JP2009094024A - Buried earth, and earth material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an earth material which can secure a low earthing resistance without being buried deeply in the ground. <P>SOLUTION: The earth material 15 is constituted by laminating a copper sheet 11 of 20 to 50 μm in thickness and a nonwoven fabric 12 of 100 to 400 g/m<SP>2</SP>in basis weight with an adhesive 13. Since the copper sheet and the nonwoven fabric deform plastically, when the ground surface where the earth material is buried is leveled, the earth material 15 is pressed and deformed by earth and sand 18, increasing an effective contact area with the earth 17 and securing a low earthing resistance. The nonwoven fabric to be used is a needle punching felt in which a fibrous web composed of staple fibers of crimped synthetic fibers of 1 to 15 dtex in single fiber fineness is subjected to needle punching to entangle and fluffing the fibers. The copper sheet is preferably with irregular fine wrinkles 16. The earth material is folded with the nonwoven fabric inside, or two sheets of the earth material may be superposed with the nonwoven fabrics inside to make a double structure, further decreasing the earthing resistance. The earth material can serve simultaneously as a grass-proofing sheet. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention grounds electrical equipment and equipment to the ground and releases fault currents such as fault currents and lightning currents to the ground, and is also used as a weedproof sheet to prevent weed growth around utility poles and steel towers It relates to a possible earthing material.

  In order to effectively discharge the fault current to the ground, it is necessary to increase the contact area between the grounding material and the ground to reduce the grounding resistance. For this reason, the grounding material is buried deep in the ground and the grounding material and the ground are There are proposed a method of injecting a fluid conductive agent in between (for example, see Patent Document 1), and a method of connecting a ground wire to the tip of a ground material deeply buried in the ground (for example, see Patent Document 2). .

  Fabrics such as woven fabrics, warp knitted fabrics, and non-woven fabrics are used for the weedproof sheets (see, for example, Patent Documents 3 and 4).

JP 2001-326001 A JP 2002-231335 A JP 2002-281838 A (Patent No. 3526834) JP 2004-073146 A

  In order to embed the earth material deeply in the ground, a large facility is required, and since the earth material is also enlarged, the economic burden increases, and in urban areas, a space for piled up the earth and sand generated by digging holes for earth material It will be difficult to secure.

  With herbicidal sheets made of fabrics such as woven fabrics, warp knitted fabrics, and non-woven fabrics, plants take roots in the gaps between the fabrics and fibers, and they grow so much that they break down the fabrics and take a lot of effort to pull them out. Even if it can be pulled out, the weedproof sheet will be torn. And when a herbicidal agent or a defoliant is carried on a herbicidal sheet, there is a problem of underground contamination.

  Accordingly, a first object of the present invention is to obtain a grounding material that can ensure a low ground resistance without being buried deeply in the ground. The second object of the present invention is to obtain a grounding material that can also be used as a weedproof sheet.

The first feature of the present invention is that the grounding material 15 is configured by bonding a copper sheet 11 having a thickness of 20 to 50 μm and a nonwoven fabric 12 having a basis weight of 100 to 400 g / m ² with an adhesive 13.

  The second feature of the present invention is that, in addition to the first feature described above, needle punching is performed on a fiber web in which the nonwoven fabric 12 of the grounding material 15 is a short fiber of synthetic fiber having a single fiber fineness of 1 to 15 dtex. It is a needle punching felt which is made and entangled between fibers 14 and 14 to make it fluffy.

  The third feature of the present invention resides in that the copper sheet 11 of the ground material 15 has an uneven corrugation 16 in addition to any of the first and second features.

  The fourth feature of the present invention is that, in addition to any of the first, second, and third features, both front and back surfaces are copper sheets 11 and 11, and the front and back copper sheets 11 and 11 face each other. The non-woven fabrics 12 and 12 are bonded to the inner surface of each of the two to make a double.

