JPH0516550B2 - - Google Patents
Info
- Publication number
- JPH0516550B2 JPH0516550B2 JP60178724A JP17872485A JPH0516550B2 JP H0516550 B2 JPH0516550 B2 JP H0516550B2 JP 60178724 A JP60178724 A JP 60178724A JP 17872485 A JP17872485 A JP 17872485A JP H0516550 B2 JPH0516550 B2 JP H0516550B2
- Authority
- JP
- Japan
- Prior art keywords
- steel pipe
- wall
- current
- ground
- magnetic field
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 229910000831 Steel Inorganic materials 0.000 claims description 69
- 239000010959 steel Substances 0.000 claims description 69
- 230000003014 reinforcing effect Effects 0.000 claims description 58
- 238000001514 detection method Methods 0.000 claims description 15
- 239000002184 metal Substances 0.000 claims description 11
- 229910052751 metal Inorganic materials 0.000 claims description 11
- 230000000149 penetrating effect Effects 0.000 claims description 4
- 238000010586 diagram Methods 0.000 description 8
- 238000000034 method Methods 0.000 description 7
- 230000005389 magnetism Effects 0.000 description 6
- 229910001294 Reinforcing steel Inorganic materials 0.000 description 5
- 125000006850 spacer group Chemical group 0.000 description 4
- 238000005259 measurement Methods 0.000 description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- 239000010426 asphalt Substances 0.000 description 1
- 238000004210 cathodic protection Methods 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- 230000002787 reinforcement Effects 0.000 description 1
Landscapes
- Measurement Of Resistance Or Impedance (AREA)
- Testing Electric Properties And Detecting Electric Faults (AREA)
- Geophysics And Detection Of Objects (AREA)
Description
【発明の詳細な説明】
［産業上の利用分野］
本発明は、塗覆装鋼管等がビル建屋等の鉄筋入
り壁を貫通している場合に壁内で鋼管が鉄筋に電
気的に接触していることを検出する鋼管の壁内金
属接触検出装置に関する。[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a method for preventing electrical contact between the steel pipe and the reinforcing steel within the wall when a coated steel pipe or the like penetrates a reinforced wall of a building or the like. This invention relates to a metal contact detection device within the wall of a steel pipe.
［従来の技術］
外部からビル建屋内にガス管等の塗覆装鋼管を
引込む場合や建屋内で各部屋に配管する場合等に
おいては、鉄筋入りの壁を貫通させてこれ等塗覆
装鋼管を配管する必要がある。この場合、壁の貫
通部分で塗覆装鋼管が内部の鉄筋に電気的に接触
すると、ビル建屋そのものの接地抵抗が少ないの
で、たとえ塗覆装鋼管に電気防食処理を施したと
しても、接触部分および鉄筋を介して腐蝕電流が
大地へ流れ込む。したがつて、塗覆装鋼管の腐蝕
速度が増加し、塗覆装鋼管の耐久寿命が短くなり
つたり、最悪の場合ガス漏れ等の懸念が発生す
る。[Conventional technology] When bringing coated steel pipes such as gas pipes into a building from the outside, or when piping them to each room within the building, the coated steel pipes are passed through reinforced walls. need to be piped. In this case, if the coated steel pipe comes into electrical contact with the internal reinforcing steel at the part that penetrates the wall, the grounding resistance of the building itself is low, so even if the coated steel pipe is given cathodic protection, the contact area will be Corrosive current flows into the ground through the reinforcing steel. Therefore, the rate of corrosion of the coated steel pipe increases, the durability of the coated steel pipe becomes shorter, and in the worst case, there is a risk of gas leakage.
このような問題を回避するために、新規にビル
を建築する場合は鋼管が鉄筋に直接電気的に接触
しないように細心の注意を払つて配管作業を行な
うが、既設ビル建屋においては鋼管の壁の貫通部
において、電気的に内部の鉄筋に接触しているか
否かを外部から検出する必要がある。 To avoid such problems, when constructing a new building, the piping work must be done with great care to ensure that the steel pipes do not come into direct electrical contact with the reinforcing bars; however, in existing buildings, the steel pipes It is necessary to detect from the outside whether or not the penetration part is electrically in contact with the internal reinforcing steel.
