JPH0545920B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a method for detecting the position of a buried object, and in particular, detects the approximate position of the buried object during excavation near the buried object, and detects damage caused by digging tools to the buried object. The present invention relates to a buried object position detection method suitable for preventing.

[Background of the invention]

Conventional methods for detecting buried objects include, for example,
As shown in Japanese Patent No. 49327, a method of inserting current poles into the soil to form a current circuit and detecting changes in the current has been studied.
However, with this method, 1. It is almost impossible to detect buried objects that have a coating, such as ordinary buried pipelines, unless the coating is destroyed and the object comes into direct contact with the buried object.

2 In water rich soil, the influence of moisture is large and it is difficult to obtain effective detection sensitivity.

There were other drawbacks.

Furthermore, as described in Japanese Patent Publication No. 34-42, there is also known a method of measuring the position of an object to be detected based on the strength of magnetic flux passing through a magnetic path formed by the object.

However, this method has the disadvantage that it is not reliable enough to measure changes in distance to objects that are buried, as only a single change can be measured.

[Object of the Invention] The present invention has been made in view of the above-mentioned points, and its purpose is to prevent buried objects with coatings and objects buried in the soil with high electrical conductivity. To provide a buried object position detection method capable of detecting the position of a buried object without coating or damaging the surface of the buried object.

[Summary of the invention]

As mentioned above, the conventional method of detecting current (electrical resistance) using current electrodes is difficult to detect when there is an insulating layer on the surface of the buried object, or even if there is no insulating layer, when there is a lot of moisture in the soil near the buried object. It has been found that it has little effect. This method was studied to see if there was an effective method in place of the above method.

That is, for this reason, in the present invention, an insertion pole inserted near a buried object buried underground;
An excavating tool for excavating underground, a component forming at least one of a magnetic path and an electric path connecting these insertion poles and the excavating tool, a power source and a current detector provided in the middle of this component, An insertion pole and at least one of an electromagnetic pole and a dielectric electrode installed at the tip of the underground side of the excavation tool are provided, and when the insertion pole is inserted into the ground and the excavation with the excavation tool progresses, a part of the buried object is removed. An electromagnetic path is formed by an insertion pole, a structure, and the excavation tool, and as the excavation tool approaches the buried object, a magnetic flux change appears in the structure forming the magnetic path, and a structure forming the electric path. The position of the buried object is detected by detecting the induced current flowing through the buried object and the change in phase angle using the current detector.

[Embodiments of the invention]

The present invention will be described below based on embodiments shown in the drawings.

FIG. 1 shows an embodiment of the present invention.

In the figure, 1 is a buried pipe buried underground, and a coating 2 is applied to the surface of this buried pipe 1. Reference numeral 3 denotes an insertion pole, which is magnetically connected to the excavator 5 via a magnetic path component 4. A power source 6 and a current detector 7 are provided in the middle of the magnetic path structure 4.

In the above configuration, the insertion pole 3 and the excavation tool 5 themselves are configured as magnetic poles, but apart from this method, as shown in FIG. An induction pole 13 may be provided, or a second
As shown in FIG. b, an electromagnetic pole 14 having an excitation coil 15 may be provided at the tip of the excavator 5 on the underground side. Note that 12 is a cutting blade for excavating the ground.

In this case, the dielectric electrode 13 and the electromagnetic pole 14 are connected via the conductive wire 16 as shown by the dotted line in FIG.
It is connected to an interelectrode electric wire 8 that connects the insertion pole 3 and the excavation tool 5. A power source 6 and a current detector 7 are provided in the middle of the interelectrode conductive wire 8.

Note that when the dielectric electrode 13 is provided at the underground tip of the excavating tool 5, a dielectric electrode is also provided at the underground tip of the insertion pole 3; When the electromagnetic pole 14 is provided, the electromagnetic pole is provided at the tip of the insertion pole 3 on the underground side.

Here, since the planar position and approximate depth of the buried pipe 1 are known in advance from the construction drawings at the time of burying,
According to this construction drawing, the insertion pole 3 is inserted approximately in the vicinity of the buried pipe 1, and then excavation with the excavation tool 5 is started.

Then, the excavation with the excavator 5 progresses, and the buried pipe 1
a part of the insertion pole 3, the magnetic path component 4, the excavation tool 5,
Alternatively, if a part of the buried pipe 1, the insertion pole 3, the inter-electrode conductive wire 8, and the excavation tool 5 form an electromagnetic path, and the insertion pole 3 and the excavation tool 5 are formed by the electromagnetic pole 14, the magnetic flux changes. In addition, when the insertion electrode 3 and the excavation tool 5 are formed of a dielectric electrode 13, the position of the buried pipe 1 is detected by detecting changes in the dielectric current and phase angle, respectively.

