JPH11144778A - Ground electrode and its work execution method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ground electrode and its work execution method in which problems of working property, term of works and cost of works can be solved by arranging a conductive polar material on a cylindrical molded reducing material for ground resistance reduction. SOLUTION: A ground electrode 11 has a cylindrically prescasted ground resistance reducing material 12, and a conductive polar material 13 arranged as a core material. A hollow part 14 opened in the upper and lower end surfaces is formed in the center part of the reducing material, and the upper end part of the polar material 13 is protruded from the upper end surface of the reducing material 12 to connect ground line to a connecting part 15. As the reducing material 12, conductive concrete is used. The polar material 13 is formed into a basket opened in the upper and lower ends by a spiral bar 17 wound on a cylindrically arranged shaft bar 16. The shaft bar 16 and the spiral bar 17 consist of copper material or steel material. In the construction of the ground electrode 11, a circular sectional excavated hole is bored in the ground by a boring machine or the like, the precasted ground electrode 11 is inserted thereto, and the ground line is connected to the connecting part 15. The outer diameter of the reducing material 11 is increased, and the length is reduced to reduce the cost of works, so that the total cost can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ground electrode used for grounding an electric line and a method of constructing the same.

[0002]

2. Description of the Related Art In general, grounding means for protecting human bodies, facilities, and the like is provided on electric power lines for electric power and communication. This grounding means is buried underground with a copper grounding rod as a grounding pole.

In the case of soft ground, it is possible to directly drive the grounding rod into the ground. However, in the hardened rock ground, as shown in FIG. After drilling a hole 1 having a diameter of about 70 to 80 mm by an excavator such as a boring machine and the like, a grounding rod 2 coated with copper having a diameter of about 10 to 14 mm is inserted into the hole 1, and the grounding rod 2 is connected to the power transmission line. And the like, and a grounding wire 4 is connected thereto, and a flow-reducing material 5 for reducing grounding resistance is injected around the grounding rod 2 to fill the hole 1 back.

[0004]

In such a conventional grounding pole using the grounding rod 2, it is necessary to excavate deeply to obtain a specified value, and drilling work is not easy. In addition, elongated hole 1
The workability is not good because the grounding rod 2 is installed deep in the area. Furthermore, since a large amount of the reducing material 5 is used or special equipment is required, there is a problem in terms of construction time and construction cost, such as a problem in economy.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a grounding electrode capable of solving the problems of workability, construction period and construction cost, and a method of constructing the same.

[0006]

According to the first aspect of the present invention, a reduction member for reducing grounding resistance formed into a cylindrical shape and a conductive pole material provided on the reduction member are provided. The ground electrode provided.

[0007] By increasing the outer diameter of the cylinder of the reduction material formed into a cylindrical shape, even if the length of the reduction material in the axial direction is shortened, that is, even if the excavation depth of the ground is made shallow, the surrounding material may be reduced. A sufficient contact area with the ground can be secured, and the ground resistance value is reduced. Further, by increasing the inner diameter of the cylinder, the amount of the reducing material is reduced.

According to a second aspect of the present invention, the reduction member in the grounding electrode according to the first aspect is formed by precasting into a cylindrical shape.

[0009] By the precast molding, the labor of on-site construction of the reduction material and the pole material is omitted, and the workability is improved. The reduction material formed into a cylindrical shape corresponds to a circular construction cross section when drilling and excavating hard ground, and reduces the amount of backfill material used when embedding a ground electrode in an excavated portion.

According to a third aspect of the present invention, there is provided a grounding electrode according to the first or second aspect, wherein the pole material comprises a plurality of shafts arranged in a cylindrical shape, and a spiral wound around these shafts. Thus, it is formed in a basket shape.

The pole material formed in a cage shape by the shaft muscle and the spiral muscle arranged in a cylindrical shape facilitates the cylindrical formation of the reducing material.

According to a fourth aspect of the present invention, there is provided a drilling hole for burying a grounding electrode in the ground, and the grounding electrode according to any one of claims 1 to 3 is inserted into the drilling hole. This is a construction method of a ground electrode in which a gap between the ground electrode and the ground electrode is filled with a backfill material including a water retention material.

The water retention material keeps a constant moisture between the ground electrode and the ground so that a stable ground resistance value can be obtained over a long period of time.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to an embodiment shown in FIGS.

FIGS. 1 and 2 show a ground electrode according to the present invention.
11, a reduction member 12 for reducing grounding resistance, which is precast in a cylindrical shape, and a conductive pole material 13 provided as a core material inside the reduction member 12 are provided.

A hollow portion 14 having upper and lower end faces opened is formed at the center of the reducing material 12, and the upper end of the pole material 13 projects slightly from the upper end face of the reducing material 12 to connect a ground line. Connection section 15 for connection.

As the reducing material 12, for example, conductive concrete, ettringite, carbon, carbon fiber or steel fiber is used.