このように既設のビルにおける壁内での接触の
有無を検出する方法の一つとして、鋼管の接地抵
抗を測定する方法がある。この接地抵抗を測定す
る方法は、第８図に示すように行なう。すなわち
地中に埋設されたガス管等の塗覆装鋼管１が、下
端が同じく地表面２下に埋設されたビル建屋の壁
３を貫通して屋内に導かれており、この塗覆装鋼
管１と大地間の抵抗値を抵抗測定器４で測定す
る。そして、塗覆装鋼管１が壁３内でこの壁３内
に配設された鉄筋５と電気的に接触していなけれ
ば前記抵抗値は大きな値であり、塗覆装鋼管１の
塗覆装が剥げ鉄筋５と電気的に接触していれば、
一般に鉄筋５は接地されているので、塗覆装鋼管
１は鉄筋５を介して接地されることになるので、
前記抵抗値は小さくなる。したがつて、塗覆装鋼
管１が鉄筋５に電気的に接触しているか否かを検
出できる。 One method of detecting the presence or absence of contact within the walls of an existing building is to measure the ground resistance of steel pipes. The method for measuring this ground resistance is as shown in FIG. That is, a coated steel pipe 1 such as a gas pipe buried underground is led indoors by penetrating the wall 3 of a building whose lower end is also buried below the ground surface 2. 1 and the ground using a resistance measuring device 4. If the coated steel pipe 1 is not in electrical contact with the reinforcing bars 5 disposed within the wall 3, the resistance value is a large value, and the coating of the coated steel pipe 1 is If is in electrical contact with the stripped reinforcing bar 5,
Generally, the reinforcing bars 5 are grounded, so the coated steel pipe 1 will be grounded via the reinforcing bars 5.
The resistance value becomes smaller. Therefore, it is possible to detect whether the coated steel pipe 1 is in electrical contact with the reinforcing bars 5 or not.
また、第９図に示すように、地表面２の電位分
布を測定することによつて、塗覆装鋼管１と鉄筋
５との間の電気的接触を検出する検出法がある。
すなわち、電圧印加装置７でもつて塗覆装鋼管１
と地表面２との間に電圧を印加する。そして、塗
覆装鋼管１が鉄筋５に電気的接触をしていたなら
ば、その接触部近傍での地表面２の電位分布に
「窪み」又は「突起」等の変化が生じる。 Furthermore, as shown in FIG. 9, there is a detection method that detects electrical contact between the coated steel pipe 1 and the reinforcing bars 5 by measuring the potential distribution on the ground surface 2.
That is, even if the voltage application device 7
A voltage is applied between the ground surface 2 and the ground surface 2. If the coated steel pipe 1 is in electrical contact with the reinforcing bar 5, a change such as a "dent" or "protrusion" will occur in the potential distribution on the ground surface 2 near the contact point.
［発明が解決しようとする問題点］
しかしながら上述した各検出方法においても次
のような問題があつた。すなわち、最初の接地抵
抗を測定する方法においては、既設ビルの場合塗
覆装鋼管１は壁３の貫通部分以外で人為的に接地
されている可能性があるので、測定された抵抗値
が小さいから塗覆装鋼管１が鉄筋５と電気的に接
触しているとは必ずしも断言できない問題があ
る。したがつて検出結果に信頼性が持てない。[Problems to be Solved by the Invention] However, each of the above-mentioned detection methods also has the following problems. In other words, in the first method of measuring ground resistance, in the case of an existing building, the coated steel pipe 1 may be artificially grounded at a place other than the part where it penetrates the wall 3, so the measured resistance value is small. Therefore, there is a problem in that it cannot necessarily be determined that the coated steel pipe 1 is in electrical contact with the reinforcing bar 5. Therefore, the detection results are not reliable.
また、地表面２の電位分布を測定する方法にお
いては、塗覆装鋼管１が鉄筋５に接触した場合の
接触抵抗の値に比較して鉄筋５の接地抵抗の値が
非常に小さいので、塗覆装鋼管１が鉄筋５に接触
したことに起因する前記電位分布の変化は微少で
あるので、検出が非常に難しい。また、地表面２
はアスフアルト舗装されている場合が多いので、
電位分布の変化を精度良く測定することはさらに
困難であつた。 In addition, in the method of measuring the potential distribution on the ground surface 2, since the value of the ground resistance of the reinforcing bars 5 is very small compared to the value of contact resistance when the coated steel pipe 1 contacts the reinforcing bars 5, Since the change in the potential distribution caused by the covered steel pipe 1 coming into contact with the reinforcing bar 5 is minute, it is very difficult to detect. Also, ground surface 2
are often paved with asphalt,
It was even more difficult to accurately measure changes in potential distribution.
また、以上２つの検出方法の他に、パイプロケ
ータを使用する方法もあるが誘導電流の影響を受
け易くまだ実用には至つていない。 In addition to the above two detection methods, there is also a method using a pipe locator, but this method is susceptible to induced currents and has not yet been put to practical use.
