JP4149299B2 - Electric pole grounding device and construction method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an anchor embedding method for embedding an anchor supporting a branch line of a utility pole in the ground .
[0002]
[Prior art]
The present applicant has disclosed anchors (underground anchors) suitable for supporting branch lines of utility poles such as distribution lines and telephone lines in Patent Documents 1 to 3. This anchor is configured by intermittently providing a spiral excavation blade on the tip side of a cast iron support rod embedded in the ground.
[0003]
The anchor has a size that matches the nature (hardness) of the ground where the utility pole is installed, and is buried at a set depth so as to obtain a predetermined tensile strength at the branch line. Yes. For this reason, the present applicant can easily measure the N value, which is an index representing the degree of hardness of the ground, in order to obtain materials for determining the type of anchor to be used and the embedding depth. Was proposed in Japanese Patent Application No. 2000-23876. This N value is calculated from the resistance of the ground generated when a hollow measuring instrument (sampler) having an outer diameter of 5.1 cm, an inner diameter of 3.5 cm, and a length of 81.0 cm is driven into the ground, as shown in JIS A1219. It is obtained from the number N of hits required to drop a hammer of 63.5 kg (about 622.3 N) from a height of 75 cm to the above measuring tool and drive the measuring tool 30 cm. is there.
[0004]
Now, the N value measuring tool according to the above proposal has a rod shape as a whole, has a mounting portion at one end in the longitudinal direction, and is tapered at the other end. A rotating machine capable of rotating the measuring tool and pressing the other end of the measuring tool toward the ground can be detachably mounted.
[0005]
The N value measuring tool will be described with reference to the drawings. FIG. 5 is a view showing the N value measuring tool 1, (a) is a front view thereof, and (b) is a top view thereof. This N value measuring tool 1 has a rod-shaped body 2 (a round bar having a maximum diameter of 50φ in the illustrated example) made of a thin bullet-shaped steel and having a circular cross section, and at one end thereof (the upper end in the illustrated example). A collar portion 3 having a diameter larger than the diameter of the rod-like body 2 is provided.
[0006]
The upper part of the collar part 3 is formed in the attachment part 4 which consists of a prism. The mounting portion 4 is provided with a hole 4a in a direction perpendicular to the axial direction. And when this attachment part 4 is inserted in rotary machines M, such as a rotation part of a digging pillar car, this hole 4a penetrates the pin which is not shown in figure to the hole 4a, and rotates N value measuring tool 1 Used for mounting on the machine M.
[0007]
The other end side (the lower side in the illustrated example) of the rod-like body 2 is tapered toward the other end, and is formed so that the N-value measuring tool 1 can easily bite into the ground G during measurement. This taper is formed between the other end portion (tip portion) and 300 mm when the length from the flange portion 3 to the other end portion of the N value measuring tool 1 is 1400 mm. Further, this tapered portion is subjected to quenching processing, and wear resistance and durability are achieved.
[0008]
In FIG. 5 (a), m, m... Are marks and are rod-shaped while maintaining a predetermined distance (100 mm in the illustrated example) from a predetermined distance (500 mm in the illustrated example) from the other end (tip). It is provided around the body 2. The mark m can be formed by paint, but it is preferably formed by welding overlay because it easily rubs against the ground (ground) during N value measurement.
[0009]
In order to perform the N value measurement of the ground G using the N value measuring tool 1, first, the attaching portion 4 of the N value measuring tool 1 is attached to the tip of the rotating machine M such as the rotating portion of the excavated pillar car. . Then, the tip (taper) of the N value measuring tool 1 is aligned with the measurement position of the ground G, and the N value measuring tool 1 is made substantially vertical, and a predetermined pressing force (for example, 800 kgf (about 7840 N)) is applied. Thus, the N value is determined according to how many rotations have been performed before insertion into a predetermined depth (for example, 50 cm).
[0010]
In the case of the N-value measuring tool 1 having the shape shown in the figure, when the number of revolutions until the N-value measuring tool 1 is inserted 50 cm into the ground is about four times, the N value is estimated to be about 10, and the number of revolutions is In the case of about 10 times, the N value is estimated to be about 25. Further, the N value can be estimated based on how many cm the N value measuring tool 1 is inserted at a predetermined rotation number, for example, 10 rotations. For example, the N value when about 38 cm is inserted at 10 rotations is estimated to be about 30, and the N value when about 28 cm is inserted at 10 rotations is estimated to be about 40. Such a correlation between the rotation speed and the N value is obtained based on a conversion table prepared in advance.
