JPH0362953B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for detecting mortar filling in pipe-in-pipe construction.

BACKGROUND ART In the pipe-in-pipe construction method in which a new pipe is inserted into an existing pipe, mortar is generally injected and filled into the gap between the existing pipe and the new pipe. By the way, since the above gap is usually small,
Without sufficient construction management, unfilled areas often remain. Therefore, it has conventionally been customary to control the total amount of mortar to be injected.

Problems to be Solved by the Invention However, with the method for controlling the total amount of mortar as described above, there is a problem in that local underfilling, lifting of mortar from the tube surface (retention), etc. cannot be detected.

SUMMARY OF THE INVENTION An object of the present invention is to solve these problems and to easily detect localized unfilled areas or looseness caused by mortar management.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides the following methods: Before the mortar filled in the gap between the existing pipe and the new pipe in the pipe-in-pipe construction method is completely hardened, Ultrasonic waves are emitted from the inner surface of the new pipe and the reflected waves are detected.

Effect In this way, for example, ultrasonic waves of about 5 kHz have a large attenuation in the air and hardly transmit, but they have the property of transmitting well in water and metal, so if there is an unfilled part, etc. , the emitted ultrasonic waves are superimposed and reflected on the wall of the new tube, and no significant attenuation is seen in the reflected waves. On the other hand, if there is no unfilled portion, the emitted ultrasonic waves will penetrate the new pipe, the mortar layer, and the existing pipe, and the reflected waves will be greatly reduced. Therefore, by detecting the reflected waves, it is possible to detect the presence of non-filling or the like.

Embodiment Hereinafter, an embodiment of the present invention will be described based on the drawings. First, the principle of the present invention will be explained. Fourth
As shown in the figure, when ultrasonic waves are emitted from the ultrasonic sensor 22 attached to the side wall of an empty iron container 21, the ultrasonic waves are reflected from the B plane, which is generally called superimposed reflection as shown in Fig. 5. You can observe reflected waves. By the way, ultrasonic waves have a characteristic that they are attenuated more when propagating in the air than when propagating in water or metal. Therefore, as shown in FIG. 6, when the inside of the iron container 21 is filled with water 23 and ultrasonic waves are emitted from the ultrasonic sensor 22, the transmittance of the ultrasonic waves on the B side increases, and the seventh
As shown in the figure, the output level of the reflected wave decreases.
In Figure 1, 1 is an existing pipe buried underground;
2 is a new pipe inserted into the existing pipe 1, and 3 is a gap 3 between the existing pipe 1 and the new pipe 2. The gap 3 is injected and filled with mortar 4. Reference numeral 5 denotes an ultrasonic sensor installed on the inner surface of the new pipe 2, which includes an ultrasonic emitting device and a detecting device.

FIG. 2 shows the output waveform of the ultrasonic sensor 5 when the gap 3 has an unfilled portion. here 6
7a, 7b, . . . show reflected waves. The time from the emitted wave 6 to the first reflected wave 7a corresponds to the thickness of the new pipe 2. That is,
Ultrasonic waves of about 5 kHz have a large attenuation in the air and hardly propagate, but they propagate well in water and metal, so the ultrasonic waves emitted from the ultrasonic sensor 5 are transmitted to the new pipe 2. The waveform shown in the figure is detected.

FIG. 3 shows the output waveform of the ultrasonic sensor 5 when the gap 3 is sufficiently filled with mortar 4. In this case, since the emitted wave penetrates the new pipe 2, mortar 4, and existing pipe 1 well, the output level of the reflected waves 7a, 7b, . . . becomes low as shown in the figure.

Therefore, an output level check section is provided after a time sufficiently longer than the thickness of the new pipe 2, and a relay etc. is activated when the output in this section exceeds a certain level. By using a signal processing system, it is possible to determine whether or not the mortar 4 is filled. If it is determined that the mortar 4 is not filled, some measure is taken before the mortar 4 filled in other parts is completely hardened.

Effects of the Invention As described above, according to the present invention, if there is a local unfilled portion of mortar or floating from the tube surface, this can be easily and non-destructively detected.

[Brief explanation of drawings]

Fig. 1 is a sectional view of a main part of an embodiment of the present invention, Fig.
The figure is an output waveform diagram when there is an unfilled part, the third
The figure is an output waveform diagram when there is no unfilled portion, FIG. 4 is an overall configuration diagram of the device for illustrating the principle of the present invention, and FIG. 5 is an output waveform diagram of the device in FIG. 4.
FIG. 6 is an overall configuration diagram of an apparatus for illustrating the principle of the present invention, and FIG. 7 is an output waveform diagram of the apparatus of FIG. 6. 1...Existing pipe, 2...New pipe, 3...Gap, 4...
...Mortar, 5...Ultrasonic sensor.

Claims (1)

[Claims] 1. In the pipe-in-pipe construction method, before the mortar filled in the gap between the existing pipe and the new pipe is completely hardened, ultrasonic waves are emitted from the inner surface of the new pipe toward the gap and the reflected waves are detected. A mortar filling detection method in a pipe-in-pipe construction method characterized by: