JP6807482B1 - Tendon's head fixation structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a head fixing structure of tendon, which has an excellent anticorrosion effect as compared with a conventional head fixing structure in which grease is used as an anticorrosion material and can reduce the frequency of replacement work of the anticorrosion material. At the time of construction, a head cap 5 covering a fixing member 1, 2, 3 and a tendon 9 is filled with a liquid material that solidifies with the passage of time, and under normal conditions, the fixing members 1, 2, Reference numeral 3 denotes a solid material 8 which is formed by solidifying the liquid and has flexibility and predetermined heat resistance. [Selection diagram] Fig. 1

Description

The present invention relates to a structure in which the head of a ground anchor (hereinafter referred to as "tendon") is fixed to the ground in a ground anchor construction method used for ground stabilization measures for slopes and slopes to prevent ground slips and the like. It is a thing.

In the ground anchor method, a tendon (sometimes called a tendon tension material or a strand) composed of a head, a free length part, and an anchor body is used.

The anchor body has a function of fixing the tendon to the ground by injecting cement grout. Further, the free length portion is a portion for making the tendon in a stretchable and free state.

The head is a part for fixing the tendon on the ground surface to a pressure receiving structure such as a glue frame or a pressure receiving plate. Tension the tendon with a jack and fix it to the pressure receiving structure using a jig such as an anchor head or a wedge. In the state where the head is fixed to the pressure receiving structure, a tensile force acts on the tendon. Then, since the tensile force exerts a compressive force on the ground as a reaction force, unstable behavior such as landslide can be suppressed.

As a structure for fixing the head of the tendon to the pressure receiving structure, for example, a structure disclosed in Japanese Patent Application Laid-Open No. 11-181768 (hereinafter referred to as a crimping grip screw fixing type) is known. In this crimping grip screw fixing type, a tubular rigid load-bearing body (hereinafter referred to as an apartment) having a screw groove engraved on the outer periphery is crimped to the head of a tendon and fixed to be fitted on the outer periphery of the apartment. The head is fixed to the pressure receiving structure via a bearing plate (anchor plate) arranged between the nut and the fixing nut and the pressure receiving structure. Further, since the fixing nut and the apartment are screwed together, the tensile force can be adjusted by adjusting the position of the fixing nut.

On the other hand, as another structure, for example, a structure disclosed in Japanese Patent Publication No. 7-25364 (hereinafter referred to as a wedge anchor head fixing type with a ring) is known. In this wedge anchor head fixing type with a ring, a disk-shaped fixing body (hereinafter referred to as an anchor head) and a wedge having a male screw formed on the outer circumference and penetrating a steel material insertion hole having a tapered opening into which a wedge can be inserted. Can be used to fix the head to the pressure receiving structure via a bearing plate arranged between the anchor head and the pressure receiving structure. Further, the tensile force can be adjusted by adjusting the position of the nut screwed on the outer circumference of the anchor head.

Further, regardless of the structure of the crimping grip screw fixing type and the wedge anchor head fixing type with a ring (hereinafter, these structures are collectively referred to as "head fixing structure"), the head fixing structure is used. Since the head is exposed to the ground surface and is easily corroded, the head treatment specified in "Geotechnical Society Standards Ground Anchor Design and Construction Standards, Explanation" is applied. Specifically, a member that fixes the head of Tendon (anchor head, wedge, condominium, nut, etc., hereinafter referred to as "fixing member") is covered with a head cap, and an anticorrosive material such as rust preventive oil is placed inside the cap. It is filled.

Japanese Unexamined Patent Publication No. 11-181768 Jitsufuku No. 7-25364

Japanese Geotechnical Society Standards Ground Anchor Design / Construction Standards, Commentary The Japanese Geotechnical Society

The anticorrosion material filled in the head cap does not hinder the expansion and contraction of the tendon, and when the cap is removed for inspection work, etc., it does not flow out to the surroundings and remains attached to the fixing member. Must be a thing. Grease that meets these requirements is widely used as an anticorrosion material.