  According to a fifth feature of the present invention, in addition to any of the first, second, third, and fourth features, the grounding material is bent in a manner that the copper sheet is directed vertically and outward, and is cylindrical. Is in the point that

  The sixth feature of the present invention is: (1) The grounding material 15 having any one of the first, second, and third features is embedded in the ground 17 with the copper sheet facing downward and the nonwoven fabric facing upward. (2) An intermediate layer 24 made of earth and sand 18 is laminated on the nonwoven fabric facing upward, and (3) gravel 23 having a particle size larger than the earth and sand 18 is included on the intermediate layer 24. The upper laminate 25 is laminated, and (4) a ground layer 26 made of earth and sand 18 having a particle size smaller than the gravel 23 of the upper laminate 25 is laminated below the grounding material 15 that directly touches the copper sheet. .

When the stretching stress acts on the nonwoven fabric 12, the stretching stress does not act on the continuous direction of the yarn like a woven fabric or a knitted fabric, and it is dispersed in the individual fine fibers constituting the yarn. The individual fibers that act and are displaced due to the stretching stress do not return to their original positions, and are more easily plastically deformed than woven fabrics and knitted fabrics. In particular, the needle punching felt 12 having a single fiber fineness of 1 to 15 dtex, and having a fiber web formed of a crimped synthetic short fiber that is needle-punched and interlaced between the fibers 14 and 14 is formed as follows: Each fiber 14 in the nonwoven fabric is easily displaced by receiving a slight external force, and is very easily plastically deformed.
On the other hand, the copper sheet 11 is easily plastically deformed as compared with other conductive materials as a physical property of copper, and is extremely easily plastically deformed because its thickness is as extremely thin as 20 to 50 μm.
For this reason, the grounding material 15 of the present invention is very easily bent and plastically deformed by a slight external force, and can be easily wound up into a cylindrical shape, and when it is wound up into the cylindrical shape, the grounding material 15 is interposed between the copper sheet 11 and the nonwoven fabric 12. The delamination due to the dimensional difference between the inner diameter and the outer diameter corresponding to the thickness of the copper sheet 11 does not occur, and the adhesive state between the copper sheet 11 and the nonwoven fabric 12 is maintained.

  When the earth material 15 is placed in the buried hole dug in the ground 17 and the earth and sand are backfilled and the ground surface 20 is pressed and hardened, the copper is pressed into each grain of the backfilled earth and sand 18 and finely rolled. The surface of the sheet 11 has fine irregular ridges 16 that are closely adhered to the copper sheet 11 as if each grain of earth and sand 18 fits into the irregular ridges 16, and the earth and sand 18 entangled with the nonwoven fabric 12 and the ground 17. The grounding material 15 is integrated.

  When the irregularity gavel 16 is generated, the nonwoven fabric 12 is plastically deformed according to the irregularity gavel 16, and at that time, the reaction force against the earth and sand grains 18 pressing the copper sheet 11 is It does not act from the nonwoven fabric 12 toward the copper sheet 11. And the nonwoven fabric 12 is comprised not by thread | yarn like a woven fabric and a knitted fabric, but by the myriad fibers which were divided separately, and there are no gaps and unevenness | corrugations like a weave or a stitch, and the whole surface is fiber fluff 19 The fluffy fiber fluff 19 and the adhesive 13 are united to form a tough film and adhere to the copper sheet 11, so that even if the copper sheet 11 is extremely thin, the earth and sand 18 The copper sheet 11 is not pressed by each grain and broken finely, or the copper sheet 11 is sandwiched between a gap such as a weave or a stitch and earth and sand, and is not sheared or cracked.

  Since the copper sheet 11 with the uneven corrugation 16 shaped in advance is finely stretched and deformed in accordance with the undulation curve shape of the corrugation corrugation 16, when the depression is depressed by the earth and sand grains 18, it is a raised portion before embedding. Recovers its original shape. On the other hand, when the bulge is pushed up from the surroundings and raised up, the hollow before embedding also restores the original shape. As a result, the local stress acting on the copper sheet 11 is absorbed and relaxed by the pre-shaped uneven corrugation 16 at the location where the corrugation 16 is newly generated by being pressed by the sand particles 18. Become. Therefore, even if the copper sheet 11 is extremely thin, cracks due to the earth and sand 18 to be refilled are avoided.