That is, as shown by the solid line in FIG. 1, when the insertion pole 3 and the excavator 5 themselves are magnetic poles, the magnetic flux 9 passing through the insertion pole 3, the magnetic path component 4, and the excavator 5 is constant. At this time, the current flowing from the power source 6 and detected by the current detector 7 changes as shown as an exciting current (i.e., magnetic flux) 21 in FIG. .
This also applies to the case where the electromagnetic pole 14 shown in FIG. 2b is used.

On the other hand, when the dielectric electrode 13 shown in FIG. 2a is provided, the current flowing from the power source 6 and its phase angle (tan δ) are
The phase angle 22 and the induced current 23 change as shown in the figure.

The present invention attempts to detect the distance between a buried object and an excavating tool through the above-described changes in current or changes in dielectric loss coefficient (or phase angle). Figure 1,
If the current or dielectric loss coefficient (or phase angle) is set as a threshold value at the position h ₀ as shown in Figure 3, the distance can be estimated without damaging the buried object by tracking these changes. I can do it. In this case, magnetic flux and dielectric properties are used, so there is no possibility of undetectability due to coating of buried objects or moisture.

As described above, according to the present invention, it is possible to detect the position of a buried object without being significantly affected by the presence or absence of coating of the buried object and the amount of moisture in the soil, unlike the resistance method. It can be expected to have great effects as a system device to prevent damage to buried objects when excavating near objects. To prove the above, we will show the problems of the resistance method and the characteristics of the magnetic flux method as an example.

The current in Japanese Patent Application Laid-Open No. 53-49327 is exactly as follows.

That is, I=I ₁ +I ₂ =E/R ₅ +R ₁ +R ₀ +E/R ₅ +R ₆ ′+R ₀ ……(1
) These constants are the same as above. however,
R ₆ ′ is the sum of the resistance of the coating and the resistance between the coating and the drilling electrode. In this case, as is obvious, for example, if there is a coating, R ₀ / R ₆ ' / R ₅ /
R ₆ ′0 and I≒I ₁ (I ₂ 0) …(2) Therefore, unless the coating is damaged and R ₆ ′ is relatively close to R ₀ and R ₅ , I ₂ /I ₁ It is difficult to determine the value.

On the other hand, in the case of the magnetic pole according to the present invention, φ・h'=KI I=1/K・φ・h'...(3) I is the current in Figure 17, φ is the magnetic flux in Figure 19, K is a constant, h ' is the equivalent distance from the buried pipe, and if φ, that is, d/dtφ=E=const, it can be easily detected because it changes approximately in proportion to h'.

〔Effect of the invention〕

According to the buried object position detection device of the present invention described above, even for buried objects with coatings and buried objects buried in soil with high electrical conductivity, it is possible to damage the coating and the surface of buried objects. It is very effective because it allows you to detect the location of buried objects without having to worry about it.

[Brief explanation of drawings]

Figure 1 is a principle diagram showing an embodiment of the buried object position detection method of the present invention, Figures 2a and b are diagrams showing an example in which an electromagnetic pole is provided on the excavation tool of Figure 1, and Figure 3 is an electromagnetic Current, inductive loss coefficient, relative to the distance of the pole from the buried object,
FIG. 3 is a characteristic diagram showing phase angle and phase angle. 1... Buried pipe, 2... Coating, 3... Insertion pole,
4...Magnetic path component, 5...Drilling tool, 6...Power source,
7...Current detector, 8...Inter-electrode conductive wire, 9...
Magnetic flux, 10... Connection device, 11... Ground, 12...
...cutting blade, 13...dielectric electrode, 14...magnetic pole, 15...
... Excitation coil, 16 ... Conductive wire, 21 ... Excitation current, 22 ... Phase angle, 23 ... Dielectric current.

Claims (1)

[Claims] 1. An insertion pole that is inserted near a buried object buried underground, an excavation tool that excavates underground, and a component that forms at least one of a magnetic path and an electric path that connect these insertion poles and the excavation tool. and a power source and a current detector provided in the middle of the structure, and at least one of an electromagnetic pole and a dielectric electrode installed at the tip of the insertion pole and the underground side of the excavation tool, After being inserted into the ground, excavation by the excavation tool progresses, and a part of the buried object, the insertion pole, the structure, and the excavation tool form an electromagnetic path, and as the excavation tool approaches the buried object, the The position of the buried object is detected by detecting changes in magnetic flux appearing in a component forming a magnetic path, changes in an induced current flowing in a component forming an electric path, and a phase angle using the current detector. A method for detecting the location of buried objects.