JP5802091B2 - Curing state inspection method for lining material - Google Patents

Description

  The present invention relates to a method for inspecting the cured state of a lining material constructed in a pipeline.

  Conventionally, lining materials have been installed on the inner surface of pipes that have been buried underground, such as aging water and sewage pipes, agricultural water pipes, and gas pipes (rehabilitation and rehabilitation). Also known as construction method). In a general rehabilitation method, a lining material impregnated with a curable resin is inserted into a pipeline, and the resin is cured through a curing process such as heating or ultraviolet irradiation, so that the inside of the pipeline is strong. Build a reinforced structure (rehabilitation pipe).

  By the way, in the above rehabilitation method, if the curable resin contained in the lining material is not sufficiently cured after the lining material is applied, it is likely to deteriorate in the uncured portion or the inner surface of the lining material due to external pressure. The quality of the rehabilitation pipe will deteriorate, such as swelling. Therefore, it is important to grasp the cured state of the curable resin after construction.

  In this regard, Patent Document 1 discloses a method for inspecting the cured state of the lining material using ultrasonic waves. In the inspection method disclosed in Patent Document 1, an ultrasonic transmitter (ultrasonic transmission probe) and an ultrasonic receiver (ultrasonic reception probe) are arranged in a pipeline at a distance from each other. While transmitting ultrasonic waves from the sound wave transmitter toward the lining material, the ultrasonic wave propagated through the lining material is received by the ultrasonic receiver. Here, when the curable resin of the lining material is in an uncured state, since the ultrasonic wave is attenuated and difficult to propagate compared to the cured state, the received waveform received by the ultrasonic receiver (particularly, The amplitude of the peak when receiving the ultrasonic wave propagating through the inside of the lining material is different. Therefore, it can be determined from the waveform of the ultrasonic wave received by the ultrasonic receiver whether or not the curable resin of the lining material is sufficiently cured.

JP 2009-250755 A

  In the inspection method described in Patent Literature 1 described above, if the attenuation of ultrasonic waves inside the lining material is small, such as when the inside of the lining material is made of a uniform material, the inside of the lining material has propagated. The amplitude of the peak of the received waveform that occurs when an ultrasonic wave is received becomes large, and this peak is relatively easy to detect.

  However, when the attenuation of the ultrasonic wave inside the lining material is large, the amplitude of the peak of the received waveform becomes small and it becomes difficult to detect the peak. For example, many lining materials are not composed of only a curable resin, but are usually composed of a combination of a plurality of different materials including reinforcing fibers that ensure strength. In the lining material having such a configuration, the ultrasonic wave is attenuated by reflection at the interface between different materials in the middle of propagation of the ultrasonic wave inside the lining material, so that the amplitude of the peak is reduced. In such a case, it becomes easy to be affected by noise, it becomes difficult to detect a peak, and there is a possibility that the determination of curing / non-curing is mistaken.

  An object of the present invention is to facilitate detection of a peak of a received waveform and to increase the accuracy of determination of a cured state.

Means for Solving the Problems and Effects of the Invention

The cured state inspection method for a lining material of the present invention is a method for inspecting the cured state of a lining material including a curable resin disposed in a pipeline, wherein the ultrasonic transmitter and the ultrasonic receiver are An installation step of installing a distance along the inner surface of the lining material, and transmitting ultrasonic waves of a predetermined frequency from the ultrasonic transmitter toward the lining material, and transmitting the ultrasonic waves propagated through the lining material An ultrasonic measurement step received by an ultrasonic receiver, and a determination step of determining a cured state of the lining material based on an ultrasonic waveform received by the ultrasonic receiver,
In the determination step, when synthesizing the reception waveform received by the ultrasonic receiver and the waveform shifted in time by one cycle of the ultrasonic wave that is the reciprocal of the predetermined frequency with respect to the reception waveform , The hardened state of the lining material is determined based on a composite waveform obtained by synthesizing 3 to 7 waveforms that are shifted in time by one period of the ultrasonic wave including the received waveform. It is.

