JPS60238708A - Detecting method of thickness of underground buried pipe - Google Patents

Abstract

PURPOSE:To detect easily and exactly a thickness of a buried pipe on the ground surface by a simple operation, by executing an ultrasonic excitation to the buried pipe by an ultrasonic sound source provided on a branch pipe exposed to the ground surface, and detecting its reflected ultrasonic wave by an ultrasonic wave receiver on the ground surface. CONSTITUTION:A vibrator 6 which is driven by a vibrator driving device 7 and executes an ultrasonic excitation to a buried water pipe under the ground 2 is installed to the outside peripheral surface, etc. of a branch pipe 3. Also, an ultrasonic microphone 9 for receiving a feeble ultrasonic wave transferred through under the ground 2 from the water pipe 1 is provided so as to be movable adjacently or closely on the ground surface. Also, this system is provided with a synchronizing signal detector 8 for processing a signal by making its detecting signal synchronize with an exciting signal of the vibrator driving device 7, extracting a signal component containing an amplitude component signal and a phase component signal, and eliminating a noise. In this way, the handling operation is executed easily, and a thickness of the underground buried pipe can be detected easily and exactly.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical field to which the invention pertains] The present invention relates to an underground pipe thickness detection method that can detect the thickness of underground pipes such as water pipes and gas pipes buried underground.

[Prior art and its problems]

Generally, when expanding or replacing underground pipes, if you can know the thickness of the underground pipe in advance, you can prepare a new underground pipe or replacement pipe that matches that thickness, and therefore the construction work can be carried out. You can expect to eliminate wasted time and improve work efficiency. Therefore, various detection methods have been proposed that can easily detect the thickness of underground pipes on the ground surface, but each detection method has various problems that need to be solved, and is not sufficient for practical use. It wasn't satisfying.

[Purpose of the invention]

The present invention has been made in view of the above points, and is based on the conventional technique 44i.
To provide an underground pipe thickness detection method that can effectively solve the above problems, easily and reliably detect the thickness of an underground pipe on the ground surface, and is easy to handle.

[Key points of the invention]

In order to achieve such an object, the present invention uses an ultrasonic sound source installed in a branch pipe that is branched from a buried pipe buried underground and exposed to the surface of the earth to excite the buried pipe with ultrasonic waves. The ultrasonic waves emitted from the underground pipe are detected by moving an ultrasonic receiver on the earth's surface in a direction perpendicular to the axis of the underground pipe, and the ultrasonic detection signal is used to excite the ultrasonic sound source. The method is characterized in that signal processing is performed in synchronization with the signal, and the thickness of the buried pipe is determined based on the waveform width of the detection signal.

According to one embodiment of the invention, the sound waves are ultrasound waves.

According to another embodiment of the invention, the sound waves are low frequency sound waves.

[Embodiments of the invention]

Next, one embodiment of the present invention will be described in detail based on the drawings.

FIG. 1 shows a schematic diagram of an embodiment of the present invention.

1 In Figure 1, a buried pipe, for example, a water pipe 1, is buried underground 2, and a branch pipe 3 is branched from this water pipe 1 and exposed on the ground surface, and is equipped with, for example, a fire hydrant 4. . The underground pipe thickness detection device 5 includes an ultrasonic sound source (in this embodiment, an ultrasonic sound source consisting of a vibrator 6 and a vibrator drive device 7), a synchronization signal detector (lock-in amplifier)8. It consists of an ultrasonic microphone 9, a recorder 10, etc. The vibrator 6 is installed on the outer circumferential surface of the branch pipe 3 or is installed in contact with liquid at the water outlet of a fire hydrant 4, etc., and is driven by the vibrator drive device 7 to connect the water pipe buried underground 2. 1 is ultrasonically excited.

Further, the ultrasonic microphone 9 is movably provided close to or in close contact with the ground surface, and receives weak ultrasonic waves transmitted from the water pipe 1 through the underground 2.

The synchronizing signal detector 8 receives a weak reception wave received by the ultrasonic microphone 9 as a detection signal via a signal line 11, and also receives an excitation signal from the transducer driving device 7, which is an ultrasonic sound source. The detection signal is input as a synchronization signal via the signal line 12, and the detection signal is compared with the synchronization signal to determine the signal component of the detection signal that is synchronized with the synchronization signal, that is, the signal component including an amplitude component signal and a phase component signal. By extracting only those signals, noise is removed and reception sensitivity is increased. During this time, the output signal of the M signal detector 8 is recorded by the recorder 10. Further, XX indicates the axial direction of the water pipe 1, and YY indicates the scanning movement direction of the ultrasonic microphone 9 perpendicular to the axial direction xx.

