Ground anchor head and forming method for ground anchor head

Abstract

To provide a ground anchor head and a forming method for the ground anchor head, capable of expecting enhanced anti-corrosion effect and allowing easy removal of anti-corrosion material.SOLUTION: A ground anchor head in accordance with the present invention is provided with a nut part 3, a screw part 5 screwed in the nut part 3, a tendon 7 exposed from an end surface on the opposite side to the nut part 3 through the inside of the nut part 5, and a wedge part 8 arranged in a gap between the tendon 7 and the end surface, wherein the side surface of the nut part 3, the side surface of the screw part 5, the end surface of the nut part 3 including a gap between the wedge part 8 and an excess length part 7a of the tendon 7, and the excess length part 7a of the tendon 7 are covered with non-hardening silicone putty 12, 31, 34.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a ground anchor head and a method of forming a ground anchor head. [Background technology]

[0002] Conventionally, a ground anchor method has been known as a construction method for stabilizing buildings or ground, in which a wire is used to tension and fix the underground and ground plate. The basic structure of a ground anchor is broadly divided into an underground anchor part, a ground support plate, and a ground anchor head that holds a wire called a tendon on the ground. The ground anchor head refers to the part above the ground support plate. Many ground anchor heads are equipped with a protective cap to protect the ground anchor head from falling rocks, wind, rain, and dirt. The tendon includes both the part exposed above ground and the part buried underground, but in the following explanation, the part of the tendon exposed above ground may be simply called the tendon.

[0003] The ground anchor head is mainly composed of a nut portion, an anchor head screw portion (hereinafter referred to as the screw portion), an excess length portion of the tendon, a wedge portion, and a protective cap. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 2987404 [Patent Document 2] JP 2005-213335 A Summary of the Invention [Problem to be solved by the invention]

[0005] By the way, the material that makes up the ground anchor head is generally metal. Therefore, if the ground anchor head is directly exposed to the elements, the metal part may corrode even if a protective cap is attached. This is because rain penetrates through tiny gaps and water leaks from the ground along the tendon. In view of this situation, a more effective corrosion prevention method is desired.

[0006] As a corrosion prevention method, for example, a waterproof structure for the head of an anchor to be buried in the ground has been proposed, in which a thick collar is provided at the mouth of the outer sheath, a groove is formed in the inner circumference of the collar, a water-swelling rubber waterproof seal material is provided in the groove, and the synthetic resin sheath and the mouth of the outer sheath are sealed with the waterproof seal material (see Patent Document 1). However, this waterproof structure requires a dedicated design, so it cannot be applied to waterproofing and corrosion prevention of existing facilities. Also, inspection is only possible after removing the cap and removing the rust-preventive oil.

[0007] As another example of a corrosion prevention method, for example, a form in which the inside of a cap is filled with fluidized grease has been proposed (see Patent Document 2). However, since a dedicated design is required for filling with grease, it cannot be applied to all shapes of ground anchor heads. In addition, the fluidity of grease is extremely low. For this reason, it is difficult to fill small gaps in the fixing member with grease. For this reason, corrosion in small gaps cannot be prevented, and there are cases in which sufficient corrosion prevention effects are not achieved overall.

[0008] An object of the present invention is to provide a ground anchor head which can be expected to have a higher anticorrosive effect and from which the anticorrosive member can be easily removed, and a method of forming a ground anchor head. [Means for solving the problem]