本発明はこのような事情に基づいてなされたも
のであり、その目的とするところは、鋼管が鉄筋
に電気的接触したときに鉄筋に流れる電流によつ
て形成される磁界を検出することによつて、壁表
面から非接触で簡単にかつ確実に鋼管が鉄筋に接
触したことを検出でき、信頼性を向上できる鋼管
の壁内金属接触検出装置を提供することにある。 The present invention was made based on these circumstances, and its purpose is to detect the magnetic field formed by the current flowing through the reinforcing bars when a steel pipe makes electrical contact with the reinforcing bars. Therefore, it is an object of the present invention to provide a metal contact detection device in a wall of a steel pipe that can easily and reliably detect contact of a steel pipe with a reinforcing bar without contacting the wall surface, and can improve reliability.
［問題点を解決するための手段］
本発明の鋼管の壁内金属接触検出装置は、鋼管
と大地間に電流源を設ることによつて、鉄筋が内
在する壁を貫通する鋼管を電流帰路として大地を
電流往路とする電流回路を形成し、互いに一定の
位置関係を保持しながら壁面に沿つて移動制御さ
れる一対の磁気センサでもつてそれぞれ壁面に直
交する磁界を検出し、差動増幅器でもつてこれ等
一対の磁気センサにて検出された各磁界の差を増
幅し、さらに記録計でもつて差動増幅器の出力信
号を記録するようにしたものである。[Means for Solving the Problems] The metal contact detection device in the wall of a steel pipe of the present invention establishes a current return path through a steel pipe that penetrates a wall containing reinforcing bars by providing a current source between the steel pipe and the ground. A current circuit is formed with the ground as the current path, and a pair of magnetic sensors that are controlled to move along the wall while maintaining a constant positional relationship detect the magnetic field perpendicular to the wall, and a differential amplifier can also be used. The difference between the magnetic fields detected by the pair of magnetic sensors is then amplified, and the recorder records the output signal of the differential amplifier.
［作用］
このように構成された鋼管の壁内金属接触検出
装置であれば、壁を貫通する鋼管を電流帰路とし
大地を電流往路とする電流回路が形成されてい
る。そして、鋼管が壁内の鉄筋に電気的に接触す
るとこの接触部分を介して接触された鉄筋に接地
電流が流れ、この接地電流に起因してこの鉄筋廻
りに磁界が形成される。この鉄筋廻りの磁界の方
向は壁表面に直交しているので、壁表面に沿つて
移動制御される一対の磁気センサで検出される。
なお、前記電流回路を形成する鉄管廻りに形成さ
れる磁界の方向は壁表面に平行しているので上記
各磁気センサで検出されることはない。また、磁
気センサを２個設けて検出された磁界の差を増幅
しているのは地磁気の影響を除去するためであ
る。したがつて、前記一対の磁気センサを一定の
位置関係を維持した状態で壁表面に沿つて移動し
ながら、前記差動増幅器の出力信号を監視して、
この出力信号が大きく変化すれば鋼管が鉄筋に電
気的接触していることになる。[Function] In the metal contact detection device in the wall of a steel pipe configured as described above, a current circuit is formed in which the steel pipe penetrating the wall is used as a current return path and the earth is used as a current outgoing path. Then, when the steel pipe electrically contacts the reinforcing bars in the wall, a grounding current flows through the contacted reinforcing bars through this contact portion, and a magnetic field is formed around the reinforcing bars due to this grounding current. Since the direction of the magnetic field around the reinforcing bars is perpendicular to the wall surface, it is detected by a pair of magnetic sensors whose movement is controlled along the wall surface.
Incidentally, since the direction of the magnetic field formed around the iron pipe forming the current circuit is parallel to the wall surface, it is not detected by each of the magnetic sensors. Furthermore, the reason why two magnetic sensors are provided and the difference between the detected magnetic fields is amplified is to eliminate the influence of earth's magnetism. Therefore, while moving the pair of magnetic sensors along the wall surface while maintaining a constant positional relationship, monitoring the output signal of the differential amplifier,
If this output signal changes significantly, it means that the steel pipe is in electrical contact with the reinforcing steel.
［実施例］
以下本発明の一実施例を図面を用いて説明す
る。[Example] An example of the present invention will be described below with reference to the drawings.
