JP2557036B2 - Unbonding method for anchor cable - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ground anchor cable which is buried in the ground to fix a structure or the like, and particularly to allow free extension of the anchor cable when prestressing force is applied. The present invention relates to a method of processing into unbonded.

[0002]

2. Description of the Related Art In a ground anchor for burying a structure or the like on the ground by burying it in the ground, a plurality of PC steel stranded wires are used as anchor cables, which are inserted into a drilled hole in the ground. A hardening material such as cement milk is injected into the drilled hole, and the tip of the PC steel wire, that is, the portion located at the back of the drilled hole is used as a fixing long portion to which the hardening material is attached and fixed. The portion on the ground side from this is an unbonded portion, that is, a portion that does not adhere to the hardening material, and is a free length portion in which the cable freely extends when a prestressing force is applied to the cable. In the case of unbonding the free length portion, as shown in FIG. 9, it was general to pass each strand a of PC steel through a separate unbonded sheath b such as polyethylene.

However, passing each of the PC steel strands a through a separate unbonded sheath is cumbersome and expensive, and requires a long delivery time. Further, the thickness of the sheath b is as thin as about 1.0 to 1.2 mm, and it is necessary to pass the portion passed through the unbonded sheath b into the thicker free-length sheath c in order to protect the cable. A plurality of PC steel wires a passed through the unbonded sheath b are put together and passed through the free length sheath c.
The thickness of the unbonded sheath b of the steel stranded wire a occupies a considerable space as a whole, and the free length sheath c
The diameter of was very large. This free length sheath c
The diameter of the hole to be inserted must be increased by that much, and even if the diameter of the hole is increased by 10 mm, the construction becomes large, which is a cause of high construction cost.

[0004]

For this purpose, as shown in FIGS. 7 and 8, the free length portions of a plurality of PC steel stranded wires a are put together so that the wall thickness is about 3.5 to 8 mm. It is also adopted that the diameter of the anchor is reduced by passing it through the unbonded sheath d of the book. A rust preventive oil f is filled in a gap between the PC steel strands of the unbonded sheath d to prevent water from entering. In order to fill the unbonded sheath d with this rustproof oil f, the rustproof oil f warmed and fluidized was poured from the end of the sheath d using a funnel or the like.

However, the free length is several tens of meters, and the warmed anticorrosion oil f touches the sheath d and the PC steel wire a to cool and harden on the way, and it is not possible to completely fill the entire length of the sheath d. It was possible. For this reason, a hole was made in the middle of the unbonded sheath d, and rust-preventing oil was poured again from here, but it is not preferable to make a hole in the sheath d because water or the like may enter. . For this purpose, as shown in FIG. 10, the unbonded sheath d is dipped in the rust preventive oil f contained in the long box-shaped oil tank e while the unbonded sheath d is stretched, and the oil f is immersed in the unbonded sheath d. There is also a method, but unbonded sheath d
However, the air in the sheath d was not sufficiently escaped by just lying in the oil f, and it was difficult to fill the oil f. Further, the oil tank e takes a flat place, and warms the oil f in order to fluidize it so that it can easily enter the sheath, but it is difficult to heat because the oil tank e is large.
It was also necessary to remove the anticorrosion oil that had adhered to the sheath.

The present invention has been made to solve the above problems, and is an unbonding method for an anchor cable that can be unbonded by filling the entire length of the free length sheath with rust preventive oil without any voids. The purpose is to provide.

[0007]

According to the method for unbonding an anchor cable of the present invention, a part of a plurality of PC steel wires is used as a free length portion, and the PC steel wires are aligned so that the free length portion is equalized. Thread through the unbonded sheath of the book. As the unbonded sheath, a synthetic resin sheath having a wall thickness of about 3.5 to 8 mm is adopted. The unbonded sheath through which the plurality of PC steel strands pass is formed into a curved shape, and all or part of this unbonded sheath is immersed in a hot water tank. The term “curved” means a form including various curves for shortening a long sheath, such as spirally winding and folding back with a curve. There is hot water in the hot water tank. As means for warming the water, heating may be performed from below the hot water tank, or a heater may be placed in the hot water tank to heat the water. It is also possible to position one end of the unbonded sheath high and inject the rust preventive oil as if pouring into the unbonded sheath. After the oil is filled, pull up with both ends of the unbonded sheath positioned above. Specifically, it is lifted from warm water by lifting it with a rope. Allows the antirust oil in the unbonded sheath to cool and harden.

Instead of the hot water tank, a part or all of the unbonded sheath may be placed in a high temperature tank filled with high temperature air and rust preventive oil may be injected. Further, in the above method, the pouring port may be injected into the unbonded sheath in a state of being pressurized at a low pressure instead of or at a high position.

[0009]

Function: The unbonded sheath is immersed in a deep water tank or put in a high temperature tank, so that the oil in the sheath flows well, and the oil easily fills the sheath.
Since the sheath is rolled up and placed in a deep hot water tank, the space occupied by the hot water tank and high temperature tank can be small. It is easy to heat hot water or air.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below based on the embodiments shown in the drawings. In the figure, reference numeral 1 denotes an unbonded sheath made of synthetic resin, and a plurality of steel strands 2 serving as anchor cables are aligned and inserted into the unbonded sheath 1. A part of the PC steel stranded wire 2 is exposed from the unbonded sheath 1 to form a fixing long portion 3. The unbonded sheath 1 is wound up in a spiral shape. It is not always necessary to wind up the fixing long portion 3 that has been exposed.