However, the grease has extremely low fluidity, and it is difficult to fill the small gaps in the fixing member, and corrosion in the small gaps cannot be prevented, and there are cases where a sufficient anticorrosion effect is not achieved as a whole.

In addition, when grease is used as an anticorrosion material, it is oxidized by the influence of water invading through the gaps in the sheath covering the tendon and the air contained in the grease, and is deteriorated by being exposed to high temperatures due to sunlight, and over time. The anticorrosion effect is reduced. In order to maintain the anticorrosion function in the head fixing structure, it is necessary to replace the oxidatively deteriorated grease with new grease, but the service life of the grease is extremely short compared to the service life of the fixing member, and the replacement work There was a problem that the frequency of grease increased and it took time to maintain.

Furthermore, the head anchoring structure is often installed in places that are not easily reachable by humans, such as forests, steep lands, and sides of highways, and the replacement work may be subject to many restrictions. It was. Moreover, for the head fixing structure installed in the forest, it is necessary to completely collect the grease used for the replacement work without leaving it at the installation site in consideration of the influence on the natural environment. Therefore, there is a problem that it takes a lot of time and effort to carry out the replacement work.

Therefore, the present invention is superior in the anticorrosion effect to the conventional head fixing structure in which grease is used as the anticorrosion material, the frequency of the anticorrosion material replacement work can be reduced, and the replacement work becomes necessary. It is an object of the present invention to provide a head fixing structure of Tendon which can reduce the trouble.

In the head fixing structure of the tendon according to the present invention, at the time of construction, a liquid material that solidifies with the passage of time is filled in the head cap covering the fixing member through an injection port provided in the head cap. Under normal conditions, the fixing member is coated with a solid material having flexibility and predetermined heat resistance, which is formed by solidifying the liquid.

The inside of the head cap may be visually recognizable from the outside.

The fixing member may be subjected to a rust preventive treatment.

According to the head fixing structure of the tendon according to the present invention, the liquid material used as the anticorrosion material and solidifies with the passage of time becomes flexible in the state of the solid material covering the fixing member. Therefore, the extension and contraction of the tendon are not hindered, and when the cap is removed for inspection work or the like, the cap can be kept attached to the fixing member without flowing out to the surroundings. That is, it satisfies the properties required for the anticorrosion material in the head fixing structure. Then, when constructing the structure, it reaches a small gap of the fixing member, solidifies in a normal state, and covers the entire fixing member without leaving a gap, so that it has a higher anticorrosion effect than the conventional head fixing structure using grease. It will be excellent.

Further, air is removed from the periphery of the solid material covering the fixing member, and the solid material covering the fixing member is in a state of being shielded from the outside air, so that its oxidation is suppressed. Moreover, since the solid material covering the fixing member has a predetermined heat resistance, deterioration is suppressed even in a state of being exposed to a high temperature due to solar radiation. Therefore, the progress of oxidative deterioration is slower than that of grease, and the frequency of replacement work can be reduced.

Furthermore, since the solid material that coats the fixing member has flexibility, it does not break and scatter when it is removed from the fixing member, and even if the liquid material is accidentally leaked, it becomes a solidified state. It can be easily recovered. Therefore, the labor of replacement work can be reduced.

Furthermore, by making it possible to see the inside of the head cap from the outside, the inside of the head cap can be confirmed from the outside of the head cap, and the replacement work is performed only when necessary, so that unnecessary replacement work can be performed. Can be omitted. That is, the frequency of replacement work can be reduced.

Furthermore, if the fixing member is subjected to a rust preventive treatment, the contribution of the anticorrosive material to the anticorrosion of the fixing member is reduced. Therefore, the frequency of replacement work can be reduced.

It is a front view which shows the embodiment of the head fixing structure of the tendon which concerns on this invention. It is a front view which shows the other embodiment of the head fixing structure of the tendon which concerns on this invention. It is a front view which shows still another embodiment of the head fixing structure of the tendon which concerns on this invention.

