JP5067735B2 - Curing state inspection method for lining material - Google Patents

Description

  The present invention relates to a cured state inspection method for inspecting the cured state of a lining material containing a curable resin disposed inside an existing pipe.

Pipings buried mainly in the ground such as water and sewage pipes and gas conduits are deteriorated due to various factors such as corrosive gas and ground subsidence, for example, when used for a long period of time. As a method for repairing such deteriorated piping, there is a so-called rehabilitation method. In this method, for example, a lining material (for example, FRP (Fiber Reinforced Plastic)) containing a curable resin or the like is inserted into a deteriorated pipe, the resin is cured by heat or light, and the inner surface of the pipe has a predetermined thickness. The pipe is rehabilitated by covering with a lining material or forming a new pipe.
In piping (rehabilitated pipe) rehabilitated by such a rehabilitation method, for example, an inspection device and a method for inspecting the thickness of the lining material of the rehabilitated pipe have been studied as quality control after construction (Patent Literature). 1).

Japanese Patent No. 3925470

In the rehabilitation method using a lining material containing a curable resin, if the curable resin contained in the lining material is not sufficiently cured after construction, it is likely to deteriorate in the non-cured part, or the inner surface of the rehabilitated pipe due to external pressure There is a risk that the quality of the rehabilitated pipe will deteriorate, such as swelling. Therefore, it is important to grasp the cured state of the curable resin.
However, as described in Patent Document 1, although the method for inspecting the thickness of the lining material of the rehabilitated pipe has been studied conventionally, in order to grasp the cured state of the curable resin contained in the lining material. There is almost no examination about the inspection method, and there is no established inspection method at present.

  An object of this invention is to provide the hardening state test | inspection method for test | inspecting the hardening state of the lining material containing the curable resin arrange | positioned inside the existing pipe | tube in view of the said situation.

Means and effects for solving the problems

The method for inspecting the cured state of a lining material according to the present invention relates to a method for inspecting the cured state of a lining material containing a curable resin disposed inside an existing pipe.
And the hardening state inspection method of the lining material which concerns on this invention has the following some features, in order to achieve the said objective. That is, the method for inspecting the cured state of the lining material of the present invention comprises the following features alone or in combination as appropriate.

Features that put the cured state inspection method of lining material according to the present invention, the curing conditions for inspecting a hardened condition of the lining material comprising a curable resin disposed within the existing pipe in order to achieve the object In the inspection method, two types of ultrasonic waves having different frequencies are transmitted from the inner surface side of the lining material toward the thickness direction of the lining material, from the boundary between the lining material and the existing pipe. the reflection echo is detected, respectively, is to estimate the cured state of the lining material on the basis of the difference between the maximum amplitude value of their echo.

The inventor of the present application knows that the maximum amplitude value of the reflected echo changes corresponding to the cured state of the lining material, and is arranged inside the existing pipe by using the inspection method of the above configuration. The cured state of the lining material can be measured.
Moreover, according to this structure, since it can measure by transmission of an ultrasonic wave and detection of a reflective echo, it can test | inspect easily, without destroying a lining material.
Further, for example, by using an ultrasonic transmitter and a receiver used for measuring the thickness of the lining material, the cured state can be measured simultaneously with the thickness measurement or the like. This makes it possible to efficiently measure information necessary for quality control of the rehabilitation pipe.

Further, two types of ultrasonic waves having different frequencies are transmitted to detect the reflected echoes, and the cured state of the lining material is estimated based on the difference between the maximum amplitude values .

  According to this configuration, variation in the measurement result of the cured state can be reduced. Thereby, the hardening state of a lining material can be estimated more reliably by a simple method.

  Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings.

(About inspection target)
FIG. 1 is a diagram schematically showing a sewer pipe 2 in which a lining material 1 is disposed. The lining material 1 is an inspection object by the cured state inspection method of the present invention. The lining material 1 is arranged on the inner surface of the sewer pipe 2 by using an existing pipe rehabilitation method such as a reversal method or a forming method. In some cases, the lining material is bonded to the inner surface of the existing pipe, and in other cases, the lining material is not bonded to the inner surface of the existing pipe.