In the figure, reference numeral 4 is a hot water tank, which has a bathtub-like shape with a deeper depth, and is heated by a heater 5 from below the hot water tank 4. The unbonded sheath 1 is immersed in the hot water tank 4. In the embodiment, both ends of the unbonded sheath 1 wound by the rope 7 are suspended and immersed in the warm water 6. One end of the unbonded sheath 1 is located on the bottom side of the hot water tank 4, the fixing long part 3 side at the other end is located near the surface layer of the warm water 6, and the fixing long part 3 is not immersed in the warm water 6. A spout attachment 8 that functions as a funnel is attached to one end of the unbonded sheath 1, the attachment 8 is positioned higher than the other portions of the unbonded sheath 1, and a rust preventive oil 9 that is heated and fluidized from there is applied. inject. Since the attachment 8 side is located high, the entire length of the unbonded sheath 1 is filled with the oil 9 due to the height difference. The unbonded sheath 1 and the PC steel strand 2 are warmed by the warm water 6, and the oil 9 does not solidify in the middle. When pouring, the oil 9 may be pressurized at a low pressure and injected into the unbonded sheath 1 depending on the situation that the oil 9 does not rotate well.

FIG. 2 shows the case where the unbonded sheath 1 wound in a spiral shape is placed in the high temperature tank 10. The air 11 is heated by the heater 12 in the tank 10. The high temperature tank 10 has an upper lid that can be opened and closed, and the end portion of the unbonded sheath 1 can be brought out from a hole formed in the upper lid. The unbonded sheath 1 may be warmed in the tank 10 and the oil 9 may be poured from the exposed end.

FIGS. 3 and 4 show the case where the unbonded sheath 1 is formed into another curved shape, and a part or all of the hot water tank 4 having a relatively shallow depth forms a ring. This is the case when it is wound in a curved shape. 5 and 6 show:
The unbonded sheath 1 is bent into a U-shaped curve and the hot water tank 4
When soaked in. In the above processing method, only one sheath 1 may be put in the hot water tank 4 or the high temperature tank 10. However, for example, as shown in FIG. It is considered that a more general work procedure is to put the oil in the high temperature tank 10 and then inject the rust preventive oil 9 sequentially. When using the anchor cable that has been unbonded as described above, the fixing length part 3 is passed through a fixing sheath made of stainless steel or the like, and the unbond sheath 1 is passed through a free length part sheath made of synthetic resin. 1 may also be used as it is as a free length sheath.

[0014]

The present invention has the above-mentioned structure and can obtain the following effects. Since the unbonded sheath is curved and placed in a hot water tank or high temperature tank, the space occupied by the hot water tank or high temperature tank can be reduced, and it can be processed even in an environment with a small space such as a cable processing factory or an on-site processing site. Is possible. Since a plurality of PC steel stranded wires are passed together through the unbonded sheath, the diameter of the sheath can be reduced, the diameter of the drilled hole can be reduced, and the excavation cost can be reduced. Since the unbonded sheath is placed in a hot water tank or a high temperature tank to be warmed, the heated oil does not solidify in the middle of the sheath, and the sheath is well filled with oil. After the sheath is filled with oil, both ends of the sheath are positioned above and pulled up from warm water or air for cooling, so that the oil does not spill and the filling of the sheath with oil is not impaired. Since the sheath is placed in warm water or high temperature air, not in oil, oil does not adhere to the outer periphery of the sheath and no oil removal work is required. The fluidized oil flows into the sheath over the entire length by injecting it with the pouring port raised, and the sheath can be better filled by pressurizing and injecting at a low pressure.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an implementation state of an unbonding processing method.

FIG. 2 is an explanatory diagram of another implementation state of the unbonding processing method.

FIG. 3 is a plan view of another embodiment in which an andon sheath is immersed in a hot water tank.

FIG. 4 is a side view of the embodiment of FIG.

FIG. 5 is a plan view of another embodiment in which an unbonded sheath is immersed in a warm water tank.

6 is a side view of the embodiment of FIG.

FIG. 7 is a side view of an unbonded sheath through an anchor cable.

FIG. 8 is a cross-sectional view of an unbonded sheath.

FIG. 9 is a cross-sectional view of a conventional unbonded cable.

FIG. 10 is an explanatory diagram showing a state where the unbonded sheath is immersed in an oil tank.

[Explanation of symbols]

 1 Unbonded sheath 2 Stranded PC steel wire 3 Fixing part 4 Hot water tank 5 Heater 6 Hot water 7 Rope 8 Spout fitting 9 Rust preventive oil 10 High temperature tank 11 Air 12 Heater

Claims (2)

(57) [Claims] 1. A portion of a plurality of PC steel strands is used as a free length portion, and the free length portion is inserted into an unbonded sheath made of synthetic resin to form a part or all of the free length portion into a curved shape. And immerse it in a warm water tank filled with warm water, inject rust-proof oil that has been fluidized by heating from one end of the unbonded sheath,
Unbonding method for anchor cable to cool the rust preventive oil in the unbond sheath and solidify it after the rust preventive oil is filled in the unbond sheath . 2. A part of a plurality of PC steel strands is used as a free length part, and the free length part is inserted into an unbonded sheath made of synthetic resin to form a part or all of the free length part into a curved shape. Put it in a high temperature tank filled with high temperature air, inject the rust preventive oil that has been heated and fluidized from one end of the unbonded sheath, and fill the unbonded sheath with the rust preventive oil. Anchor cable unbonding method that removes the rust-preventive oil in the unbonded sheath from the high temperature tank with the part positioned above and cools and solidifies it.