In the present invention, the cured state of the lining material is determined based on the received waveform when the ultrasonic wave transmitted from the ultrasonic transmitter propagates through the lining material and is received by the ultrasonic receiver. Further, in this determination step, a synthesized waveform is generated by synthesizing a waveform shifted in time with respect to the received waveform with the received waveform of the ultrasonic receiver. In this synthesized waveform, the amplitude of the peak is increased by overlapping the peaks of two or more waveforms, and the noise contained in each waveform is canceled to reduce the influence of the noise. Peak detection is easy. Therefore, it is prevented that the cured state is erroneously determined, and the determination accuracy is improved.
The “peak” in the present specification is not a single point with a large amplitude, but a concept that indicates the entire waveform portion having a large amplitude over a certain range including the single point and the front and back portions. .

Here, if the time difference between the waveform synthesized with the received waveform and the received waveform is large, the peaks do not overlap when the two waveforms are synthesized. In the present invention, by using a waveform that is slightly shifted by one period of the ultrasonic wave with respect to the received waveform, the peaks of the two waveforms almost overlap each other, and the amplitude of the peak of the combined waveform can be increased.

In addition, if the number of waveforms to be synthesized is increased, the peak amplitude will increase, but even if the number of waveforms to be synthesized is increased beyond a certain level, the peak amplitude of the synthesized waveform will peak and will not increase any further. Therefore, it is useless if the number of waveforms to be superimposed is too large. Therefore, it is preferable to generate a synthesized waveform by synthesizing 3 to 7 waveforms including the received waveform.

It is a longitudinal cross-sectional view of the pipe line which is the object of the rehabilitation method concerning this embodiment. It is sectional drawing of a lining material. It is sectional drawing of the pipe line at the time of test | inspecting the hardening state of a lining material. It is a figure which shows the received waveform of the lining material comprised only with unsaturated polyester resin. It is a figure which shows the received waveform of the lining material of the multilayer structure shown in FIG. It is a figure which shows the synthetic | combination waveform produced | generated from the received waveform of FIG. It is a figure which shows the synthetic | combination waveform produced | generated from the received waveform of FIG. It is a figure which shows the measurement point of the test body used for verification of the determination method. It is a figure which shows the synthetic | combination waveform produced | generated from the received waveform in each measurement point of FIG. It is a graph which shows the bending test result of the test piece cut out in each measurement point. It is a graph which shows the unhardened index | exponent of each measurement point. It is a graph which shows the relationship between an unhardened index and a bending elastic modulus.

  Next, an embodiment of the present invention will be described. This embodiment is an example to which the present invention is applied when rehabilitating existing pipelines such as sewers buried in the ground.

(Outline of rehabilitation method)
First, a method for rehabilitating a pipeline using a lining material will be described. FIG. 1 is a longitudinal sectional view of a pipeline to be rehabilitated according to the present embodiment. As shown in FIG. 1, the lining material 1 is a cylindrical body containing a curable resin. After the lining material 1 is drawn into the pipe line P from the manhole M, an inner pressure is applied to the lining material 1 to the pipe line. By curing the curable resin in a state of being pressed against the inner surface of P, a new rehabilitation pipe is formed on the inner surface of the aged existing pipeline P. Further, as the curable resin, a thermosetting or photocurable resin can be used. In the case of thermosetting, the resin is cured by heating, and in the case of photocurable, it is cured by irradiation with light such as ultraviolet rays.

  The lining material 1 can be used in various configurations as long as it contains a curable resin. However, in order to ensure a certain level of strength, it is possible to use curable fibers such as glass fiber, aramid fiber, and carbon fiber. So-called FRP impregnated with a resin liquid can be suitably used.