[0011]
After the above-described N value measurement, the N value measuring tool 1 is removed from the rotating machine M, an anchor that matches the measured N value is selected, and the selected anchor is mounted on the rotating machine M to embed the anchor. Is done. The type of anchor that is selected based on the measured N value is described in detail in Japanese Patent Application No. 2002-41028.
[0012]
[Patent Document 1]
JP 2000-1850 A [Patent Document 2]
JP 2001-59221 A [Patent Document 3]
Japanese Patent Laid-Open No. 2001-182058
[Problems to be solved by the invention]
By the way, some utility poles of distribution lines and telephone lines require grounding work. Such a power pole is provided with a grounding device that has a ground resistance value prescribed by law, in which an electrode rod is buried in the vicinity of the power pole, and the electricity collected on the power pole easily flows into the ground. In addition, when a predetermined ground resistance value cannot be obtained with only one electrode rod, a plurality of electrode rods may be embedded at predetermined intervals so as to satisfy the predetermined ground resistance value.
[0014]
Thus, a power pole that requires a grounding device may be provided with a support device that supports the power pole with a branch line. Therefore, for such a power pole, a grounding device is required in addition to the support device. In addition, it is not only necessary to perform the installation work of the support device and the installation work of the grounding device separately, but also the problem of complicating the surrounding of the power pole because a reinforcing branch line and a ground wire are provided around the power pole. was there.
[0015]
Therefore, the present inventor has proposed a utility pole grounding device that can solve the above problem, that is, a utility pole grounding device that can substantially reduce the number of grounding devices. The grounding device for a utility pole is an electrical pole support device in which a lower end portion of a branch line rod is coupled to an anchor buried in the ground, and a branch line of the utility pole is connected to the upper end portion of the branch line rod. In addition, a ground wire provided on the utility pole is connected so that the anchor serves as a ground electrode, and is wired to the ground up to the utility pole. The anchor has a spiral excavating blade and supports a branch line of a utility pole.
When an anchor that is a component of a utility pole support device is used as a ground electrode of a grounding device, the anchor not only needs to have sufficient tensile strength to reinforce the support capability of the utility pole, It is necessary to have a predetermined ground resistance value.
An object of the present invention is to provide an anchor embedding method that can satisfy the above two conditions that are originally required when an anchor which is a component of a support device is used as a ground electrode of a ground device .
[0016]
[Means for Solving the Problems]
To achieve the above object, the anchor embedded method according to the present invention has a helical drilling blade, and, in the anchor embedded method for burying an anchor supporting a branch of a telephone pole in the ground, buried in the anchor that in the ground, at the same time the whole shape is measured N values based on the rotational speed and pushed while rotating the conductive metal N measurement tool exhibiting a rod, the N value measured with the N-value measurement tool The ground resistance is measured between the auxiliary electrode separated from the tool by a predetermined distance, the ground resistance value at the insertion depth of the N value measuring tool is measured, and the N value when an appropriate ground resistance value is measured is obtained. The combined anchor is buried up to a depth when an appropriate grounding resistance value is measured.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. Figure 1 is a schematic configuration diagram of electric pole grounding device. In FIG. 1, “i” is a utility pole erected on the ground G. An anchor A embedded in the underground (or the ground, the same applies hereinafter) G, a branch bar rod having a lower end connected to the upper end portion of the anchor A, and an upper end of the branch rod B The support device comprised by the branch line C which connects a part and the upper end side of the utility pole i is provided, and the support strength of the utility pole is reinforced.
[0018]
Anchor A is disclosed in Japanese Patent Application Laid-Open Nos. 2000-1850, 2001-59221, and 2001-182058. This anchor A is made of cast iron and has a plurality of (four in the illustrated example) spiral excavating blades a2, a2,... It has the feature that it can be easily embedded by rotating it to an arbitrary depth of the underground G using the rotation mechanism of the digging column car used when standing. The outer diameter of the spiral excavating blades a2, a2,... Is smaller on the tip side (lower end in FIG. 1).
[0019]
In order to embed the anchor A at a predetermined depth in the ground G, a branch bar rod is attached to the top of the anchor A, and a tool (insertion pipe) (not shown) (not shown) (It is described in detail in Japanese Patent No. 271345), and the lower end of the tool is fitted into a square column provided on the top of the anchor, and the tool is rotated by an unillustrated drilling trolley. This is done by rotating the mechanism. Then, after the anchor A is buried at a predetermined depth in the ground G, when the tool is removed, as shown in FIG. 1, the tip end portion of the branch rod B appears on the ground. Next, a branch line C is attached to a ring portion b ′ (see FIG. 1) provided at the tip of the branch line rod b via a thimble (not shown).