An embodiment of the head fixing structure of the tendon according to the present invention will be described with reference to FIG.
In the embodiment shown in FIG. 1, an anchor head fixing type is adopted as the head fixing structure. That is, in this embodiment, a disk-shaped anchor head 1 and a wedge 2 having a tapered wedge receiving portion into which the wedge 2 can be inserted and penetrating the tendon insertion hole are used, and the anchor head 1 and the pressure receiving structure are used. The head of the tendon 9 is fixed to the pressure receiving structure via the bearing plate 4 arranged between them.

Further, on the outer circumference of the anchor head 1, a nut (hereinafter referred to as "adjustment ring 3") screwed with a male screw formed on the outer circumference of the anchor head 1 is fitted on the outer circumference of the anchor head 1. Then, it is said that the tensile force of the tendon 9 can be adjusted by adjusting the position of the adjusting ring 3. In FIG. 1, the male screw formed on the outer circumference of the anchor head 1 is not shown.

In this embodiment, the anchor head 1, the wedge 2, and the adjusting ring 3 correspond to the fixing member of the present invention. Then, these fixing members in a state where the tendon 9 is fixed are covered with the head cap 5 together with the end portion of the tendon 9.

Each of the constituent members of the wedge 2 is provided with a recess having a shape that matches the outer circumference of the tendon 9, and the recess is applied to the outer circumference of the tendon 9 to sandwich the tendon 9 between the two constituent members. As a result, the wedge 2 is arranged on the outer circumference of the tendon 9. Then, by fitting the wedge 2 into the wedge receiving port of the anchor head 1, the tendon 9 is fixed in a tense state. Since the shape of the wedge socket is known, the illustration and description will be omitted.

The tendon 9 is fitted with a water blocking member 6 that prevents water from entering through the gaps between the holes formed in the bearing plate 4. The wedge 2 is fixed to the end side of the tendon 9 with respect to the water blocking member 6.

The head cap 5 has an internal space for including the anchor head 1, the wedge 2, the adjusting ring 3, and the end portion (fixing member) of the tendon 9. The upper side of the internal space is closed and the lower side is opened, and a flange 51 is provided around the edge of the opening. Further, in the vicinity of the upper end of the peripheral wall 52, a window portion 53 for visually recognizing the internal space, an injection port 54 for anticorrosion material, and a discharge port 55 for injection work are provided.

The flange 51 can be screwed to the bearing plate 4. A seal ring is arranged on the lower surface of the flange 51. Then, it is in close contact with the bearing plate 4 while maintaining a watertight state.

In this embodiment, a cast aluminum product is used as the head cap 5, but the material is not limited as long as it has corrosion resistance, and it may be manufactured by a method suitable for the material to be adopted. For example, it may be a molded product of resin.

The space between the inner surface of the head cap 5 and the fixing member (anchor head 1, wedge 2, adjusting ring 3, and end of tendon 9) is filled with a solid material 8.

The solid material 8 is formed by filling the inside of the head cap 5 in a state of being closely fixed to the bearing plate 4 with a liquid material that solidifies with the passage of time through the injection port 54 and solidifying the material 8. .. It is said that the tendon 9 has flexibility that deforms according to expansion and contraction, and has heat resistance that does not deteriorate heat even in a high temperature environment brought about by sunlight.

In this embodiment, a known molding silicone is used for forming the solid material 8, but what was a liquid solidifies with the passage of time, and the solid material formed by solidification becomes flexible. Other materials may be used as long as they have a predetermined heat resistance. For example, other synthetic resin or rubber may be used. However, the solid material formed by using the molding silicone has a translucent property, and has an advantage that the state of the fixing member can be easily inspected through the window portion 53.

Further, in this embodiment, known steel products are used as the anchor head 1, the wedge 2, and the adjusting ring 3, but these may be subjected to a rust preventive treatment. There is no limitation on the type of plating applied as the rust preventive treatment, and electroless nickel plating, molten aluminum plating, low temperature black chrome plating and the like may be applied. However, the temperature at the time of plating needs to be within a range in which the hardness of the burnt accent does not decrease, and is preferably 90 to 95 ° C. Further, in order to prevent electrolytic corrosion, it is preferable to use the same type of metal.