第１図は実施例の鋼管の壁内金属接触検出装置
の概略構成を示す模式図である。図中１１は例え
ばビル家屋のコンクリート製の壁であり、図示し
ないがこの壁１１の下端は地表面下に埋設されて
いる。また、壁１１の中心部には補強材として複
数の鉄筋１２が上下方向に配設されている。そし
て、例えばガス管等の塗覆装鋼管からなる鋼管１
３が壁１１を壁表面１４に対してほぼ直角に貫通
している。この鋼管１３における壁１１の手前側
部分の塗覆装を剥いだ金属面と大地間にはバツテ
リからなる電流源１５が図示極性に接続されてい
る。また、鋼管１３における壁１１の後方側部分
は直接大地に接地されている。したがつて、電流
源１５、鋼管１３、大地とで壁１１を貫通する鋼
管１３を電流帰路とし大地を電流往路とする電流
回路が形成される。 FIG. 1 is a schematic diagram showing a schematic configuration of a metal contact detection device in the wall of a steel pipe according to an embodiment. In the figure, 11 is a concrete wall of a building, for example, and although not shown, the lower end of this wall 11 is buried under the ground surface. Further, a plurality of reinforcing bars 12 are arranged in the vertical direction at the center of the wall 11 as reinforcing members. A steel pipe 1 made of a coated steel pipe such as a gas pipe, for example.
3 passes through the wall 11 approximately at right angles to the wall surface 14. A current source 15 consisting of a battery is connected between the uncoated metal surface of the near side of the wall 11 of the steel pipe 13 and the ground in the polarity shown. Further, the rear portion of the wall 11 in the steel pipe 13 is directly grounded to the earth. Therefore, a current circuit is formed between the current source 15, the steel pipe 13, and the ground, with the steel pipe 13 penetrating the wall 11 serving as a current return path, and the ground serving as a current outgoing path.
また、壁１１の壁表面１４にはこの壁表面１４
に沿つてＹ軸方向に移動制御される一対の磁気セ
ンサ１６ａ，１６ｂが配設される。これら一対の
磁気センサ１６ａ，１６ｂは相互の位置関係を常
に一定に保持するためにスペーサ１７の両端に固
定されている。さらに各磁気センサ１６ａ，１６
ｂは鋼管１３の長手方向、すなわち壁表面１４に
直交する方向の磁界のみを検出するように構成さ
れており、各磁気センサ１６ａ，１６ｂの検出信
号はそれぞれ差動増幅器１８の（＋）側入力端子
および（−）側入力端子へ入力される。さらに差
動増幅器１８の出力信号は記録計１９へ入力され
て記録紙上に記録される。そして、測定時にはス
ペーサ１７にて相互間隔距離がＬに固定された一
対の磁気センサ１６ａ，１６ｂをＹ軸方向に移動
しながら記録計１９に記録された差動増幅器１８
の出力信号レベルの変化を観察する。そして、信
号レベルが大きく変化すると鋼管１３が鉄筋１２
に電気的に接触していると判断する。 Moreover, the wall surface 14 of the wall 11 has this wall surface 14
A pair of magnetic sensors 16a and 16b whose movement is controlled in the Y-axis direction along the Y-axis is provided. These pair of magnetic sensors 16a, 16b are fixed to both ends of the spacer 17 in order to maintain a constant mutual positional relationship. Furthermore, each magnetic sensor 16a, 16
b is configured to detect only the magnetic field in the longitudinal direction of the steel pipe 13, that is, in the direction orthogonal to the wall surface 14, and the detection signals of each magnetic sensor 16a, 16b are input to the (+) side of the differential amplifier 18. input terminal and (-) side input terminal. Furthermore, the output signal of the differential amplifier 18 is input to a recorder 19 and recorded on recording paper. During measurement, the pair of magnetic sensors 16a and 16b whose mutual spacing distance is fixed to L by the spacer 17 is moved in the Y-axis direction, and the differential amplifier 18 is recorded on the recorder 19.
Observe the change in the output signal level. Then, when the signal level changes significantly, the steel pipe 13 changes to the reinforcing bar 12.