  Since the grounding material 15 of the present invention is in close contact with the earth and sand 18 to be refilled and plastically deforms, the grounding resistance with the ground 17 can be reduced. Therefore, it is not necessary to embed the earthing material 15 much deeper. Therefore, the earthing material 15 can be efficiently used without burying the earthing material 15 without requiring a large excavator or a large space for depositing the excavated earth and sand. Can be buried.

  Since the earthing material can be buried relatively shallow as described above, when the ground surface 20 backfilled with the earth and sand 18 is consolidated with a vibrator or the like, the tightening pressure to the ground surface 20 becomes a pressing force, and the earthing material is removed from the earth and sand 18. 15, the effective contact area between the grounding material 15 and the ground 17 can be increased.

  The grounding material 15 of the present invention is buried by supporting it with a utility pole or other support or a supporting member 21 (FIG. 1), or embedded without using the supporting member (21) (FIGS. 2 and 3). ). When embedding alone (FIG. 3), the nonwoven fabric 12 is interposed as an insulating material between the copper sheet 11 and the ground 17. In that respect, in the present invention, the double-sided structure in which the front and back sides are made of copper sheets 11 and 11, and the non-woven fabrics 12 and 12 are bonded to the inner surfaces of the front and back copper sheets 11 and 11 facing each other. Therefore, the nonwoven fabric 12 does not become an insulating material, and both the front and back surfaces of the grounding material 15 have contact areas with the ground 17, and the grounding resistance can be lowered even when buried shallowly. In this case, the grounding material 15 is pressed from both the front and back surfaces, and the joint surface 22 of the double nonwoven fabric 12 and 12 is bent and bent, so that the grounding material 15 is well adapted to the ground 17 and the grounding material 15 and the ground 17 There is no gap on the contact surface, and the ground resistance can be further reduced in this respect.

  When the grounding material 15 is formed in a cylindrical shape by bending the copper sheet 11 vertically and outward, the contact area with the ground 17 is widened even if the grounding material 15 is buried shallowly in a narrow land. The ground resistance can be lowered.

  Further, when the grounding material 15 is buried horizontally, the grounding material 26 is laid down with the copper sheet 11 facing downward and the nonwoven fabric 12 facing upward on the ground layer 26 prepared by the earth and sand 18 having a small particle size, and the upward facing thereof. When an intermediate layer 24 made of earth and sand 18 having a fine particle size is laminated on the nonwoven fabric 12 and the upper laminate 25 including gravel 23 having a coarse particle size is laminated on the intermediate layer 24, the coarse gravel of the upper laminate 25 is obtained. Since 23 overlaps and the copper sheet 11 is strongly pressed against the base layer 26, the contact area with the ground 17 can be widened, and the ground resistance can be lowered.

  When the grounding material 15 is buried horizontally in such a manner, the copper sheet 11 blocks the grounding material 15 so that the plant does not penetrate the grounding material 15 and lower the root, and the grounding material 15 also serves as a weedproof sheet. Therefore, when the grounding material 15 is embedded around the utility pole, the steel tower, etc., it is not necessary to install a weedproof sheet around it.

  As described above, the grounding material 15 of the present invention is well-familiar with the ground 17 and can ensure a low grounding resistance without being buried deeply, and is a large facility for digging a buried hole in which the grounding material is buried. However, it does not require a large space to pile up the earth and sand generated by the digging, and it can also be used as a weedproof sheet, so it can be used in the vicinity of utility poles and steel towers that require grassproof construction. Convenient to the buried earth.

  In the present invention, the thickness of the nonwoven fabric 12 is not regarded as a particular problem. This is because in the needle punching felt (12) in which the fiber web, which is a short fiber of a synthetic fiber having a single fiber fineness of 1 to 15 dtex, is subjected to needle punching and interlaced between fibers 14 and 14, and is fluffed. This is because when the soil 20 is consolidated, the nonwoven fabric (needle punching felt) 12 is pressed by the backfilled earth and sand 18 to have a predetermined thickness according to the basis weight.