[0009] (1) The ground anchor head according to the embodiment for achieving the above object is as follows: a nut portion, a threaded portion that screws into the nut portion, a tendon that passes through the inside of the threaded portion and is exposed from an end face opposite the nut portion, and a wedge portion that is disposed in a gap between the tendon and the end face; The sides of the nut portion, the sides of the threaded portion, and the end face of the nut portion including the gap between the wedge portion and the excess length of the tendon, and the excess length of the tendon are covered with non-curing silicone putty. (2) In another embodiment of the ground anchor head, the ground anchor head preferably includes a nut portion, a threaded portion that screws into the nut portion, a tendon that passes through the inside of the threaded portion and is exposed from an end face opposite to the nut portion, and a wedge portion that is disposed in a gap between the tendon and the end face, The end face of the nut portion, including the side of the nut portion, the side of the threaded portion, and the gap between the wedge portion and the excess portion of the tendon, may be covered with non-hardening silicone putty, the excess portion of the tendon may be inserted into a silicone rubber tube, and the opening of the tube may be sealed with the non-hardening silicone putty. (3) In a ground anchor head according to another embodiment, it is preferable that the silicone rubber tube has a hardness of 40 or more and 80 or less when measured based on Durometer Type A (Shore A) in accordance with JIS K 6253, and a total light transmittance of 60% or more when measured based on JIS K 7375. (4) In the ground anchor head according to another embodiment, the non-curing silicone putty preferably has a plasticity of 100 or more and 600 or less when the plasticity is measured based on ISO7323. (5) In the ground anchor head according to another embodiment, the non-curing silicone putty preferably has a total light transmittance of 60% or more in a measurement of the total light transmittance based on JIS K 7375. (6) In the ground anchor head according to another embodiment, it is preferable that at least a portion of the ground anchor head is made of transparent glass or a transparent resin body and is covered with a protective cap that allows the inside to be visually observed. (7) In the method for forming a ground anchor head according to the embodiment, the method includes a step of filling the end face of the nut portion, including the gap between the wedge portion and the excess portion of the tendon, and the excess portion of the tendon with non-curing silicone putty, and a step of covering the side surface of the nut portion and the side surface of the threaded portion with the non-curing silicone putty. (8) In another embodiment, a method for forming a ground anchor head includes the steps of filling an end face of the nut portion, including a gap between the wedge portion and the excess length of the tendon, with non-curing silicone putty, inserting a silicone rubber tube into the excess length of the tendon and sealing an opening of the tube with the non-curing silicone putty, and covering a side surface of the nut portion and a side surface of the threaded portion with the non-curing silicone putty. Effect of the Invention

[0010] According to the present invention, it is possible to provide a ground anchor head and a method of forming a ground anchor head which can be expected to have a higher anticorrosive effect and in which the anticorrosive member can be easily removed. [Brief description of the drawings]

[0011] [Figure 1] FIG. 2 is a side view of the ground anchor head according to the embodiment. [Diagram 2] 2A to 2C are diagrams for explaining a method of forming the ground anchor head shown in FIG. [Diagram 3] 2A to 2C are diagrams for explaining a method of forming the ground anchor head shown in FIG. [Figure 4] 2A to 2C are diagrams for explaining a method of forming the ground anchor head shown in FIG. [Diagram 5] 2A to 2C are diagrams for explaining a method of forming the ground anchor head shown in FIG. [Figure 6] 2A to 2C are diagrams for explaining a method of forming the ground anchor head shown in FIG. [Figure 7] 2A to 2C are diagrams for explaining a method of forming the ground anchor head shown in FIG. [Figure 8]2A to 2C are diagrams for explaining a method of forming the ground anchor head shown in FIG. [Figure 9] 2A to 2C are diagrams for explaining a method of forming the ground anchor head shown in FIG. [Figure 10] 2A to 2C are diagrams for explaining a method of forming the ground anchor head shown in FIG. [Figure 11] FIG. 2 is a diagram showing the completed ground anchor head portion. [Figure 12] A diagram showing the completed ground anchor head. [Figure 13] 13A and 13B are diagrams showing modified examples of the ground anchor head. [Figure 14] FIG. 12 is a view for explaining the anticorrosive removal work for the completed ground anchor head part shown in FIG. 11. [Figure 15] FIG. 12 is a view for explaining the anticorrosive removal work for the completed ground anchor head part shown in FIG. 11. [Figure 16] FIG. 12 is a view for explaining the anticorrosive removal work for the completed ground anchor head part shown in FIG. 11. [Figure 17] FIG. 12 is a view for explaining the anticorrosive removal work for the completed ground anchor head part shown in FIG. 11. [Figure 18] FIG. 12 is a view for explaining the anticorrosive removal work for the completed ground anchor head part shown in FIG. 11. [Figure 19] FIG. 12 is a view for explaining the anticorrosive removal work for the completed ground anchor head part shown in FIG. 11. [Figure 20] FIG. 12 is a view showing the ground anchor head part after the anticorrosive removal work has been completed for the completed ground anchor head part shown in FIG. 11. [Figure 21] Photographs showing the evaluation results of tests on three types of samples. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that the embodiment described below does not limit the invention according to each claim of the claims. In addition, not all of the elements and combinations described in the embodiment are necessarily essential to the solution of the present invention. For example, although the present embodiment describes a state in which a protective cap is placed, which will be described later, a state without a protective cap may also be used.