  An example of the lining material 1 is shown below. FIG. 2 is a cross-sectional view showing an example of the lining material. The lining material 1 shown in FIG. 2 has a sheet material (sheet molding compound: SMC) in which a reinforcing fiber such as a glass fiber is dispersed in a thermosetting resin such as a thickened unsaturated polyester resin as a base material 2, and is tubular. Cylindrical fabrics 3 and 4 woven with polyester fibers or the like are arranged on the outer side and the inner side of the base material 2 that is rolled up. A synthetic resin coating 5 is formed on the inner surface of the inner tubular fabric 4. The tubular woven fabric 3 is impregnated with a thermosetting resin.

  In addition, as the base material 2, in addition to the above SMC, a nonwoven fabric impregnated with a curable resin liquid can also be used. Moreover, the cylindrical fabrics 3 and 4 may be provided only on either the inside or the outside, and further, the cylindrical fabrics may not be provided. Or the structure by which the glass roving cloth was laminated | stacked on the base material 2 which consists of SMC etc. may be sufficient. Further, the synthetic resin coating 5 may be omitted.

(Method for inspecting the curing state of lining material)
Next, a method for inspecting the cured state of the curable resin of the lining material 1 described above will be described. FIG. 3 is a cross-sectional view of a pipeline when inspecting the cured state of the lining material. As shown in FIG. 3, first, an ultrasonic transmitter 10 and an ultrasonic receiver 11 (hereinafter simply referred to as “transmitter 10” and “receiver 11”) are connected to the lining material 1 in the pipe P. Install at a distance along the inner surface (installation process). The transmitter 10 and the receiver 11 are connected to a measuring device 12 (controller). In FIG. 3, the transmitter 10 and the receiver 11 are arranged along the circumferential direction of the pipe P. However, the arrangement direction is not limited to this, and for example, the longitudinal direction of the pipe P (FIG. 3). The transmitter 10 and the receiver 11 may be arranged apart from each other in the direction orthogonal to the paper surface of FIG. In the present embodiment, the transmitter 10 and the receiver 11 are brought into contact with the inner surface of the lining material 1 respectively.

  Next, an ultrasonic wave having a predetermined frequency (for example, 180 kHz) is transmitted from the transmitter 10 toward the lining material 1. Although the ultrasonic wave transmitted from the transmitter 10 propagates through the inside of the lining material 1, a part of the ultrasonic wave propagates to the receiver 11 along the circumferential direction of the lining material 1 as shown by a broken line in FIG. 11 (ultrasonic measurement process). Then, the receiver 11 sends an ultrasonic reception signal (reception waveform) to the measurement device 12. In FIG. 3, the ultrasonic wave transmission direction of the transmitter 10 is a direction perpendicular to the lining material 1 (tube diameter direction), but the pipe diameter direction is set so that the ultrasonic waves can easily propagate in the circumferential direction. May be transmitted in a direction inclined to the receiver 11 side.

  Further, as mentioned above, in this embodiment, the transmitter 10 and the receiver 11 are respectively brought into contact with the inner surface of the lining material 1 (contact method). In this contact method, compared with the non-contact method, when the ultrasonic wave is transmitted from the transmitter 10 toward the lining material 1, and the ultrasonic wave propagated through the inside of the lining material 1 is received by the receiver 11. When it comes to noise, it becomes difficult to ride. Therefore, it is possible to lower the transmission frequency of ultrasonic waves. Moreover, since it does not pass through the air layer, attenuation of ultrasonic waves can be suppressed.

  The measuring device 12 determines the cured state of the curable resin of the lining material 1 based on the received waveform sent from the receiver 11. When the ultrasonic wave propagating through the inside of the lining material 1 is received by the receiver 11, a peak occurs in the received waveform. Here, in the state where the curable resin of the lining material 1 is completely cured and the state where the curing is insufficient (uncured state), the ease of propagation of ultrasonic waves is different, and in the uncured state, Compared with a completely cured state, the ultrasonic wave is easily attenuated during propagation. Accordingly, a difference occurs in the intensity (that is, the amplitude of the peak) of the ultrasonic wave received by the receiver 11, so that the cured state can be determined.