It is determined that there is electrical contact with the
第２図は実施例の検出装置の動作原理を説明す
るための透視図である。すなわち、壁１１内には
縦方向の鉄筋１２ａ〜１２ｅの他に、横方向の鉄
筋２０ａ〜２０ｅが配設されており、両方向の鉄
筋１２，２０は網目（メツシユ）状に組まれてい
る。そして、今仮に鋼管１３が中央の鉄筋１２ｃ
に電気的に接触していたとする。そして、電流源
１５の電圧をＥ、鋼管１３の電流源１５側の接地
抵抗をR1、鋼管１３の反電流源１５側の接地抵
抗をR2、鋼管１３と鉄筋１２ｃとの接触抵抗を
RP、壁１１の接地抵抗をR0とする。そして、電
流源１５から接地抵抗R1を介して大地へ矢印方
向に供給される電流をI1、大地から接地抵抗R2を
介して鋼管１３の反対側へ流入する電流をI2とす
ると、大地から接地抵抗R0を介して鉄筋１２ａ
へ流入する電流Ｉは（Ｉ＝I1−I2）となる。そし
て、電流I1に起因して鋼管１３の軸（Ｘ軸）廻り
に形成される磁界HYZは図示するように壁表面１
４に平行な面（Ｙ−Ｚ面）内に広がる。また、電
流（Ｉ＝I1−I2）に起因して鉄筋１２ｃの軸（Ｚ
軸）廻りに形成される磁界HXYは図示するように
壁表面１４に直交する面（Ｘ−Ｙ面）内に広が
る。したがつて、各磁気センサ１６ａ，１６ｂは
鋼管１３による磁界HYZを検出せずに鉄筋１２ｃ
による磁界HXYのみを検出することになる。 FIG. 2 is a perspective view for explaining the operating principle of the detection device of the embodiment. That is, in addition to vertical reinforcing bars 12a to 12e, horizontal reinforcing bars 20a to 20e are disposed within the wall 11, and the reinforcing bars 12 and 20 in both directions are arranged in a mesh shape. And now, if the steel pipe 13 is the central reinforcing bar 12c
Suppose that it is in electrical contact with Then, the voltage of the current source 15 is E, the ground resistance on the current source 15 side of the steel pipe 13 is R 1 , the ground resistance on the counter current source 15 side of the steel pipe 13 is R 2 , and the contact resistance between the steel pipe 13 and the reinforcing bar 12c is
R P and the ground resistance of the wall 11 are R 0 . Let I 1 be the current supplied from the current source 15 to the ground via the grounding resistor R 1 in the direction of the arrow, and I 2 be the current flowing from the ground to the opposite side of the steel pipe 13 via the grounding resistor R 2 . Reinforcement bar 12a from the ground via ground resistance R 0
The current I flowing into is (I=I 1 −I 2 ). The magnetic field H YZ formed around the axis (X-axis) of the steel pipe 13 due to the current I 1 is applied to the wall surface 1 as shown in the figure.
It spreads in a plane parallel to 4 (YZ plane). In addition, the axis ( Z
The magnetic field H Therefore, each magnetic sensor 16a, 16b does not detect the magnetic field H YZ due to the steel pipe 13 and
Only the magnetic field H XY due to this will be detected.
第２図における各電流の流れは第３図の等価回
路で表わすことが可能である。すなわち、この等
価回路において、鋼管１３の両側の接地抵抗R1，
R2が等しいとすると、簡単な考察により、鉄筋
１２ｃに流れる電流Ｉは(1)式で求まる。 The flow of each current in FIG. 2 can be represented by the equivalent circuit in FIG. 3. That is, in this equivalent circuit, the ground resistance R 1 on both sides of the steel pipe 13,
Assuming that R 2 is equal, the current I flowing through the reinforcing bar 12c can be found by equation (1) by simple consideration.
Ｉ＝I1−I2
＝Ｅ／｛２（RP＋R0）＋R1｝ …(1)
次にその電流Ｉが壁１１内を流れる様子を考察
する。すなわち、コンクリートの壁１１内には前
述したように複数の鉄筋１２ａ〜１２ｅ，２０ａ
〜２０ｅがメツシユ状に組まれている。しかし、
壁１１内に流れる総電流はそのメツシユが第４図
ａに示すように均一ならば、同図ｂに示すように
上下方向（Ｚ軸方向）に均一に流れる。したがつ
て、上下方向に延びるｎ本の鉄筋１２が存在すれ
ば各々の鉄筋に流れる電流ｉはＩ／ｎとなり、(2)
式で示される。I=I 1 −I 2 =E/{2(R P +R 0 )+R 1 } (1) Next, consider how the current I flows inside the wall 11. That is, within the concrete wall 11, as described above, there are a plurality of reinforcing bars 12a to 12e, 20a.
~20e are arranged in a mesh shape. but,
If the mesh is uniform as shown in FIG. 4a, the total current flowing in the wall 11 will flow uniformly in the vertical direction (Z-axis direction) as shown in FIG. 4b. Therefore, if there are n reinforcing bars 12 extending in the vertical direction, the current i flowing through each reinforcing bar is I/n, (2)
It is shown by the formula.
ｉ＝Ｅ／ｎ｛２（RP＋R0）＋R1｝ …(2)
次に１本の鉄筋１２ｃに流れる電流ｉによりこ
の鉄筋１２ｃ廻りに形成される磁界を求める。第
５図に示すようにこの電流ｉがＸ−Ｙ座標系の原
点（０、０）で紙面に対して垂直下向きに流れる
とすると、Ｐ点（ｘ、ｙ）における磁界HXYの大
きさは(3)式で示され、方向は時計方向である。i=E/n{2(R P +R 0 )+R 1 } (2) Next, the magnetic field formed around one reinforcing bar 12c by the current i flowing through this reinforcing bar 12c is determined. As shown in Figure 5, if this current i flows downward perpendicularly to the plane of the paper at the origin (0, 0) of the X-Y coordinate system, then the magnitude of the magnetic field H XY at point P (x, y) is It is shown by equation (3), and the direction is clockwise.