[0013] 1, the ground anchor head 1 according to this embodiment includes a ground anchor head portion 2 and a protective cap 14 for covering the ground anchor head portion 2. The ground anchor head portion 2 includes a hollow nut portion 3, a threaded portion 5 having a male thread formed on its outer periphery, a tendon group 6, a wedge portion 8, a rubber silicone tube 10, a non-hardening silicone putty 12, and sheet-shaped non-hardening silicone putties 31, 34.

[0014] Between the nut part 3 and the ground, a bearing plate 16, which is a pressure-receiving structure, is disposed. Between the nut part 3 and the bearing plate 16, a flange 15 having a through hole (not shown) and a recessed portion 15a, into which the nut part 3 is fitted, is interposed. The nut part 3 is a hollow donut-shaped member. A female thread is formed on the inner periphery of the member, which is screwed into the male thread of the threaded part 5. The nut part 3 is fitted into the threaded part 5 by screwing the male thread and the female thread. The axial position of the nut part 3 can be adjusted by rotating the nut part 3. This allows the tensile force of the tendon group 6 to be adjusted. Note that in FIG. 1, the male thread formed on the outer periphery of the threaded part 5 is omitted. The tendon group 6 is also composed of a plurality of tendons 7. In this embodiment, the number of tendons 7 is described as four, but the number is not limited to this.

[0015] The screw portion 5 has four tendon through holes (not shown). A wedge portion 8 is disposed at a position corresponding to each tendon through hole. The wedge portion 8 has a recess 8a having a shape that fits the outer circumference of the tendon 7. The recess 8a is placed on the outer circumference of the tendon 7, so that the tendon 7 is clamped by the recess 8a. The wedge portion 8 is fitted into a wedge socket (not shown) of the screw portion 5, so that the tendon 7 is in a tensioned state. The wedge portion 8 has an effect of preventing the force of the tendon 7 returning to the support plate 16 side due to vibration or the like. The function of the wedge portion 8 is a well-known function, so a detailed description is omitted here. Each tendon 7 is inserted into the corresponding tendon through hole of the screw portion 5 via the corresponding wedge portion 8, and extends into the ground below the support plate 16 through the hollow of the nut portion 3, the flange 15, and the through hole formed in the support plate 16.

[0016] The flange 15 can be screwed to the support plate 16. A seal ring (not shown) is arranged on the underside of the flange 15 to ensure close contact with the support plate 16 while maintaining a watertight state. The flange 15 and the support plate 16 are formed with a plurality of through holes (not shown) through which a plurality of tendons 7 can be inserted, but they may also be hollow to allow a plurality of tendons 7 to be inserted.