  The received waveform will be further described below with a specific example. 4 and 5 show examples of received waveforms of the receiver 11, respectively. FIG. 4 is a received waveform when ultrasonic waves are transmitted to the lining material 1 (thickness 3 mm) composed only of the unsaturated polyester resin that is a curable resin. FIG. 5 shows a received waveform when an ultrasonic wave is transmitted to the lining material 1 (thickness 15 mm) having the multilayer structure shown in FIG. 4 and 5, the horizontal axis indicates the elapsed time (unit: μs) since one ultrasonic wave is transmitted, and the vertical axis indicates the voltage value of the received waveform (the intensity of the received ultrasonic wave). Indicates. 4 and 5, the transmission frequency is 180 kHz, and both are reception waveforms in a state where the curable resin is cured.

  4 and 5, a peak P1 occurs immediately after the transmission of the ultrasonic wave. This is because the ultrasonic wave transmitted from the transmitter 10 is reflected on the surface of the lining material 1 immediately after that, and the lining material 1 It shows that it has been received by the receiver 11 by propagating on the surface.

  Thereafter, in FIGS. 4 and 5, another peak (peak P2) appears after a lapse of a certain time (after about 70 μs in FIG. 4 and after about 50 μs in FIG. 5). It shows that the ultrasonic wave propagating through the inside is received by the receiver 11 for the first time. In the following description, “peak” does not refer to one point having a large amplitude, but refers to the entire waveform portion whose amplitude has increased over a certain range, including that one point and the preceding and following portions. To do.

  By the way, when the lining material is composed of a single material (only curable resin), as shown in FIG. 4, the amplitude of the peak P2 in the cured state is larger than before and after that, and the peak P2 is detected. Is relatively easy. However, in the lining material containing other materials such as glass fiber in addition to the curable resin, the amplitude of the peak P2 is small even in the cured state as shown in FIG. 5, and it is difficult to detect the peak P2. Become. The reason for this is that the lining material 1 in FIG. 2 is made of a plurality of types of materials in which a base material 2 in which glass fibers are dispersed in a curable resin, cylindrical fabrics 3 and 4, and a resin coating 5 are laminated. This is because the ultrasonic wave is attenuated by the reflection of the ultrasonic wave at the interface between different materials when the ultrasonic wave propagates through the lining material 1 having such a composite structure.

  Accordingly, the following operation is performed by the measuring device 12 so that the peak P2 can be easily detected even in the lining material containing a material other than the curable resin. First, one or more waveforms shifted in time with respect to the received waveform received by the receiver 11 are generated. Then, one or more waveforms that are shifted in time with respect to the received waveform are superimposed on the received waveform on the same time axis to generate a composite waveform.

  FIG. 6 is a waveform diagram of a composite waveform generated from the received waveform of FIG. FIG. 7 is a waveform diagram of a composite waveform generated from the received waveform of FIG. Here, a waveform that is shifted by one period of ultrasonic waves (reciprocal time of the transmission frequency) with respect to the received waveform is generated and synthesized with the received waveform. For example, “two waves” in FIGS. 6A and 7A are obtained by superimposing two waveforms, that is, a received waveform and a waveform shifted by one cycle with respect to the received waveform. In addition, “3 waves” in (b) means that a total of three waveforms, that is, a received waveform, a waveform shifted by one cycle with respect to the received waveform, and a waveform shifted by two cycles with respect to the received waveform are superimposed. Yes.

  First, in the lining material made of a single material, the peak P2 appears clearly even in the reception waveform shown in FIG. 4, but in the composite waveform shown in FIG. 6, the amplitude of the peak P2 is further increased. On the other hand, in the lining material 1 including a material other than the curable resin, the amplitude of the peak P2 is not so large in the received waveform of FIG. 5 compared to the waveform portions before and after the received waveform in FIG. In the composite waveform shown, the amplitude of the peak P2 is considerably larger than before and after that, and the peak P2 clearly appears.

  As described above, when two or more waveforms including the received waveform, which are slightly shifted in time, are combined, the peaks P2 of the respective waveforms are overlapped, so that the amplitude of the peak P2 of the combined waveform increases. Detection of the peak P2 becomes easy. Therefore, it is prevented that the cured state is erroneously determined, and the determination accuracy is improved.

