JPH05187851A - Method and instrument for measuring length of buried pipeline - Google Patents

Abstract

PURPOSE:To obtain a method by which the length of a pipeline buried in the ground can be measured with high accuracy without digging the ground over the full length of the pipeline irrespective of the buried direction and material of the pipeline. CONSTITUTION:White noise generated from a white noise generator 11 is transmitted into a branch buried pipe 16 from a loudspeaker 12. The noise propagated through the pipe 16 is caught by means of microphones 13 and 14 installed to two points and the length of the pipe 16 is measured by calculating the cross-correlative function between the caught noise signals by means of a correlator 15. By measuring the lengths of the branch pipe 16 to be measured and branch buried pipes 17 and 19 adjacent to the pipe 16, the length of the pipe 16 is measured from the measured results.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used for a buried pipe length measuring method and a method therefor capable of highly accurately measuring the length of a pipe such as a gas pipe or a water pipe buried underground. The present invention relates to a length measuring device.

[0002]

2. Description of the Related Art Conventionally, as a method for measuring the length of a pipeline such as a gas pipe or a water pipe buried in the ground without excavating,
A method of using a buried metal tube detector utilizing electromagnetic induction is known. This method is to measure the length of a buried pipe by detecting a position of the buried pipe by capturing a magnetic field generated along the pipe on the surface of the earth by applying a minute alternating current to the target buried pipe. is there.

[0003]

In this method, since the position of the buried pipe is detected in a form projected on the surface of the earth, the pipe length in the horizontal direction can be measured, but the pipe length in the vertical direction is measured. It is not possible. Further, when the buried pipe is made of a non-conductive material, an alternating current cannot flow through the buried pipe in the first place, and the pipe length cannot be measured.

The present invention has been made in view of the above problems, and an object of the present invention is to measure the pipe length with high accuracy regardless of the burying direction of the buried pipe and the material thereof. To do.

[0005]

In order to achieve the above object, the first aspect of the present invention is to convert white noise into sound and emit the sound into a pipe, and to emit sound propagating in the pipe at two different points. The method of measuring the pipe length by capturing the sound and calculating the cross-correlation coefficient of acoustics at these two points was carried out in the target buried pipe and the adjacent buried pipes on both sides. It is intended to provide a method for measuring the length of a buried pipeline which measures the length of the target buried pipeline from the measurement result.

The method for measuring the length of a buried pipeline according to the present invention is based on the following principle.

As shown in FIG. 1, assuming that the buried branch pipe 1 to be measured and the buried branch pipes 2 and 3 on both sides thereof are connected to the buried main pipe 4, the lengths of the buried branch pipes 1, 2 and 3 are determined. Let l ₁ , l ₂ and l ₃ , respectively, and the length of the buried main pipe 4 between the connection points of the buried branch pipes 1, ₂ and ₃ be L ₁ and L ₂ , respectively.

Assuming that the length of the conduit consisting of the buried branch pipes 1 and 2 and the buried main pipe 4 is A, A = l ₁ + l ₂ + L ₁ (1) Similarly, the buried branch pipes 1 and 3 and the buried main pipe 4 Let B be the length of the pipeline consisting of and B be the length of the pipeline consisting of the buried branch pipes 2 and 3 and the buried main pipe 4, and B = l ₁ + l ₃ + L ₂ (2) C = 1 ₂ +1 ₃ + L ₁ + L ₂ (3) Therefore, the length l ₁ of the buried branch pipe 1 is calculated by the above equations (1), (2),
From (3), it can be calculated that l ₁ = (A + BC) / 2 (4).

As shown in FIG. 2, a white noise is emitted from the speaker 5 into the pipe line 6, and the sensor is arranged at two points.
Suppose this sound is captured at 7 and 8. Acoustic sensor-7
, T ₁ hours later, and the sensor-8 t ₂ hours later. If the time difference is Δt and the sound velocity in the pipeline is V,
The conduit length l between the sensor-7 and the sensor-8 is l = V · Δt (5). The sound velocity V in the pipeline 6 is: V = 331.45 (1 + T / 273) ^1/2 (6) where T is the temperature in the pipeline 6. Transmission time difference Δt
Can be obtained by calculating the cross-correlation coefficient of the two acoustic signals captured by the sensor-7 and the sensor-8. If the two signals are f (t) and g (t), the cross-correlation coefficient R (τ) is

[0010]

[Equation 1]

Here, if f (t) = g (t-t '), R (τ) becomes maximum at τ = t', and f (t) and g
If (t) is a completely independent signal, then R (τ) = 0.

From the above equations (1) to (7), the length l ₁ of the target buried branch pipe 1 can be obtained.

In order to carry out the above-mentioned method for measuring the length of the buried pipeline, the second aspect of the present invention is to provide a white noise generator and a spin filter which converts the generated white noise signal into sound and emits it into the pipeline. (EN) Provided is a buried pipe length measuring device comprising a car, two microphones for capturing sound propagating in a pipeline, and a correlator for calculating a cross-correlation coefficient of the captured two sound. is there.