[0020]
The branch line rod is covered with an electrically insulating synthetic resin film and is subjected to an insulation treatment as a feature of the ground device of the present invention. In addition, you may perform this insulation process of this branch line rod | rod by covering the surroundings of a branch line rod | rod with an insulation cover.
[0021]
In FIG. 1, L is a ground wire which is one element constituting a grounding device provided on the utility pole A, and one end side thereof is connected to the upper end portion of the anchor A as shown in detail in FIG. The other end side is attached to a predetermined member (not shown) of the upper end of the utility pole i, such as a transformer base.
[0022]
The ground wire L is buried in the underground G between the anchor A and the utility pole (i), and in the utility pole (i), is a space (not shown) provided at the center of the utility pole (a) at least at a predetermined height from the ground. Z). When the ground wire L is not disposed in the space provided in the axial center of the utility pole i, the ground wire L is provided on the side surface of the utility pole i via a band member.
[0023]
A structure for attaching the ground wire L to the anchor A will be described with reference to FIG. The attachment of the ground wire L to the anchor A is performed using an eye part A ′ for attaching a branch bar rod provided at the upper end of the anchor A. That is, a pair of aluminum (including aluminum alloy) terminals 10a and 10b are arranged on both sides of the eye part A ', and the screw shaft of the screw 11 is passed through a hole 10b' provided in one terminal 10b. Thereafter, the screw shaft is passed through the ring portion L ′ provided at the end of the ground wire L, the screw shaft is further passed through the eye portion A ′, and screwed into the screw hole 10a ′ of the other terminal 10a. Both terminals 10a and 10b are fixed to the eye part A ', and the ground wire L is electrically connected to the anchor A.
[0024]
As described above, when the ground wire L is attached to the anchor A via the aluminum terminals 10a and 10b, the terminals 10a and 10b are base metals rather than the cast iron anchor A. It has the feature that corrosion can be effectively prevented.
[0025]
As described above, when the anchor A, which is a component of the support device, is originally used as the ground electrode of the ground device, the anchor A must have sufficient tensile strength to reinforce the support capability of the utility pole i. In addition, the ground electrode must have a predetermined ground resistance value.
Therefore, the present inventors originally pursued an anchor burying method that can satisfy the above two conditions required when using the anchor A, which is a component of the support device, as the ground electrode of the ground device, At the same time as measuring the N value of the ground at the anchor A position, measure the grounding resistance value of the anchor A on the ground, and select an anchor that matches the hardness of the ground based on the measured values. The construction method to embed in the depth position was established.
[0026]
FIG. 3 is an explanatory diagram showing a measurement method for measuring the N value and measuring the ground resistance value (Ω) of the anchor A in the anchor embedding method according to the present invention. This N-value measurement is performed according to the description using FIG. At the time of measuring the N value, the ground resistance is measured every time the N value measuring tool 1 is inserted into the ground (ground) G at a predetermined depth (for example, 50 cm). More specifically, the lead wires 21, 21, between the N value measuring tool 1 and the two auxiliary electrode rods 20a, 20b that are sufficiently separated from the N value measuring tool 1 and inserted in advance to a sufficient depth. The ground resistance value (Ω) is measured by using a known resistance meter 22 connected to the lead wires 21, 21, and 21.
[0027]
FIG. 4 shows a case where the N value is measured and the ground resistance is measured using the above-described N value measuring tool 1 on the normal ground expected to have an N value of 5 to 10 in the site of the applicant's Toyokawa office. It is a graph. The graph of FIG. 4 also shows the grounding resistance value of the anchor selected by N value measurement (the diameter of the largest spiral excavating blade located at the upper part is 350φ).
[0028]
As is clear from FIG. 4, the N value is high from the ground surface to a predetermined depth (in the example of FIG. 4, the N value is about 10 cm at a depth of 100 cm), and the N value is low at a deeper depth. (In the example of FIG. 4, the N value is about 5), and the characteristics of the normal ground are well expressed.