The conductive concrete or ettringite can be cured by directly mixing with water.
In addition, since carbon, carbon fiber, or steel fiber is not cured alone, it is used by mixing with a curable substance such as cement or resin.

The pole member 13 is formed in a cage shape having upper and lower ends opened by a plurality of shaft bars 16 arranged in a cylindrical shape and a spiral bar 17 wound around these shaft bars 16. The shaft 16 and the spiral 17 are made of copper, steel, iron, or the like.

When the ground electrode 11 is manufactured, first, a pole material 13 as a core material is formed in a cylindrical cage shape by a shaft bar 16 and a helical bar 17, and the pole member 13 is formed in a cylindrical shape. The reducing material 12 is set in the formed mold, and the reducing material 12 is poured into the mold and cured, thereby pre-casting the reducing material 12 into a cylindrical shape. Thereby, the pole material 13 is formed so as to be surrounded by the reduction material 12.

By this precast molding, the labor for on-site construction of the reducing material 12 and the pole material 13 is omitted, and the workability is improved. In addition, this precast molding is efficient if performed by, for example, a centrifugal molding method in which a cylindrical mold is rotated.

The pole member 13 formed in a cage shape by the plurality of shaft bars 16 and the helical bars 17 wound thereon as described above.
Has the advantage that it is easy to maintain a constant shape inside the reduction material 12 when molding it, but the pole material is not limited to the cylindrical cage shape, only the shaft muscle may be used, or only the spiral muscle Sometimes it is good.

Next, FIG. 3 shows a method of constructing the ground electrode 11 according to the present invention. A drill hole 19 having a circular cross section for burying the ground electrode is drilled in the ground 18 by a boring machine or the like. Then, the ground electrode 11 of the precast molding is inserted, and the ground wire 21 is connected to the connection portion 15 of the ground electrode 11.

Further, a backfill material 22 is provided in a gap between the inner peripheral surface of the excavation hole 19 of the ground 18 and the outer peripheral surface of the ground electrode 11. This backfill material 22 is made of only soil, a powdery or granular water retention material alone, a mixture of soil and a powdery or granular water retention material, or a sheet-like water retention material attached to the outer peripheral surface of the ground electrode 11. And so on.

As the water retention material, for example, a water absorbing material such as a water absorbing polymer or a water absorbing sponge is used, and if necessary, the backfill material 22 is used around the grounding electrode 11 as described above so that the grounding electrode 11 and the water absorbing material can be used. There is an advantage that a certain amount of water is held between the ground 18 and a stable ground resistance value can be obtained over a long period of time.

Similarly, the backfill material 23 is also filled in the upper part and the inside of the ground electrode 11. The backfill material 23 is only soil, a powdery or granular water retaining material, or a mixture of soil and a powdery or granular water retaining material.

The cylindrical reduction material 12 corresponds to the circular cross section of the excavation hole 19 when a hard ground such as rock is drilled by a boring machine or the like. In this case, the amount of the backfill material 22 used can be reduced.

By reducing the axial length of the reduction member 12 by increasing the outer diameter of the cylinder of the reduction member 12 formed into a cylindrical shape, that is, by reducing the excavation depth of the ground 18, Also,
A sufficient contact area with the surrounding ground can be secured, and the ground resistance value is reduced. Further, by increasing the inner diameter of the cylinder, the material of the reducing material 12 can be reduced.

As described above, the cylindrical precast product in which the center of the ground electrode 11 which does not affect the ground resistance is hollowed out from the conventional ground electrode construction method in which the reducing material 5 having fluidity is injected into the hole 1 at the site. Although the excavation cross-sectional area is larger than that of the conventional grounding method by switching to the grounding method using, the depth can be made as shallow as possible, reducing construction costs and improving workability. The overall cost can be reduced by shortening the construction period.

It is to be noted that the reducing material 12 is a part of the pole material 13.
Precast molding may be performed in such a state that it is exposed on the outer peripheral surface of 12, for example.

[0031]

Next, FIG. 4 shows an experimental facility for measuring the ground resistance of the ground electrode 11.

A measuring device main body formed in a box shape by a copper plate
A sand 32 as a virtual ground is put inside 31, and a conventional ground rod and a cylindrical ground electrode 11 using various reducing materials according to the present invention are inserted into the sand 32 as test specimens, respectively. ,
Then, a ground resistance meter 33 is electrically connected between the ground electrode 11 and the measuring device main body 31, and a ground resistance value between the ground electrode 11 and the measuring device main body 31 is measured by the ground resistance meter 33. did. In the following, the conventional grounding rod is indicated as (I),
Cylindrical grounding electrode using three types of reducing materials according to the present invention
11 is indicated as (II), (III), or (IV).

(I) is a copper-coated bar having a length of 300 mm and a diameter of 10 mm.

