JPS6193973A - Position detecting method of buried pipe underground - Google Patents

Abstract

PURPOSE:To detect with high accuracy the position and depth of a buried substance with good operability by detecting a buried substance with magnetic sensors at plural points on the ground surface and by performing an arithmetic processing based on the distance, magnetic field direction, etc. among plural points. CONSTITUTION:An induction magnetic field 2 is generated from a pipe 1 when an electromagnetic wave is transmitted from a transmitter to the buried pipe 1 underground. This magnetic field 2 is detected by the magnetic sensors at the known points A-D, etc. on the ground surface and the depth D of the buried pipe 1 and the position M1 with a point A as the reference, etc. are decided by the arithmetic processing of the equation I, II based on the direction theta1-theta3, etc. of the detected magnetic field H1-H3, etc. and the position and depth of the buried substance is detected with high accuracy and good operability. L1: distance between points A, B in the equation.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a method for detecting the position of underground pipes, and in particular, detects the position of buried objects such as gas pipes, water pipes, oil pipes, etc. from the ground surface to improve maintainability. The present invention relates to a method for detecting the position of underground pipes suitable for improving the performance of underground pipes.

[Background of the invention]

Generally, as a buried position detection method, Japanese Patent Application Laid-Open No. 57-2008
As described in Publication No. 02, a return current line is wired on the ground surface to form a rectangular closed loop with the buried conductor and the line as opposing sides, and the combined magnetic field of the magnetic field due to the conductor and the magnetic field due to the line is A method is known in which the direction is measured at two points on the ground surface and measured by changing the layout of the tracks. This method requires a return current line, and the return current line must be arranged approximately parallel to the buried conductor.

[Purpose of the invention]

An object of the present invention is to provide a method for detecting the position of underground pipes with high accuracy and good workability.

[Summary of the invention]

The present invention relates to an electromagnetic induction method, but as shown in a conventional example in FIG.
3 is made into a closed loop circuit with the branch pipe 11, lead wire 12, transmitter 14, etc., and the return current line 13 is rectangular in shape and is approximately parallel to the buried pipe 1. However, the present invention detects the direction of the induced magnetic field from the buried pipe at at least two points on the earth's surface, and measures the distance between the two points and the direction of the magnetic field (inclination relative to the reference axis). This method calculates the position of a buried pipe from the angle), and unlike the conventional example described above, a rectangular closed loop and composite magnetic field are not required, and the position can be detected with high accuracy by applying the direction of the magnetic field from the buried pipe. This is what I did.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIG. 1st
As shown in the figure, a buried pipe 1 is buried at a depth D right below a point 0, with the ground surface G as the X axis and the depth direction from the ground surface G as the Y axis. Point A-0 is each position of the magnetic detection sensor, and point A and point B are Ll.

It is located at a distance between point B and point C HL2. Magnetic field size H at point A
Set the angle indicating + and direction to 01. Hereinafter, point B and point C are H2, θ2, and H3, respectively.

Let it be θ3. The induced magnetic field 2 generated from the buried pipe 1 is inversely proportional to the distance from the buried pipe 1, and is arranged in the same circular shape with the buried pipe in the center. The depth D of the buried pipe is determined from point A and point B using the following formula.

It can be found in the same way from point B and point 0. Furthermore, the position of the buried pipe 1 is M1=Dtallθ1(8) based on point A, and M2=Dtanθ2(4) at point B. The more accurate the detection data, the better, but at least 2
Let the data between points be a pair, and as an example, equation (1) and (
2) The accuracy is improved by taking the average value of equation (3) and equation (4). In Figure 1, it is not limited to only 3 points A to C, but 4 or more points should be used to improve accuracy.
, Fig. 2 shows that an electromagnetic field is generated from a transmitter 4 placed on the ground surface, a secondary current is passed through a buried pipe 1, and an induced magnetic field 2 is induced by this secondary current.
This is an example in which side-to-side comparison is performed using a magnetic sensor 3, a detector placed on the G plane above the earth's surface. A to C indicating the position of the magnetic sensor 3
is the same as in FIG.

In Fig. 1, the distances LL and L2 between the magnetic sensors and the angle θ1.
θ Snow etc. can be processed by an arithmetic circuit and the position 0 on the buried pipe and the buried depth Dt- can be determined, and the workability is very good.

FIG. 3 shows an embodiment of a position detection method in which a circuit of a transmitter 4 on the ground surface is connected to a branch pipe 5 of a buried pipe 1.

FIG. 4 shows the relationship between the horizontal axis and the position of the magnetic sensor with reference to the zero point in FIG. 2, and the vertical axis and the angle of the magnetic field at each position. α on the horizontal axis is a multiple of D when the depth D of the buried pipe is 1.

When α exceeds 3, θ does not show a large change. Figure 5 shows the relationship between the horizontal axis in Figure 1, the position of the magnetic sensor centered on the 0 point in Figure 2 (same as Figure 4), and the vertical axis in relation to the magnitude of the magnetic field at each position. The magnitude of the magnetic field at the 0 point on the buried pipe of size D was set to 1. From FIGS. 4 and 5, the optimum detection position for θ and H is preferably in the range of α from about 0.5 to 2.

〔Effect of the invention〕

According to the present invention, in the method of determining the buried position by detecting the magnetic field induced by underground pipes, it is possible to determine the buried position based on the direction of the magnetic field and the position of each detection point, and the workability is good and the effect of high precision measurement is achieved. be.

[Brief explanation of drawings]

Figure 1 is a detailed explanatory diagram of the present invention, Figures 2 and 3 are measurement schematic diagrams, Figure 4 is a characteristic diagram showing the relationship between the position of the magnetic sensor and the detection angle (θ) of the sensor, and Figure 5. 6 is a characteristic diagram showing the relationship between the position of the magnetic sensor and the magnitude of the detected magnetic field, and FIG. 6 is a principle diagram of a conventional measuring circuit. 1... Buried pipe, 2... Induced magnetic field, 3... Detector (
magnetic sensor), 4... transmitter, 5... branch pipe, 1
DESCRIPTION OF SYMBOLS 1... Branch pipe, 12... Lead wire, 13... Return current line, 14... Transmitter. Second edict

Claims (1)

[Claims] 1. A magnetic sensor that detects the strength and direction of a magnetic field, a position detection sensor that detects the position of the magnetic sensor, and a data processing circuit that processes detection data of each of the sensors;
It consists of a display device that displays the calculation results of the data processing circuit, and a transmitter that transmits electromagnetic waves to the underground pipe, and detects the induced magnetic field from the underground pipe at at least two points on the ground surface. A method for detecting the position of an underground pipe, characterized in that the position and depth of the underground pipe are detected from the distance between them and the direction of the magnetic field at each position, that is, the inclination angle with respect to a reference coordinate axis.