[0029]
The ground resistance using the N-value measuring tool 1 of the measurement ground shown in FIG. 4 is about 70Ω at a depth deeper than 150 cm. Therefore, if the anchor is buried more than that depth, the ground resistance is 100Ω or less. It represents that the ground electrode can be secured. As apparent from the graph of FIG. 4, since the locus of the ground resistance of the N value measuring tool 1 for N value measurement and the locus of the ground resistance of the anchor substantially coincide, This shows that the grounding resistance value of the anchor also serving as an electrode can be predicted.
[0030]
It should be noted that an anchor having a tensile strength suitable for the N value is selected from the ground value indicating the N value and the ground resistance measured as described above, and the depth at which an appropriate ground resistance value is measured is selected. The anchor anchor depth when the anchor is selected and the selected anchor (the diameter of the uppermost spiral excavating blade at the top is 350φ) is embedded at the determined depth of 300 cm. 70.7 kN, which was sufficient as the tensile strength of the branch line of the utility pole.
[0031]
In the above embodiment, the power pole ground device insulates the branch rod of the power pole support device, connects the ground wire provided on the power pole so that the anchor of the power pole support device serves as a ground electrode, and Since the electric pole is wired in the ground, the configuration unique to the grounding device is not required other than the utility pole supporting device and the grounding wire, so that the grounding device can be substantially reduced. Therefore, the cost reduction effect of the ground device can be obtained. Further, the branch bar is connected to an anchor which is a ground electrode, but since it is insulated, safety during lightning strikes is ensured.
In addition, the anchor has a spiral excavation blade whose outer diameter gradually increases from the front end to the rear end around the tapered shaft, so that the anchor can be easily embedded and the spiral excavation blade has a large ground contact area. As a result, the anchor becomes a preferred ground electrode having a low ground resistance value.
Furthermore, a screw inserted through the ring connected to the end of the ground wire is inserted into one of the terminals arranged on both sides of the member for connecting to the support rod provided at the upper end of the anchor. In addition, the structure penetrates the member and is screwed into the other of the terminals to electrically connect the ground wire to the anchor. Therefore, a member for connecting to the support rod of the anchor is used. The ground wire can be easily connected. Further, since the anchor is usually made of cast iron, the anchor can be prevented from being corroded by making the terminal made of a base metal such as aluminum.
[0032]
【The invention's effect】
According to the present invention, in an anchor embedding method in which an anchor having a helical excavation blade and supporting a branch line of an electric pole is embedded in the ground, the entire shape of the anchor is embedded in the ground in which the anchor is embedded. The N-value measuring tool made of porous metal is pushed in while rotating, and the N value is measured based on the number of rotations. At the same time, the N-value measuring tool is grounded between the N-value measuring tool and the auxiliary electrode separated from the N-value measuring tool. resistance was measured to measure the ground resistance of the insertion depth of the N measurement tool, proper grounding resistance the anchor suitable for the N value when the proper grounding resistance value was measured was measured Since it embeds to the position of the depth of time, the anchor according to the N value of the said soil can be reliably embed | buried in the depth position from which an appropriate grounding resistance value is obtained. Therefore, it is possible to easily construct a supporting device having a reliable supporting strength and a grounding device having an appropriate grounding resistance on the utility pole standing on the soil.
[Brief description of the drawings]
1 is a schematic diagram of A over scan device.
FIG. 2 is a detailed view of the attachment of the ground wire to the anchor.
FIG. 3 is an explanatory diagram showing a method of N value measurement and ground resistance measurement.
FIG. 4 is a graph showing measurement results of ground resistance and N value.
5A and 5B are diagrams showing an N-value measuring tool, where FIG. 5A is a front view thereof, and FIG. 5B is a top view thereof.
[Explanation of symbols]
B Electric pole B Branch line C Branch line L Ground line A Anchor a2 Drilling blade G Underground (ground)
1 N value measuring tool 10a, 10b Terminal 11 Screw 22 Resistance meter A 'Member for connecting support rod to anchor (eye part)
L 'ring part

Claims (1)

In an anchor embedding method of embedding an anchor that has a spiral excavation blade and supports a branch line of a utility pole in the ground,
In the ground to be buried in the anchor, and at the same time the entire shape measuring the N value based on the rotational speed and pushed while rotating the conductive metal N measurement tool exhibiting a rod, the N value measured tool And the auxiliary electrode separated from the N value measuring tool by a predetermined distance, the ground resistance was measured at the insertion depth of the N value measuring tool, and an appropriate ground resistance value was measured. anchor buried wherein the embedding to the position of the depth at which proper grounding resistance the anchor suitable for the N value is measured at the time.

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