  If the amplitude of the peak P2 is simply increased, the reception waveform may be greatly amplified by the measuring device 12, but in this case, noise included in the reception waveform is also amplified. On the other hand, as described above, by generating a waveform that is shifted a little time (for example, one period of ultrasonic waves) from the received waveform and superimposing it on the received waveform, noise contained in each waveform is reduced. Since it cancels out, the influence of noise is reduced. Further, as described above, there is a problem that noise is amplified when the received waveform is simply amplified. In the present application, a clear peak is generated by generating a synthesized waveform without increasing the gain so much. Can be obtained.

  Further, as shown in FIG. 7, in the synthesized waveform, the larger the number of waveforms to be superimposed on the received waveform, the larger the amplitude of the peak P2, but in the synthesized waveform of 8 waves or more, 7 synthesized waveforms. As compared with, the amplitude of the peak P2 is hardly changed. As described above, even if the number of waveforms to be combined is increased beyond a certain level, the peak amplitude of the combined waveform reaches a peak and does not increase any more, so it is useless to increase the number of waveforms to be superimposed. Therefore, it is preferable to generate a synthesized waveform by superimposing 3 to 7 waveforms including the received waveform.

  Further, a method for determining the cured state of the lining material using the above synthetic waveform will be specifically described. As described above, the amplitude (voltage value) of the peak P2 of the received waveform (synthetic waveform) is lower in the uncured portion of the curable resin than in the completely cured portion. Therefore, ultrasonic measurement is performed on a plurality of locations of the lining material 1, and the degree of curing of the curable resin at each measurement point can be determined depending on the level of the voltage of the peak P2 of the resultant composite waveform. .

  In order to establish a specific method for determining the cured state, the following test was performed. Here, a rectangular flat plate of SMC (the same material as the substrate 2 in FIG. 2) in which glass fibers are dispersed in a thermosetting resin (unsaturated polyester resin) was used as a test body. FIG. 8 shows a plan view of the test body, and also shows the positions of measurement points for ultrasonic measurement in the test body. In addition, at the time of preparation of the test body of FIG. 8, the curing state of the curable resin is intentionally different, and the degree of curing of the curable resin is lower as it goes to the right side of FIG. Yes.

  As shown in FIG. 8, the transmitter 10 and the receiver 11 are arranged at a distance in the short direction of the test body 20 and are in contact with the surface of the test body 20, respectively. Was moved in the longitudinal direction of the test body 20, and ultrasonic measurement was performed at 15 measurement points (No. 1 to No. 15) arranged in the longitudinal direction. In addition, after ultrasonic measurement, for each measurement point, a portion (a portion indicated by a white circle) located between the contact position of the transmitter 10 and the contact position of the receiver 11 (a location indicated by a black circle) is used as a test piece. It cut out and the bending test was done about each test piece.

  FIG. 9 shows a composite waveform generated from the received waveform at each measurement point. The composite waveform in FIG. 9 is obtained by superimposing three waves including the reception waveform obtained by the receiver 11, and shows five measurement points 3, 10, 11, 12, and 13, respectively.

  At the measurement point 3 located on the left side in FIG. 8, the amplitude of the peak P2 surrounded by a circle in FIG. 9 is large, and it is considered that the curable resin is sufficiently cured. On the other hand, the peak amplitude is smaller as it is located on the right side of FIG. However, at the measurement point 10 and the measurement point 11, although the amplitude is slightly smaller than that at the measurement point 3, a peak clearly appears. However, the peaks at the measurement points 12 and 13 are very small, and it is considered that these measurement points 12 and 13 are in an uncured state. Moreover, FIG. 10 is a graph which shows the bending test result of the test piece cut out in each measurement point. As shown in FIG. 10, the bending elastic modulus is large at the measurement points 1 to 10, but the bending elastic modulus is small at the measurement points 11 to 15. From the above results, it is understood that there is a correlation between the amplitude (voltage value) of the peak of the combined waveform and the cured state, and it is possible to determine the cured state from the peak voltage value.