In this embodiment, the anchor head fixing type structure is formed in which the anchor head 1, the wedge 2, and the adjusting ring 3 are used as fixing members, but the fixing members are not limited and are fitted on the condominium and the outer periphery of the condominium. A crimping grip screw fixing type structure may be used in which a fixing nut is used as a fixing member. FIG. 2 shows an embodiment of the crimping grip screw fixing type. In FIG. 2, substantially the same parts as those of the embodiment shown in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted or simplified.

In the embodiment shown in FIG. 2, a fixing nut 3 (the adjusting ring of the embodiment shown in FIG. 1) is attached to the condominium 7 formed by crimping a steel cylinder material having a male screw formed on the outer peripheral portion to the head of the tendon 9. (Corresponding to 3) is fitted, and the head of the tendon 9 is fixed to the pressure receiving structure via the fixing nut 3 and the bearing plate 4. In FIG. 2, the male screw formed on the outer circumference of the condominium 7 is not shown.

In this embodiment, the head cap 7 is assumed to be fixed to the bearing plate 4 by bolting, and has a bolt hole. In FIG. 1, the bolts for fixing the head cap 7 and the bolt holes formed in the bearing plate 4 are not shown.

A known steel product is used for the condominium 7, but a rust preventive treatment may be applied. Similar to the embodiment shown in FIG. 1, the type of plating is not limited, and electroless nickel plating, hot-dip aluminum plating, low-temperature black chrome plating, or the like may be applied. Further, it is an embodiment shown in FIG. 1 that the temperature at the time of plating is set within a range in which the hardness does not decrease due to burning, and that the fixing nut 3 and the apartment 7 are plated with the same type of metal in order to prevent electrolytic corrosion. Is the same as.

The fixing member of the present invention is not limited to the member used for holding the head of the tendon 9 in the embodiments shown in FIGS. 1 and 2. When other metal members are used to hold the head of the tendon 9, the members are also included in the fixing member of the present invention.

Further, in both of the embodiments shown in FIGS. 1 and 2, the head cap 5 is provided with a window portion 53 so that the inside can be visually recognized. However, the entire head cap 5 is made of a material having translucency. The inside may be visible from any part of the head cap 5. FIG. 3 shows an embodiment of an anchor head fixing type using a head cap made of a material having translucency as a whole. In FIG. 3, substantially the same parts as those of the embodiment shown in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted or simplified.

On the other hand, if the inside of the head cap 5 is not inspected from the outside, the window portion 53 may not be provided. For example, if the solid material 8 does not have translucency, the head cap 5 may not be provided with the window portion 53.

Further, in the embodiment shown in FIGS. 1 to 3, the injection port 54 of the anticorrosion material and the discharge port 55 for the injection work provided in the head cap 5 correspond to the procedure for filling the anticorrosion material. do it. For example, when a second cap that holds the anticorrosion material around the fixing member is used and the head cap 5 covers the fixing member while being arranged outside the second cap, the injection port 54 The discharge port 55 may be provided on the second cap, and does not need to be provided on the head cap 5.

1 Anchor head 2 Wedge 3 Adjustment ring (fixing nut)
4 Support plate 5 Head cap 6 Water stop member 7 Mansion 8 Solid material 9 Tendon 51 Flange 52 Peripheral wall 53 Window 54 Inlet 55 Outlet

Claims (3)

At the time of construction, the head cap covering the fixing member is filled with a liquid material that solidifies with the passage of time through an injection port provided in the head cap, and in a normal state, the fixing member is the liquid material. A head fixing structure of tendon, which is formed by solidifying and is coated with a solid material having flexibility and predetermined heat resistance. The head fixing structure of a tendon according to claim 1, wherein the head cap is capable of visually recognizing the inside from the outside. The head fixing structure of a tendon according to claim 1 or 2, wherein the fixing member is subjected to a rust preventive treatment.

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