HX＝ｉ／2π√2＋2 …(3)
ここで鋼管１３に流れる電流I1により鋼管１３
の軸廻りに形成される磁界HYZの影響を無くして
鉄筋１２ｃの磁界HXYのみを検出するには、この
磁界HXYのＸ軸方向成分HXを測定すればよい。
すなわち、第５図から明らかなように、この磁界
HXは(4)式で示される。 H X = i/2π√ 2 + 2 …(3) Here, the steel pipe 13
In order to eliminate the influence of the magnetic field H YZ formed around the axis and detect only the magnetic field H XY of the reinforcing bar 12c, it is sufficient to measure the X-axis direction component H X of this magnetic field H XY .
In other words, as is clear from Figure 5, this magnetic field
H X is expressed by equation (4).
HX＝HXYcosθ
＝yi／2π（x2＋y2） …(4)
(4)式は壁１１内に鉄筋１２が１本だけ存在した
場合の値であるが実際には第２図に示すように壁
１１内には多数の鉄筋１２が配列されている。し
たがつて、(4)式を重ね合せる必要がある。 H X = H As shown, a large number of reinforcing bars 12 are arranged within the wall 11. Therefore, it is necessary to superimpose equation (4).
第６図は、壁１１の厚さ２ｄを12cm、各鉄筋１
２ａ〜１２ｅの相互間隔Ｓを10cm、本数ｎを５本
とし、各電流値ｉを0.3Aとした場合において、
１個の磁気センサを鉄筋１２ａの左方向位置から
鉄筋１２ｅの右方向位置へ移動させた場合の磁気
センサの出力特性図である。この特性図からも明
らかなように、磁気センサが各鉄筋１２ａ〜１２
ｅの中央位置（鉄筋１２ｃ）で磁界HXの極性が
反転する。したがつて、第６図の磁界特性が得ら
れれば鉄筋１２に電流が流れていることになり、
鋼管１３が壁１１内で鉄筋１２に電気的に接触し
ていることが検出される。 Figure 6 shows that the thickness 2d of the wall 11 is 12cm, and each reinforcing bar 1
When the mutual spacing S of 2a to 12e is 10 cm, the number n is 5, and each current value i is 0.3A,
It is an output characteristic diagram of a magnetic sensor when one magnetic sensor is moved from a position to the left of the reinforcing bar 12a to a position to the right of the reinforcing bar 12e. As is clear from this characteristic diagram, the magnetic sensor
The polarity of the magnetic field HX is reversed at the center position of e (reinforcing bar 12c). Therefore, if the magnetic field characteristics shown in Figure 6 are obtained, it means that current is flowing through the reinforcing bar 12.
It is detected that the steel pipe 13 is in electrical contact with the reinforcing bar 12 within the wall 11 .
しかしながら、実際には鋼管１３の接地抵抗
R1，R2の値は、この鋼管１３が鉄筋１２に接触
した場合の接触抵抗RPの値に比較して小さいた
めに、大地からこの接触部を介して鉄筋１２へ流
入する接地電流Ｉの値は非常に小さいので、地磁
気による磁界の影響を受けやすい。例えば電流源
１５の出力を調整して鋼管１３に流れる電流I1の
値を２Ａとしたとしても、複数の鉄筋１２ａ〜１
２ｅに同時に接地電流が流れるために、１本の鉄
筋１２に流れる電流ｉの値は数百ｍＡ程度とな
る。したがつて、例えば壁１１の厚さ２ｄを12cm
とした場合、この電流ｉによる壁表面１４におけ
る磁界HXの値は数十ｍＧ（ガウス）程度となり、
通常の地磁気による磁界の大きさ（0.7〜0.2ｍ
Ｇ）よりも小さくなる。 However, in reality, the ground resistance of the steel pipe 13
Since the values of R 1 and R 2 are small compared to the value of contact resistance R P when this steel pipe 13 contacts the reinforcing bars 12, the ground current I flowing from the ground to the reinforcing bars 12 through this contact portion Since the value of is very small, it is easily affected by the magnetic field caused by the earth's magnetism. For example, even if the output of the current source 15 is adjusted to set the value of the current I 1 flowing through the steel pipe 13 to 2A, the number of reinforcing bars 12a to 1
Since the ground current flows through 2e at the same time, the value of the current i flowing through one reinforcing bar 12 is approximately several hundred mA. Therefore, for example, the thickness 2d of the wall 11 is 12 cm.