The material 12 for reducing the grounding electrodes (II), (III), and (IV) used as a test body in this experiment is a cylindrical body having an outer diameter of 200 mm, an inner diameter of 106 mm, and a total length of 300 mm. Are eight cylindrically arranged lengths of 300 mm and a diameter of 1
0 mm axial streaks SD295 and a diameter 6 wound around these shafts with an axial pitch of 50 mm and a winding outer diameter of 170 mm
It is formed in a cage shape with upper and lower ends opened by a spiral muscle SWM-B of mm. The shaft bar SD295 is made of steel bars for reinforced concrete (JIS G 3112) and spiral bar SWM.
-B is an iron wire (JIS G 3532).

The reducing material (II) is obtained by kneading and mixing carbon powder (Sun Kosher Co., Ltd., trade name: Sun Earth), cement and water at a weight ratio of 2: 1: 0.8. is there.

The reducing agent (III) is obtained by kneading a mixture of carbon fiber and cement (Kansai Tec Co., Ltd., trade name: Dodencrete) and water at a weight ratio of 1: 0.6 to 0.8. It was cast.

The reducing material of (IV) is a steel fiber (Coral Co., Ltd., trade name: Tessa 5530), cement, sand, water, a water reducing agent (Mighty 150), and an antifoaming agent (adecanol). , Weight ratio 26: 100: 24
The mixture was kneaded and cast at 0: 35: 6: 6.

The measurement results of the ground resistance are shown in Table 1 below.

[0039]

[Table 1] As a result, as shown in Table 1, the ground resistance value obtained in the experiment was 1841 (Ω) of the conventional ground rod (I), and the ground electrodes (II) (III) (IV) ) Is 386
(Ω), 424 (Ω), and 419 (Ω), which could be reduced to about に 対 し て of the grounding rod (I) of the conventional method.

The steel fiber mortar of the grounding electrode (IV) is a mortar containing steel fiber, which is not present in conventional reducing materials. It is inexpensive as compared with the reduction material.

[0041]

According to the first aspect of the present invention, a grounding electrode provided with a reducing member formed into a cylindrical shape for reducing grounding resistance, and a conductive pole material provided on the reducing member. Therefore, even if the axial length of the reduction material is reduced by increasing the outer diameter of the reduction material tube formed into a cylindrical shape, a sufficient contact area with the surrounding ground is secured. In addition, the ground resistance value can be reduced, and the ground excavation depth can be made shallow, so that workability such as excavation work and ground pole installation work can be improved, and the problems of construction period and construction cost can be solved. Further, by increasing the inner diameter of the cylinder, the material of the reducing material can be reduced, and the economic efficiency can be improved.

According to the second aspect of the present invention, by the precast molding, the labor for on-site construction of the reduction material and the electrode material can be omitted, the workability can be improved, and the quality of the reduction material and the electrode material can be kept constant. it can. Furthermore, the reduction material formed into a cylindrical shape can correspond to a circular construction cross section when drilling and excavating hard ground, and the amount of backfill material used when embedding a ground electrode in an excavated portion can be reduced.

According to the third aspect of the present invention, the pole material formed in a cage shape by the plurality of shafts arranged in a cylindrical shape and the spiral wound around these shafts reduces the reduction material. Can be easily formed into a cylindrical shape.

According to the fourth aspect of the present invention, an excavation hole for burying a ground electrode is drilled in the ground, and the ground electrode according to any one of claims 1 to 3 is inserted into the excavation hole. The grounding electrode is filled with backfill containing water-retaining material in the gap between the grounding electrode and the grounding electrode, so that the water-retaining material can maintain a certain amount of water between the grounding electrode and the ground. A stable ground resistance value can be obtained.

[Brief description of the drawings]

FIG. 1 is a vertical sectional view of a ground electrode according to the present invention.

FIG. 2 is a horizontal sectional view of the same ground electrode.

FIG. 3 is a cross-sectional view showing a method for applying the ground electrode according to the first embodiment.

FIG. 4 is a sectional view of an experimental facility for measuring a ground resistance value of the ground electrode according to the first embodiment.

FIG. 5 is a cross-sectional view showing a construction state of a conventional ground electrode.

[Explanation of symbols]

 11 Grounding pole 12 Reduction material 13 Polar material 16 Axle bar 17 Spiral bar 18 Ground 19 Drilled hole 22 Backfill material including water retention material

Claims (4)

[Claims] 1. A grounding electrode comprising: a cylindrically shaped reducing material for reducing grounding resistance; and a conductive pole material disposed on the reducing material. 2. The grounding electrode according to claim 1, wherein the reducing material is precast in a cylindrical shape. 3. The pole material is formed in a basket shape by a plurality of shafts arranged in a cylindrical shape and a spiral wound around these shafts. The described ground pole. 4. A drilling hole for burying a grounding electrode is drilled in the ground, and the grounding electrode according to claim 1 is inserted into the drilling hole to retain water in a gap between the ground and the grounding electrode. A method for constructing a ground electrode, characterized by filling a backfill material containing a material.