Hereinafter, the above determination will be described more specifically. First, an uncured index is calculated by converting the peak voltage value of the composite waveform into decibels for each measurement point. That is, assuming that the peak voltage value is T (unit: V),
Uncured index = -20 log (T)
Is calculated by

  And when the unhardened index | exponent of each measurement point is computed from the peak voltage value of the synthetic | combination waveform of each measurement point shown by FIG. 9, it will become like FIG. Furthermore, when the relationship between the uncured index in FIG. 11 and the flexural modulus shown in FIG. 10 is graphed, it is as shown in FIG.

As shown in FIG. 12, when the uncured index is small, the flexural modulus is large, and conversely, when the uncured index is large, the flexural modulus is small. Therefore, when the uncured index exceeds a certain value, it can be determined that it is in an uncured state. Here, the threshold value of the flexural modulus for determining the cured state is 6700 N / mm ² (indicated by the alternate long and short dash line in FIG. 10), and at the measurement point 10 where the uncured index exceeds 20, the flexural modulus is the above threshold value. Below. Therefore, if it is based on this result, what is necessary is just to determine that it is an uncured state, when an uncured index exceeds 20.

  In this determination method, the peak voltage value is obtained from the composite waveform, and the uncured index is obtained from the peak voltage value, so that the cured state of each part of the lining material 1 can be easily determined from the uncured index value. Can do. In addition, as a result of this determination, when it is found that an uncured part exists in part, the uncured part is obtained by performing a curing step such as heating or light irradiation on the uncured part. Make sure to cure.

  Next, modified embodiments in which various modifications are made to the embodiment will be described. However, the same reference numerals are given to those having the same configuration as in the above embodiment, and the description thereof is omitted as appropriate.

1] In the above embodiment, as a waveform to be superimposed on the received waveform, at least a waveform shifted by one cycle of the ultrasonic wave is superimposed on the received waveform, but the amount of time shift of the superimposed waveform with respect to the received waveform Is not limited to one cycle of the ultrasonic wave. For example, it may be a waveform shifted by two cycles with respect to the received waveform, or may be a waveform shifted by a half cycle. However, if waveforms having a time shift that is too large are overlapped, the peaks P2 of the two waveforms do not overlap each other, and the amplitude of the peak P2 of the combined waveform does not increase. Therefore, the time lag between the waveforms to be overlapped is shorter than the full width (time width) of the peak P2 of the received waveform, more preferably less than half the full width of the peak P2, so that the peaks P2 overlap each other. Short time.

2] In the above embodiment, the transmitter 10 and the receiver 11 are brought into contact with the inner surface of the lining material 1, but the transmitter 10 and the receiver 11 are arranged apart from the inner surface of the lining material 1. A method may be adopted.

1 Lining material 10 Ultrasonic transmitter 11 Ultrasonic receiver

Claims (1)

A method for inspecting the cured state of a lining material containing a curable resin disposed on an inner surface of a pipeline,
An installation step of installing an ultrasonic transmitter and an ultrasonic receiver at a distance along the inner surface of the lining material;
An ultrasonic measurement step of transmitting ultrasonic waves of a predetermined frequency toward the lining material from the ultrasonic transmitter, and receiving ultrasonic waves propagated through the lining material by the ultrasonic receiver;
A determination step of determining a cured state of the lining material based on an ultrasonic waveform received by the ultrasonic receiver; and
In the determination step, when synthesizing the reception waveform received by the ultrasonic receiver and the waveform shifted in time by one cycle of the ultrasonic wave that is the reciprocal of the predetermined frequency with respect to the reception waveform , The lining is characterized by determining a cured state of the lining material based on a synthesized waveform obtained by synthesizing 3 to 7 waveforms that are shifted in time by one period of the ultrasonic wave including the received waveform. Method for inspecting the cured state of the material.