[0017] The excess part 7a of the tendon 7 exposed above the upper end surface of the wedge part 8 is covered with a silicone tube 10 having a transmittance that allows at least the inside to be seen. The axial length of the silicone tube 10 is approximately the same as the axial length of the excess part 7a. A sheet-like non-curing silicone putty 34 having a transmittance that allows at least the inside to be seen is formed (attached) so as to cover the entire side surface of the nut part 3. In addition, a sheet-like non-curing silicone putty 31 having a transmittance that allows at least the inside to be seen is formed (attached) so as to cover the entire side surface of the threaded part 5. Furthermore, a non-curing silicone putty 12 having a transmittance that allows at least the inside to be seen is formed so as to cover the outer periphery of the silicone tube 10, the opening of the silicone tube 10, the end surface of the threaded part 5, the gap between the wedge part 8 and the excess part 7a, and the gap between the wedge part 8 and the wedge part 8.

[0018] In this way, the entire periphery of the components (except the protective cap 14) constituting the ground anchor head 1 is covered without any gaps with the sheet-like non-curing silicone putty 31, 34 and the non-curing silicone putty 12, so that the anti-corrosion effect can be increased. The method of forming the silicone tube 10, the non-curing silicone putty 12 and the sheet-like non-curing silicone putty 31, 34, and the materials thereof will be described later.

[0019] The protective cap 14 is preferably made of transparent glass or transparent resin so that the inside can be seen.

[0020] (Modification) In the above example, the non-curing silicone putty 12 is formed to cover the outer periphery of the silicone tube 10, the opening of the silicone tube 10, the end face of the threaded portion 5, the gap between the wedge portion 8 and the extra length portion 7a, and the gap between the wedge portions 8 and the wedge portions 8. However, the non-curing silicone putty 12 may be formed to cover each tendon 7, the end face of the threaded portion 5, the gap between the wedge portion 8 and the extra length portion 7a, and the gap between the wedge portions 8 and the wedge portions 8, without covering each tendon 7 with the silicone tube 10. According to this modification, the non-curing silicone putty 12 is formed without covering the extra length portion 7a of the tendon 7 with the silicone tube 10, so that the work time for forming the anticorrosive member can be shortened.

[0021] [Non-hardening silicone putty and sheet-type non-hardening silicone putty] The non-curable silicone putty 12 and the sheet-like non-curable silicone putty 31, 34 are silicone rubber compositions that contain a diorganopolysiloxane represented by the following chemical formula (I) as the main material, but do not contain a component that exhibits curability in a sufficient amount for curing. In other words, the non-curable silicone putty 12 and the sheet-like non-curable silicone putty 31, 34 are not limited to those that do not contain any component that exhibits curability. Representative examples of components that exhibit curability are a crosslinking agent and / or a curing catalyst.

[0022] [ka] (R in formula (I) 1 is a hydrocarbon group having 1 to 10 carbon atoms. n in formula (I) is 1.98 to 2.02.

[0023] R in formula (I) 1is a hydrocarbon group having 1 to 10 carbon atoms, preferably 1 to 8 carbon atoms. Examples of the hydrocarbon group include an alkyl group, a cycloalkyl group, an alkenyl group, and an aryl group. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, and a butyl group. Examples of the cycloalkyl group include a cyclohexyl group. Examples of the alkenyl group include a vinyl group, an allyl group, a butenyl group, and a hexenyl group. Examples of the aryl group include a phenyl group and a tolyl group. In addition, R 1 The n in the formula (I) may be a group in which some or all of the hydrogen atoms of the hydrocarbon group have been substituted with halogen atoms, cyano groups, etc. In the formula (I), n is 1.98 to 2.02.

[0024] The kinetic viscosity of the diorganopolysiloxane at 25° C. is preferably 100 to 100,000,000 cSt, and more preferably 100,000 to 10,000,000 cSt. When the kinetic viscosity of the diorganopolysiloxane at 25° C. is within the above range, the diorganopolysiloxane has excellent handleability.

