formed thereon is peeled off from the synthetic resin-coated middle layer cylinder, the synthetic resin-coated outer layer cylinder and the lubricant to form a fixing long portion, and the tip portion is inserted into the anchor hole of the ground. After that, a predetermined amount of a solidifying material is filled in the hole, and after the solidifying material is solidified, a predetermined tension force is applied to the rear end portion of the tension material protruding outside from the opening of the hole by a tensioning means. The tension was fixed with a fixing material. Further, the synthetic resin coated middle barrel synthetic resin powder melted coating the inner layer, so using a tendon formed by synthetic resin which does not welded to each other different in nature,
In the fixed length portion, the synthetic resin melt coating inner layer is almost completely rust-proofed, so that rust does not occur on the PC steel wire and the quality is improved, and the adhesive strength to the solidifying material such as concrete is also naked. It has an excellent effect that it exerts strength more than the adhesive force in the case of the PC steel stranded wire, and when forming the fixing length portion, the synthetic resin coated middle layer cylinder is welded to the synthetic resin powder melt coated inner layer. By using a material that can be easily peeled off without doing so, it is possible to achieve an excellent effect that the work of peeling off the tip portion becomes easy and the construction period and cost are reduced.

Further, since the lubricant is interposed between the synthetic resin-coated outer layer cylinder and the intermediate layer cylinder and removed as it is during the peeling work, the lubricant is not adhered to the fixing length portion and is solidified. It has an excellent effect that the adhesive force of the above is maintained and the sliding of the free length portion in the axial direction is also maintained.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view illustrating an implementation state of a ground anchor method according to the present invention.

FIG. 2 is a block diagram for explaining a manufacturing process of a tension member used in the earth anchor method.

FIG. 3 is a vertical cross-sectional view of the tension member taken along the line AA in FIG.

FIG. 4 is a side view showing a free length portion and a fixed length portion of the tension member.

5 is a vertical sectional view taken along the line BB of FIG.

FIG. 6 is a vertical cross-sectional view illustrating a ground anchor method according to a conventional example.

FIG. 7 is a vertical sectional view of the tension member.

FIG. 8 is a vertical sectional view of another tension member.

[Explanation of symbols]

 1 ground, 2 holes, 4 consolidation material, 20 tension material, 20a PC stranded wire, 20b rustproof treated PC steel stranded wire, 21 core wire, 22 side wire, 23 synthetic resin-coated middle-layer tube, 24 synthetic resin-coated outer layer tube, 25 lubricant, 26 synthetic resin powder melt coating inner layer, 27 fixing length part, 28 tension means, 29 fixing body, 30 free length part.

Claims (2)

[Claims] 1. A synthetic resin-coated middle-layer cylinder and a synthetic-resin-coated outer-layer cylinder are provided by a synthetic resin extrusion molding means on a PC steel stranded wire in which a plurality of side wires are twisted around a core wire, and the synthetic resin-coated middle cylinder is synthesized. While interposing a lubricating material between the resin-coated outer layer cylinder, the tip end portion of the tension material, in which the synthetic resin powder coating material is melt-adhered to the outer periphery of each of the core wire and the side wire to form a synthetic resin powder molten coating inner layer, The synthetic resin-coated middle layer cylinder and the synthetic resin-coated outer layer cylinder and the lubricant are peeled off to form a fixing length portion, the tip portion is inserted into a hole for anchor of the ground, and then the hole is filled with a predetermined amount of a solidifying material, A ground anchor characterized in that after the solidifying material is solidified, a rear end portion of the tension material protruding from the opening portion of the hole is applied with a predetermined tension force by a tensioning means to be tension-fixed by a fixing material. Construction method. 2. The earth anchor construction method according to claim 1, wherein the synthetic resin-coated middle layer cylinder and the synthetic resin powder melt-coated inner layer are tension members made of synthetic resin having different properties and not welded to each other.