[0014]

Embodiments of the present invention will be described with reference to the drawings. As shown in FIG. 3, the buried pipe length measuring device of the present invention comprises a white noise generator 11, a speaker 12, two microphones 13 and 14, and a correlator 15.

The white noise generator 11 has a frequency band of 100H.
The white noise of z to 5 kHz is generated, and the speaker 12 converts this white noise into sound and the buried branch pipe 1
It is discharged into the inside of the pipe 6, and is arranged at the tip of the buried branch pipe 16.

The microphones 13 and 14 capture the sound propagating in the conduit, and the microphone 13 is arranged near the tip of the buried branch pipe 16,
Is arranged at the tip of the adjacent buried branch pipe 17.

The correlator 15 calculates the cross-correlation coefficient from the acoustic signals captured by the two microphones 13 and 14 to obtain the acoustic transmission time difference Δt.

Next, the operation of the length measuring device for the buried pipeline and the method for measuring the length of the buried pipeline will be described.

As shown in FIG. 3, white noise is generated by the white noise generator 11, and sound is emitted from the speaker 12 at the tip of the embedded branch pipe 16 to be measured.

The emitted sound propagates through the buried branch pipe 16, the buried main pipe 18, and the buried branch pipe 17, and a part of the sound propagates through the buried branch pipe 1.
6 is captured by the microphone 13 disposed near the tip of the buried reference pipe 6, and a part thereof is captured by the microphone 14 disposed at the tip of the buried branch pipe 17.

The sound captured by the microphones 13 and 14 is converted into an electric signal and input to the correlator 15. Then, the correlator 15 calculates the cross-correlation coefficient of these two acoustic signals.

The cross-correlation coefficient in this case is given as the sound transmission time difference Δt, and by substituting this into the above equation (5), the embedded main pipe 18 from the tip of the embedded branch pipe 16 to be measured is measured. The conduit length A up to the tip of the adjacent buried branch pipe 17 is calculated via the.

Similarly, the pipe length B from the tip of the buried branch pipe 16 to be measured to the tip of the adjacent buried branch pipe 19 (not shown) via the buried main pipe 18,
The pipe length C from the tip of the adjacent buried branch pipe 17 to the tip of the adjacent buried branch pipe 19 via the buried main pipe 18 is calculated, and these are substituted into the above formula (4) to obtain the buried branch pipe 16 it is to calculate the pipe length l _1.

Next, a more concrete description will be given based on the result of actually measuring the pipeline length by carrying out the method for measuring a buried pipeline according to the present invention.

Example 1 A pipe line as shown in FIG. 4 was constructed. Buried branch pipes P ₁ , P ₂ and P ₃ each have a pipe diameter of 25.
A, the pipe length was 8.55 m, and the buried main pipe P ₀ had a pipe diameter of 50 A. Spin at the distal end of the buried branch pipe P ₁ - Ca - a conduit length l ₁ of the buried branch pipe P ₁ by emitting white noise was measured from. The measurement results are as shown in Table 1.

[0026]

[Table 1]

As shown in FIGS. 7 to 9, there is a clear peak in the correlation diagram, and the buried branch pipe P ₁ obtained from this is shown.
It was found that the measured value of the pipe line length l ₁ of was 8.50 m, and the error from the actual value was only 0.05 m, and that the length measurement with extremely high accuracy was possible.

(Comparative Example 1) Instead of emitting white noise from the speaker, noise was generated by rubbing the tube wall with the tip of the driver, and the others were buried under the same conditions as in (Example 1). the pipe length l ₁ of the branch pipe P ₁ was measured. The measurement results are as shown in Table 1.

As shown in FIGS. 10 to 12, a plurality of peaks are generated in the correlation diagrams, but the measured value of the conduit length l ₁ of the buried branch pipe P ₁ obtained from the maximum peak is 8.795 m. However, the error from the actual value was 0.245 m, and the measurement error was large as compared with (Example 1).

Example 2 A pipe line as shown in FIG. 5 was constructed. Buried branch pipes P ₄ , P ₅ , and P ₆ each have a pipe diameter of 25.
A, the pipe length was 16.55 m, and the buried main pipe P ₀ had a pipe diameter of 50 A. At the tip of the buried branch pipe P ₄ , a spin
Ca - from pipe length buried branch pipe P ₄ to emit white noise l ₄
Was measured. The measurement results are as shown in Table 1.

As shown in FIGS. 13 to 15, in the correlation diagrams, the waveform is more disturbed than in the first embodiment, but the maximum peak
The measured value of the line length l ₄ of the buried branch pipe P ₄ obtained from
Although it was 6.32 m and the error from the actual value was 0.23 m, it was found that the length measurement with sufficient accuracy in practical use was possible.

(Comparative Example 2) Instead of emitting white noise from the speaker, noise was generated by rubbing the tube wall with the tip of the driver, and the others were buried under the same conditions as (Example 2). the pipe length l ₄ of the branch pipe P ₄ were measured. The measurement results are as shown in Table 1.