[0025] Although the filler is not essential, it can be suitably used for the purpose of reinforcing the non-curing silicone putty. Examples of the filler include reinforcing agents (fumed silica, precipitated silica, silica whose surface is hydrophobized with an organic silicon compound, quartz powder, talc, zeolite, bentonite, etc.), fibrous fillers (asbestos, glass fiber, organic fiber, etc.), basic fillers (calcium carbonate, zinc carbonate, zinc oxide, magnesium oxide, celite, etc.), and thickeners (MQ resin, rosin derivatives, etc.). Among these, it is preferable to use silica, calcium carbonate, and zeolite, and it is more preferable to use fumed silica and calcium carbonate whose surface is hydrophobized. The amount of the filler to be blended can be selected depending on the purpose and the type of filler, but it is within the range of 1 to 90% by volume, and preferably within the range of 5 to 60% by volume, based on the components.

[0026] The constituent materials of the non-curing silicone putty may contain, in addition to the main material and filler, a plasticizer, a heat-resistant agent, and the like.

[0027] The plasticity of the uncurable silicone putty is preferably 100 or more and 600 or less, as measured according to ISO 7323. The total light transmittance of the uncurable silicone putty is preferably 60% or more, as measured according to JIS K 7375.

[0028] [Silicone rubber tube] The silicone rubber tube is a cured silicone rubber tube, unlike the non-curable silicone putty. The curable silicone composition for producing the tube-shaped silicone rubber may contain the main material shown in the above formula (I) and the components required for curing, as well as the above-mentioned filler, plasticizer, heat resistance agent, etc. Here, the components required for curing may include, for example, a crosslinking agent and a curing catalyst. When the curable silicone composition is a photocurable composition, a photoinitiator may be included as a component required for curing.

[0029] The silicone rubber preferably has a hardness of 40 or more and 80 or less, as measured by durometer type A (Shore A) according to JIS K 6253. The silicone rubber preferably has a total light transmittance of 60% or more, as measured by JIS K 7375. It is preferable that the silicone rubber has both a hardness and a total light transmittance in the above ranges, but the silicone rubber may have only a hardness or only a total light transmittance in the above range.

[0030] [How to form a ground anchor head] A method for forming the ground anchor head 1 will be described in detail below with reference to FIGS. (1) As shown in FIG. 2, a clay-like non-hardening silicone putty 12 is molded to cover the periphery of the four wedge portions 8. (2) The tendon 7 is inserted into the through hole 21 of a bowl-shaped jig 20 having a through hole 21 formed at a position corresponding to the tendon 7, and pressure is applied vertically downward to push it in (see Figure 3: the non-curing silicone putty 12 is omitted in Figure 3), forming the non-curing silicone putty 12 covering the periphery of the wedge portion 8 into a disk shape (see Figure 4). (3) After that, the jig is removed, and the four exposed excess lengths 7a are covered with silicone tubes 10 (see FIG. 5), and the silicone tubes 10 are further pushed downward to bury the bottoms of the silicone tubes 10 in the non-curing silicone putty 12 (see FIG. 6). (4) The opening 24 of the silicone tube 10 is sealed with non-hardening silicone putty 12 (see FIG. 7). (5) A sheet-like member 30 consisting of a sheet-like non-curing silicone putty 31 and a peelable release film 32 attached to one side of the sheet-like non-curing silicone putty 31 is wrapped around the outer periphery of the screw portion 5 and fixed in place (see FIG. 8). (6) A sheet-like member 33 consisting of a sheet-like non-curing silicone putty 34 and a peelable release film 35 attached to one side of the sheet-like non-curing silicone putty 34 is wrapped around the outer periphery of the nut portion 3 and fixed in place (see Figure 9). (7) Thereafter, the release films 32, 35 are peeled off (see FIG. 10), and after the peeling, sheet-like non-curing silicone putties 31, 34 are formed on the outer peripheral surface of the nut portion 3 (see FIG. 11). Note that, regarding the film peeling operation, the release film 32 may be peeled off after wrapping the sheet-like member 30, and then the sheet-like member 33 may be wrapped around it, and then the release film 35 may be peeled off, or the sheet-like members 30 and 33 may be wrapped around it at the same time, and then the release films 32, 35 may be peeled off at the same time. (8) When the above-mentioned film peeling operation is completed, the ground anchor head part 2 is completed (see FIG. 11), and the anticorrosion process is finished. (9) The ground anchor head 2 is then covered with a protective cap 14 to complete the ground anchor head 1 (see Figure 12). [Corrosion prevention and removal process] (1) Peel off the sheet-like non-hardening silicone putty 34 attached to the outer periphery of the nut portion 3 (see FIG. 14). (2) Next, the sheet-like non-curing silicone putty 31 attached to the outer periphery of the threaded portion 5 is peeled off (see FIG. 15). (3) Next, the non-curing silicone putty 12 in the vicinity of the top of the threaded portion 5 including the wedge portion 8 is peeled off (see FIG. 16). (4) All of the silicone tubes 10 are removed from the corresponding tendons 7 using an elongated removal tool 40 (see FIG. 17). (5) The uncured silicone putty 12 remaining in the recessed portion 8a of the wedge portion 8 is removed using a removal tool 40 (see FIG. 19). Note that it is easier to remove the putty 12 by inserting the removal tool 40 into the recessed portion 8a and prying it up. (6) When all of the above-mentioned removal steps are completed, the anticorrosion removal work is finished. After the anticorrosion removal work is finished, the ground anchor head part 2a (see FIG. 20) that has not been subjected to anticorrosion treatment is subjected to predetermined maintenance and inspection. EXAMPLES