In this case, the value of the magnetic field HX on the wall surface 14 due to this current i is approximately several tens of mG (Gauss),
Magnetic field size due to normal geomagnetism (0.7 to 0.2 m
G) will be smaller than.
このような地磁気の影響を排除するために第１
図に示すように一定間隔Ｌをあけて一対の磁気セ
ンサ１６ａ，１６ｂを配設している。そして、各
磁気センサ１６ａ，１６ｂで得られた各磁界の差
を差動増幅器１８で増幅するようにしている。そ
して、スペーサ１７で距離Ｌを固定したままＹ軸
方向に壁表面１４に沿つて移動させると、地磁気
を除いた各磁気センサ１６ａ，１６ｂ単体では第
６図に示した特性を距離ＬだけＹ軸方向に平行移
動した特性を描くので、地磁気がある場合でも差
動増幅器１８を用いることで、単体の二つの特性
の差を取るここと同じ値になり、第７図の特性図
になる。すなわち、鉄筋１２に電流が流れていな
い場所では各磁気センサ１６ａ，１６ｂで検出さ
れる各磁界は前述の地磁気による磁界のみである
ので等しい値となり、その差は非常に小さい値と
なる。しかし鉄筋１２に電流が流れている位置に
おいては各磁気センサ１６ａ，１６ｂで検出され
る磁界は第６図に示すようにＹ軸方向の位置によ
り大きく異なる。したがつて、その差は非常に大
きな値となる。したがつて、差動増幅器１８の出
力信号を記録計１９にて記録して第７図に示すよ
うに信号レベルに大きな変化が生じた位置を鋼管
１３が鉄筋１２に電気的に接触した位置であると
特定できる。 The first step is to eliminate the influence of geomagnetism.
As shown in the figure, a pair of magnetic sensors 16a and 16b are arranged at a constant interval L. A differential amplifier 18 amplifies the difference between the magnetic fields obtained by the magnetic sensors 16a and 16b. Then, if the distance L is fixed with the spacer 17 and it is moved along the Y-axis direction along the wall surface 14, each magnetic sensor 16a, 16b excluding the earth's magnetic field will have the characteristics shown in FIG. 6 along the Y-axis by the distance L. Since the characteristics are drawn parallel to the direction, even if there is earth's magnetism, by using the differential amplifier 18, the difference between the two characteristics of a single unit will be the same value as here, and the characteristic diagram shown in FIG. 7 will be obtained. That is, in a place where no current is flowing through the reinforcing bar 12, the magnetic fields detected by the magnetic sensors 16a and 16b are only the magnetic fields due to the earth's magnetism, so they have the same value, and the difference therebetween is a very small value. However, at the position where current is flowing through the reinforcing bar 12, the magnetic field detected by each magnetic sensor 16a, 16b differs greatly depending on the position in the Y-axis direction, as shown in FIG. Therefore, the difference is a very large value. Therefore, the output signal of the differential amplifier 18 is recorded by the recorder 19, and as shown in FIG. It can be determined that there is.
このように構成された鋼管の壁内金属接触検出
装置であれば、鋼管１３が壁１１内で鉄筋１２に
電気的に接触してこの鉄筋１２に流れる接地電流
Ｉによる磁界HXYの壁表面１４に直交する磁界
HXを検出するようにしているので、鋼管１３に
流れる電流I1に起因する磁界HYZの影響を排除で
き、鉄筋２に接地電流Ｉが流れたことを確実に検
出できる。 With the metal contact detection device in the wall of a steel pipe configured as described above, the steel pipe 13 electrically contacts the reinforcing bar 12 within the wall 11, and the magnetic field H magnetic field orthogonal to
Since H X is detected, the influence of the magnetic field H YZ caused by the current I 1 flowing through the steel pipe 13 can be eliminated, and it is possible to reliably detect that the ground current I flows through the reinforcing bar 2 .
さらに、相互に一定間隔Ｌを有した一対の磁気
センサ１６ａ，１６ｂを用いて前記鉄筋１２の接
地電流を検出するようにしているので地磁気の影
響を完全に排除した状態で測定できる。したがつ
て、鋼管１３が壁１１内で鉄筋１２に電気的に接
触していることを確実に検出できる。 Furthermore, since the ground current of the reinforcing bar 12 is detected using a pair of magnetic sensors 16a and 16b that are spaced apart from each other by a certain distance L, measurement can be performed while completely eliminating the influence of earth's magnetism. Therefore, it is possible to reliably detect that the steel pipe 13 is in electrical contact with the reinforcing bar 12 within the wall 11.