As shown in FIG. 16, since the waveform is disturbed in the correlation diagram and the maximum peak is not clearly indicated, the measured value of the conduit length l ₄ of the buried branch pipe P ₄ could not be calculated. ..

Example 3 A pipe line as shown in FIG. 6 was constructed. Buried branch pipes P ₇ , P ₈ and P ₉ each have a pipe diameter of 25.
A, the pipe length was 16.55 m, and the buried main pipe P ₀ had a pipe diameter of 50 A. At the tip of the buried branch pipe P ₇ ,
White noise is emitted from the car and the line length of the buried branch pipe P ₇ is l ₇
Was measured. The measurement results are as shown in Table 1.

As shown in FIGS. 17 to 19, in the correlation diagrams, the waveform is more disturbed than in the first embodiment, but the maximum peak
The measured value of the line length l ₇ of the buried branch pipe P ₇ obtained from
It was 6.89 m, and the error from the actual value was 0.34 m, but it was found that the measurement can be performed with sufficient accuracy in practical use.

(Comparative Example 3) Instead of emitting white noise from the speaker, noise was generated by rubbing the tube wall with the tip of the driver, and the others were buried under the same conditions as in (Example 3). the pipe length l ₇ of branch pipes P ₇ was measured. The measurement results are as shown in Table 1.

As shown in FIG. 20, a plurality of peaks are generated in the correlation diagram, and the maximum peak is not clearly indicated. Therefore, it is possible to calculate the measured value of the conduit length l ₇ of the buried branch pipe P _7. could not.

In the above measurement results, the measured value is slightly larger than the actual value because the pipe having a length of 4 mm is connected by the socket or the elbow, so that the pipe length becomes longer by this amount. Conceivable. In the former case, the correlation waveform is more disturbed when the noise is generated by rubbing the tube wall with the tip of the driver, as compared with the case where white noise is emitted from the speaker. Most of the sound propagates in the pipe, but in the latter case, it is considered that the sound propagates in the pipe and the wall of the pipe. Furthermore, it is considered that the plurality of peaks are generated in the correlation waveform because the sound is reflected at the bent portion of the conduit.

[0039]

According to the method for measuring the length of the buried pipeline of the present invention, the sound due to the white noise is propagated in the pipeline, the sound is captured at two points, and the propagation time difference is obtained by the cross-correlation coefficient. Since the pipeline length is calculated, the pipeline length can be measured with high accuracy regardless of the burying direction of the buried pipe and the material thereof.

According to the buried pipe length measuring apparatus of the present invention, this length measuring method can be effectively implemented.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an arrangement of a buried branch pipe and a buried main pipe.

FIG. 2 is an explanatory diagram showing a principle of measuring a conduit length.

FIG. 3 is an explanatory diagram showing an installed state of a length measuring device for a buried pipeline according to the present invention.

FIG. 4 is a structural example of a buried pipeline.

FIG. 5 is a configuration example of a buried pipeline.

FIG. 6 is a structural example of a buried pipeline.

FIG. 7 is a correlation waveform diagram of an acoustic signal.

FIG. 8 is a correlation waveform diagram of an acoustic signal.

FIG. 9 is a correlation waveform diagram of an acoustic signal.

FIG. 10 is a correlation waveform diagram of an acoustic signal.

FIG. 11 is a correlation waveform diagram of an acoustic signal.

FIG. 12 is a correlation waveform diagram of an acoustic signal.

FIG. 13 is a correlation waveform diagram of an acoustic signal.

FIG. 14 is a correlation waveform diagram of an acoustic signal.

FIG. 15 is a correlation waveform diagram of an acoustic signal.

FIG. 16 is a correlation waveform diagram of an acoustic signal.

FIG. 17 is a correlation waveform diagram of an acoustic signal.

FIG. 18 is a correlation waveform diagram of an acoustic signal.

FIG. 19 is a correlation waveform diagram of an acoustic signal.

FIG. 20 is a correlation waveform diagram of an acoustic signal.

[Explanation of symbols]

 11 White Noise Generator 12 Speaker 13 Microphone 14 Microphone 15 Correlator 16 Buried branch pipe 17 Buried branch pipe 18 Buried main pipe 19 Buried branch pipe

Claims (2)

[Claims] 1. The white noise is converted into sound and emitted into the pipe, and the sound propagating in the pipe is captured at two different points,
The method of measuring the pipeline length by calculating the cross-correlation coefficient of the acoustics at these two points was carried out in the target buried pipeline and the buried pipelines on both sides adjacent to it, and A method for measuring the length of a buried pipeline, which comprises measuring the length of the buried pipeline. 2. A white noise generator, a speaker that converts the generated white noise signal into sound and emits the sound into a pipe, and two microphones that capture the sound propagating in the pipe.
A buried pipe length measuring device comprising a correlator that calculates a cross-correlation coefficient of two captured sounds.