[0031] Next, examples of the present invention will be described in comparison with comparative examples. Note that the present invention is not limited to the following examples.

[0032] 1. Testing and Evaluation Methods The test was performed using a combined cycle test machine (manufactured by Suga Test Instruments) in accordance with JIS K 5600-7-9, and cycle D (performed in the order of (1) to (4) below) under the following conditions was repeatedly performed on Samples 1 to 3. Test cycle: 232 cycles Test time: 1392 hours (Hr) <Test subject> Sample 1 (Comparative example: blank): M16 bolt, L60mm, unplated (degreased) Sample 2 (Example 1): A silicone tube is placed over the bolt of Sample 1, and silicone putty is then applied over the entire bolt. Sample 3 (Example 2): The bolt of Sample 1 was entirely coated with non-hardening silicone putty (corresponding to the above-mentioned modified example). (1) Salt spray process Prepare a salt spray test solution with a concentration of sodium chloride (50±10) g / l and a solution pH range of 6.0 to 7.0, and perform salt spray on each sample for 0.5 hours at 30±2°C. (2) Wetting process Each sample is moistened for 1.5 hours at 95±3% Rh and 30±2°C. (3)Hot air drying process Each sample is dried with hot air for 2.0 hours at 50±2℃. (4) Drying process Dry each sample for 2.0 hours at 30±2℃.

[0033] 2. Evaluation results Figure 21 shows photographs of the evaluation results of the above tests. The photograph on the left shows the appearance of the bolt of sample 1 after the above tests were conducted, with the top photograph being the bolt's head and the bottom photograph being the bolt's side. The photograph in the middle shows the appearance of the bolt of sample 2 after the above tests were conducted, with the top photograph being a plan view and the bottom photograph being a side view. The photograph on the right shows the appearance of the bolt of sample 3 after the above tests were conducted, with the top photograph being a plan view and the bottom photograph being a side view.

[0034] As is clear from the comparison of Example 1, Example 2 and the Comparative Example in FIG. 21, no rust occurred at all in Example 1, and almost no rust occurred in Example 2, whereas rust swelling was observed in the Comparative Example.

[0035] The test was performed using a metal bolt, but the head of the ground anchor is also made of metal, so the evaluation of the above test can be applied to the present invention. Therefore, as is clear from the evaluation results of Example 2, the head of the ground anchor, in which the side of the nut part, the side of the threaded part, and the end face of the nut part including the gap between the wedge part and the excess length of the tendon are covered with non-curing silicone putty, can exhibit a higher anticorrosion effect.