However, when the fineness of the short fibers 14 exceeds 15 dtex or when the basis weight of the nonwoven fabric 12 exceeds 400 g / m ² , it is difficult to reduce the bulk to a predetermined thickness only by solidifying the ground surface 20. And when the nonwoven fabric shrinks to a predetermined thickness as time passes, a gap is generated between the grounding material 15 and the ground 17 by the amount of the shrinkage, so that the grounding occurs as time passes. The resistance will gradually increase. On the contrary, when the fineness of the short fibers 14 is less than 1 dtex, or when the basis weight of the nonwoven fabric 12 is less than 100 g / m ² , the function of the nonwoven fabric 12 as a crack generation alleviating material of the copper sheet 11 is lowered. Further, in the present invention, the thickness of the copper sheet 11 is set to 50 μm or less in order to easily generate the uneven corrugation 16 on the copper sheet 11, but if the thickness is too thin, the copper sheet 11 is easily cracked.

Considering these points, the thickness of the copper sheet 11 is 20 to 40 μm, preferably around 30 μm (25 to 35 μm), the basis weight of the nonwoven fabric 12 is 150 to 300 g / m ² , and the fineness of the short fibers 14 is 3 It is desired to be ˜8 dtex. From the viewpoint of recycling, it is desirable to use polyester fiber for the nonwoven fabric 12. Since the adhesive 13 is superior to other resins in terms of corrosion resistance, a heat-fusible polyolefin resin is preferably used.

  As shown in FIG. 1, the grounding material 15 can be wound around and embedded in a column 21, or can be embedded alone without using the column (21) as shown in FIGS. 2 and 3. Further, as shown in FIG. 1 and FIG. 2, the grounding material 15 is embedded with the copper sheet 11 oriented vertically, and as shown in FIG. 3, the copper sheet 11 is also used horizontally as a weedproof sheet. It can also be buried.

  When the copper sheet 11 is embedded horizontally, as shown in FIG. 3, the grounding material 15 is formed into a fixed plate shape having a vertical and horizontal dimension of 1 m or less, the nonwoven fabric 12 is faced upward, and the periphery is overlapped to form the ground layer 26. Are arranged so as to be spread over, and earth and sand 18 are deposited on the non-woven fabric 12 and an intermediate layer 24 is laminated, and gravel 23 having a particle size of 20 mm or more is deposited on the intermediate layer 24 and an upper laminate 24 is laminated. Good. The particle size of the earth and sand 18 on the surface of the base layer 26 that directly contacts the copper sheet 11 is set to 1 mm or less. The upper laminate 24 is laminated after the intermediate layer 24 is consolidated.

  The gravel 23 is applied as a weight that strongly presses the copper sheet 11 against the lower earth and sand 18 to eliminate the gap between the copper sheet and the ground, and increases the contact area between the copper sheet and the ground. For this purpose, gravel 23 having a fine particle size is deposited on the intermediate layer 24 on the nonwoven fabric 12 and then the particle size of the gravel to be deposited is gradually increased so that gravel having a large particle size appears on the ground surface 20. .

  As shown in FIG. 1, when the grounding material 15 is formed in a cylindrical shape and the copper sheet 11 is used vertically, the grounding material is not in a cylindrical shape but in a polygonal cross-sectional shape such as a triangle or a pentagon (star shape). 15 can be deformed and embedded. In that case, the polygonal cylindrical cavity can be filled with a mixture of a conductive material such as carbon powder, carbon fiber, and stainless steel and earth and sand instead of the support column (21).

  In the case where such a polygonal cross-sectional shape is assembled and buried, and earth and sand are filled in the cavity, the grounding material 15 is preferably formed in a double structure as shown in FIG. In order to make the grounding material 15 into a double structure, the single grounding material 15 may be folded with the nonwoven fabric 12 inside, or the two grounding materials 15 and 15 are overlapped with the nonwoven fabric 12 and 12 inside. May be.

  As shown in FIG. 1 and FIG. 2, even when the grounding material 15 is embedded with the copper sheet 11 oriented vertically, the particle size of the earth and sand 18 that directly touches the copper sheet 11 is set to 1 mm or less, and It is preferable to deposit gravel (barras) 23 having a particle diameter of 20 mm or more on the ground surface 20.