［発明の効果］
以上説明したように本発明によれば、鋼管が鉄
筋に電気的接触したときに鉄筋に流れる電流によ
つて形成される磁界を検出するようにしている。
したがつて、壁表面から非接触で簡単にかつ確実
に鋼管が鉄筋に接触したことを検出できる。ま
た、一対の磁気センサを用いることによつて地磁
気の影響を除去でき、測定精度の向上となり一層
信頼性を向上できる。[Effects of the Invention] As explained above, according to the present invention, when a steel pipe comes into electrical contact with a reinforcing bar, the magnetic field formed by the current flowing through the reinforcing bar is detected.
Therefore, contact of the steel pipe with the reinforcing bar can be easily and reliably detected without contacting the wall surface. Furthermore, by using a pair of magnetic sensors, the influence of earth's magnetism can be removed, measurement accuracy can be improved, and reliability can be further improved.
第１図は本発明の一実施例に係わる鋼管の壁内
金属接触検出装置の概略構成を示す模式図、第２
図は同実施例の動作原理を説明するための透視
図、第３図は同動作原理を説明するための等価回
路図、第４図は同実施例の鉄筋における電流の流
れを示す図、第５図は同電流で形成される磁界を
示す図、第６図および第７図は同実施例の磁界特
性図、第８図および第９図は従来の鋼管の壁内金
属接触検出方法を示す図である。
１１……壁、１２，２０……鉄筋、１３……鋼
管、１４……壁表面、１５……電流源、１６ａ，
１６ｂ……磁気センサ、１７……スペーサ、１８
……差動増幅器、１９……記録計。
FIG. 1 is a schematic diagram showing the general configuration of a metal contact detection device in the wall of a steel pipe according to an embodiment of the present invention, and FIG.
The figure is a perspective view for explaining the operating principle of the same embodiment, FIG. 3 is an equivalent circuit diagram for explaining the operating principle, FIG. 4 is a diagram showing the flow of current in the reinforcing bars of the embodiment, Figure 5 shows the magnetic field formed by the same current, Figures 6 and 7 show the magnetic field characteristics of the same example, and Figures 8 and 9 show the conventional method for detecting metal contact within the wall of a steel pipe. It is a diagram. 11... Wall, 12, 20... Rebar, 13... Steel pipe, 14... Wall surface, 15... Current source, 16a,
16b...Magnetic sensor, 17...Spacer, 18
... Differential amplifier, 19 ... Recorder.
Claims (1)
直角に貫通する鋼管が前記鉄筋と電気的接触して
いることを検出する鋼管の壁内金属接触検出装置
において、前記鋼管と大地間に設けられ、前記壁
を貫通する前記鋼管を電流帰路として大地を電流
往路とする電流回路を形成する電流源と、それぞ
れ前記壁面に直交する磁界を検出するとともに互
いに一定の位置関係を保持しながら前記壁面に沿
つて移動制御される一対の磁気センサと、これ等
一対の磁気センサにて検出された各磁界の差を増
幅する差動増幅器と、この差動増幅器の出力信号
を記録する記録計とを備えたことを特徴とする鋼
管の壁内金属接触検出装置。1. In a metal contact detection device in a steel pipe wall that detects that a steel pipe that penetrates a wall of a building containing reinforcing bars at a substantially right angle to the wall surface is in electrical contact with the reinforcing bars, a device installed between the steel pipe and the ground. a current source that forms a current circuit with the steel pipe penetrating the wall as a current return path and the earth as a current outgoing path; A pair of magnetic sensors whose movement is controlled along A metal contact detection device in the wall of a steel pipe, characterized by comprising:
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP60178724A JPS6238370A (en) | 1985-08-14 | 1985-08-14 | Contact detecting device for metal inside wall of steel pipe |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP60178724A JPS6238370A (en) | 1985-08-14 | 1985-08-14 | Contact detecting device for metal inside wall of steel pipe |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6238370A JPS6238370A (en) | 1987-02-19 |
| JPH0516550B2 true JPH0516550B2 (en) | 1993-03-04 |
Family
ID=16053459
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP60178724A Granted JPS6238370A (en) | 1985-08-14 | 1985-08-14 | Contact detecting device for metal inside wall of steel pipe |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6238370A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH01314990A (en) * | 1988-06-15 | 1989-12-20 | Tokyo Gas Co Ltd | Contact detection method and apparatus for electroconductive object of underground buried tube |
-
1985
- 1985-08-14 JP JP60178724A patent/JPS6238370A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6238370A (en) | 1987-02-19 |
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