[0036] Furthermore, a ground anchor head in which the side of the nut part, the side of the threaded part, and the end face of the nut part, including the gap between the wedge part and the excess part of the tendon, are covered with non-curing silicone putty, and in which the excess part of the tendon is inserted into a silicone rubber tube and the opening of the tube is sealed with non-curing silicone putty, can exert an even higher anticorrosion effect, as is clear from the evaluation results of Example 1. Furthermore, because the head of the ground anchor is simply covered with the non-curing silicone putty and the silicone tube, or with only the non-curing silicone putty, the work of removing the anticorrosive member becomes extremely easy compared to when a curable silicone rubber composition is applied to the head part and cured.

[0037] In addition, since the non-curing silicone putty and silicone tube are nearly transparent, visual inspection is possible without removing the cap, making it easy to inspect when repairs (maintenance) are required, such as re-tensioning the tendon. [Explanation of symbols]

[0038] 1···Ground anchor head, 2···Ground anchor head portion, 3···Nut portion, 5···Thread portion, 6, 7···Tendon, 7a···Extra length portion, 8···Wedge portion, 10···Silicone tube, 12···Non-hardening silicone putty, 14···Protective cap, 31, 34···Sheet-shaped non-hardening silicone putty.

Claims

1. A ground anchor head comprising a nut portion, a threaded portion that screws into the nut portion, a tendon that is exposed from an end face opposite to the nut portion through the inside of the threaded portion, and a wedge portion that is disposed in a gap between the tendon and the end face, A ground anchor head characterized in that the side of the nut portion, the side of the threaded portion, and the end face of the nut portion including the gap between the wedge portion and the excess portion of the tendon, and the excess portion of the tendon are covered with non-hardening silicone putty.

2. A ground anchor head comprising a nut portion, a threaded portion that screws into the nut portion, a tendon that is exposed from an end face opposite to the nut portion through the inside of the threaded portion, and a wedge portion that is disposed in a gap between the tendon and the end face, A ground anchor head characterized in that the end face of the nut portion, including the side face of the nut portion, the side face of the threaded portion, and the gap between the wedge portion and the excess portion of the tendon, are covered with non-hardening silicone putty, the excess portion of the tendon is inserted into a silicone rubber tube, and the opening of the tube is sealed with non-hardening silicone putty.

3. 3. The ground anchor head according to claim 2, characterized in that the silicone rubber tube has a hardness of 40 or more and 80 or less when measured based on durometer type A (Shore A) in accordance with JIS K 6253, and a total light transmittance of 60% or more when measured based on JIS K 7375.

4. 4. The ground anchor head according to claim 1, wherein the non-curing silicone putty has a plasticity of 100 or more and 600 or less in a plasticity measurement based on ISO 7323.

5. 4. The ground anchor head according to claim 1, wherein the non-curing silicone putty has a total light transmittance of 60% or more in a measurement of total light transmittance based on JIS K 7375.

6. 4. The ground anchor head according to claim 1, characterized in that at least a portion of the ground anchor head is made of transparent glass or a transparent resin body and is covered with a protective cap that allows the inside to be visually observed.

7. 2. A method of forming the ground anchor head of claim 1, comprising the steps of: filling the end surface of the nut portion, including the gap between the wedge portion and the excess portion of the tendon, and the excess portion of the tendon with a non-curing silicone putty; covering a side surface of the nut portion and a side surface of the screw portion with a non-curing silicone putty; 13. A method for forming a ground anchor head comprising:

8. 3. A method of forming a ground anchor head according to claim 2, comprising the steps of: filling the end surface of the nut portion, including the gap between the wedge portion and the excess portion of the tendon, with a non-curing silicone putty; a step of inserting a silicone rubber tube into the excess portion of the tendon and sealing an opening of the tube with a non-curing silicone putty; covering a side surface of the nut portion and a side surface of the screw portion with a non-curing silicone putty; 13. A method for forming a ground anchor head comprising:

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