[Comparative example]
A grounding resistance measurement test was performed three times by measuring the grounding resistance by burying a commercially available earthing rod in which a copper core was plated on an iron core having a diameter of 10 mm, a length of 1500 mm, and a surface area of 0.47 m ² . The average ground resistance in the three ground resistance measurement tests was 125Ω.

[Example]
A needle punching felt nonwoven fabric 12 having a basis weight of 240 g / m ² composed of a 30 μm thick copper sheet 11 and a crimped polyester short fiber 14 having a single fiber fineness of 5 dtex is bonded via a hot-melt type polypropylene adhesive 13. A grounding material 15 having a vertical and horizontal dimension of 360 mm × 1320 mm and a surface area of 0.47 m ² was prepared. The ground material is wound around a vinyl chloride resin tube (21) having an outer diameter of 420 mm (overall circumference 1320 mm) with a copper sheet facing outward, and buried in the ground 17 as shown in FIG. The ground resistance measurement test was performed three times. The average ground resistance in the three ground resistance measurement tests was 85Ω.

[Evaluation]
As described above, the grounding resistance between the grounding material of the present invention (Example) and the ground is 85Ω, whereas the grounding resistance between the commercially available grounding rod (Comparative Example) and the ground is 125Ω, The grounding resistance of the grounding material of the present invention is 70% or less of the grounding resistance of a commercially available grounding rod, and it is confirmed that the present invention is practical in that it is not necessary to embed deeply when the grounding material of the present invention is used. It was done.

It is a perspective view of the buried ground which concerns on this invention, and is enlarging and enclosing a part in a circle. It is a perspective view of the buried ground which concerns on this invention, and is enlarging and enclosing a part in a circle. It is a perspective view of the buried ground which concerns on this invention, and is enlarging and enclosing a part in a circle.

Explanation of symbols

11: Copper sheet 12: Non-woven fabric 13: Adhesive 14: Fiber 15: Ground material 16: Concavity and convexity 17: Earth 18: Earth and sand 19: Fiber fluff 20: Ground surface 21: Support material (support)
22: Joint surface 23: Gravel

Claims (6)

(A) A grounding material (15) formed by bonding a copper sheet (11) having a thickness of 20 to 50 μm and a nonwoven fabric (12) having a basis weight of 100 to 400 g / m ² with an adhesive (13), the copper sheet (11). It is embedded in the earth 17 with the nonwoven fabric (12) facing upward,
(B) On the nonwoven fabric (12), an intermediate layer (24) consisting of earth and sand (18) and an upper laminate (25) including gravel (23) are sequentially laminated,
(C) A base layer (26) made of earth and sand (18) is laminated under the copper sheet (11),
(D) Embedded ground in which the particle size of gravel (23) included in the upper laminate (25) is larger than the particle size of earth and sand (18) of the intermediate layer (24) and the base layer (26). A grounding material (15) formed by bonding a copper sheet (11) having a thickness of 20 to 50 μm and a non-woven fabric (12) having a basis weight of 100 to 400 g / m ² with an adhesive (13), the copper sheet (11) is directed vertically. An embedded ground that is bent in a cylindrical shape toward the outside and is embedded in the ground (17). A grounding material formed by bonding a copper sheet (11) having a thickness of 20 to 50 μm and a nonwoven fabric (12) having a basis weight of 100 to 400 g / m ² with an adhesive (13).   A non-woven fabric (12) is a needle punching felt in which a fiber web made of a short fiber of a synthetic fiber having a single fiber fineness of 1 to 15 dtex is subjected to needle punching and interlaced between fibers (14, 14) to make it fluffy. The grounding material according to claim 3.   The grounding material according to any one of claims 3 and 4, wherein the copper sheet (11) has uneven corrugations (16).   The front and back sides are made of copper sheets (11, 11), and the non-woven fabrics (12, 12) are bonded to the inner surfaces of the copper sheets (11, 11) on the front and back sides to form double layers. The grounding material according to any one of claims 4 and 5.

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