Next, FIG. 2 is a waveform diagram obtained by processing the detection signal received by the ultrasonic microphone 9, which is moved perpendicularly to the axis of the water pipe, by the synchronization signal detector 8, and then recording it by the recorder IO. The same figure (A) shows the same figure (B) when the water pipe is thick.
) is a waveform diagram when the water pipe is thin. In this FIG. 2, DA is the pipe diameter to the water pipe 1, and DB is the pipe diameter of the water pipe IB. Here, it is assumed that the pipe diameter DA is larger than the pipe diameter DB. Thus, the ultrasonic microphone 9 shown in FIG. 1 is brought close to or in close contact with the ground surface and moved in the moving direction YY. At this time, the water pipe I detected by the ultrasonic microphone 9
Waveforms WA and WB of detection signals from A and IB are water pipe LA
, 1B is highest when the ultrasonic microphone 9 is on the center line of the water pipe IA.

It was actually observed that the distance from the IB rapidly decreases.

Therefore, for pipes buried at the same depth, the waveforms WA and W
It can be seen that the heights Hl and H□ of B are approximately equal, and the widths D+ and Dz approximately correspond to the pipe diameters DA and DB of the water pipes IA and IB. From this, the thickness of the water pipe, that is, the buried pipe, can be detected. At that time, the detection signal is sent to the synchronous detector 8.
Since the detection signal is processed in synchronization with the excitation signal, it is not affected by other noises, and therefore the detection sensitivity is good even though the detection signal is weak.

Although the above description has been made regarding the use of ultrasonic waves as the sound waves, it has been confirmed through experiments that the intended purpose can be achieved even when low frequency sound waves are used as the sound waves.

〔Effect of the invention〕

As explained above, according to the present invention, a buried pipe is acoustically excited through a branch pipe exposed on the ground surface, and the sound wave from the buried pipe is transmitted to a sonic receiver on the ground surface with respect to the axis of the buried pipe. The thickness of the buried pipe can be obtained as the waveform width of the detection signal by detecting the detection signal by moving in a perpendicular direction and processing the detection signal in synchronization with the excitation signal of the sonic sound source. At that time, the detection signal is not interfered with by noise other than the measurement system, so even though the detection signal is weak, it becomes possible to easily and reliably detect the thickness of the underground pipe, and Since it does not require many years of skill, it is easy to handle.

[Brief explanation of drawings]

Fig. 1 is a schematic configuration diagram of an embodiment of the present invention, and Fig. 2 shows a detection signal received by an ultrasonic microphone moved perpendicular to the axis of a water pipe and processed by a synchronous signal detector. The waveform diagram recorded by the rear recorder is shown, and the figure (A> is the waveform l when the water pipe is thick, and the figure (B) is the waveform l when the water pipe is thin. 1-1 Water pipe, 3- ---1 branch pipe, 5--1 underground pipe thickness detection device, 6--1 vibrator, 7--1 vibrator drive device, 8--1 synchronous signal detector (lock-in amplifier)
, 9--1 ultrasonic microphone. Figure 1 (Al CB) Figure 2, page 1 continued 0 Inventor: Hiroshi Ishizuka @ Inventor: Masaru Kono Inventor: Kunio Yamamoto 2-2-1 Nagaita, Yokosuka, Fuji Electric Research Institute, Ltd.

Claims (1)

[Scope of Claims] 1) A sonic sound source installed in a branched pipe branched from a buried pipe buried underground and exposed to the ground surface causes the buried pipe to be sonic-excited, and the radiated sound waves from this buried pipe are generated. is detected by moving a sound wave receiver on the ground surface in a direction perpendicular to the axis of the buried pipe, and the detection signal of the sound wave is processed in synchronization with the excitation signal of the sound wave source, and the detection signal is A method for detecting the thickness of an underground underground pipe, characterized in that the thickness of the underground pipe is determined based on the waveform width of the underground pipe. 2. The method for detecting the thickness of underground pipes according to claim 1, wherein the sound waves are ultrasonic waves. 3) The method for detecting the thickness of underground pipes according to claim 1, wherein the sound waves are low-frequency sound waves.