  Here, the reversal method is, for example, inserting a hose material containing a thermosetting resin into an existing pipe while being reversely pressurized, and heating the resin in a pressurized state in the existing pipe, so that the inner surface of the existing pipe It is a method of attaching a hose material or forming a new pipe. The forming method is, for example, drawing a hose material containing a thermosetting resin into an existing pipe, expanding and heating the hose material with air and steam, and pasting the hose material on the inner surface of the existing pipe, or This is a method of forming a new pipe. In these rehabilitation methods, for example, when a hose material containing a photo-curing resin such as an ultraviolet-curing resin is used, the resin is cured by irradiating light such as an ultraviolet-ray, so that the hose material is disposed on the inner surface of the existing pipe It is also possible to stick it on or form a pipe.

  1 shows the lining material 1 arranged in the sewer pipe 2. However, the lining material 1 is not limited to the lining material 1, and is a lining material arranged in an existing pipe such as a water pipe or a gas conduit. However, it can test | inspect using the hardening state inspection method of this invention.

  The lining material 1 is composed of, for example, a sheet (SMC) made of a thickened curable resin liquid and a fiber material, or a material obtained by impregnating a long fiber material with a thermosetting resin liquid. As the thermosetting resin, for example, an unsaturated polyester resin that is cured by heating at about 80 ° C. for a predetermined time is used. For example, glass fiber is used as the fiber material included in the lining material 1.

  If the cured state inspection method of the present invention is used, not only when an unsaturated polyester resin is used as the thermosetting resin, but also when other thermosetting resins such as an epoxy resin are used. Even if it exists, the hardening state of a lining material can be test | inspected. Moreover, even if it is the case where carbon fiber, an aramid fiber, etc. are used not only when the glass fiber is used as a fiber material of the lining material 1, the hardening state of a lining material can be test | inspected. . Furthermore, even when the lining material 1 contains a photocurable resin and is cured by light irradiation, the cured state can be inspected.

(Inspection method)
Hereinafter, the hardening state inspection method of the lining material according to the embodiment of the present invention will be described.
FIG. 2 is a diagram schematically showing a state in which the ultrasonic probe 3 included in the inspection apparatus used for carrying out the present invention is installed on the inner surface of the lining material 1. The ultrasonic probe 3 is connected to an inspection apparatus main body (not shown) via a cable 4.

  This inspection apparatus has a substantially cylindrical ultrasonic probe 3, and ultrasonic waves are transmitted from a circular end surface 3 a of the ultrasonic probe 3. Further, the inspection apparatus detects the reflected echo of the transmitted ultrasonic wave, the amplitude of the reflected echo, and the time from when the ultrasonic wave is transmitted until the reflected echo is detected (hereinafter referred to as propagation time). Can be measured. In addition, the frequency of the transmitted ultrasonic wave can be changed as appropriate by changing the type of the ultrasonic probe 3.

  A contact medium such as glycerin paste is applied to the inspection position on the inner surface of the lining material 1. The end surface 3a at which the ultrasonic wave is transmitted from the ultrasonic probe 3 is pressed against the inspection position where the contact medium is applied. The ultrasonic probe 3 is disposed on the inner surface of the lining material 1 with the end surface 3a facing vertically downward, for example, and a weight 5 having a predetermined load is installed at the other end of the ultrasonic probe 3. Thereby, the end surface 3 a is pressed against the inner surface of the lining material 1 with a constant force. Further, ultrasonic waves are transmitted from the ultrasonic probe in the thickness direction of the lining material 1.

  FIG. 3 is a graph showing measurement results obtained by transmitting ultrasonic waves from the ultrasonic probe 3 with a delay material to the lining material 1 and measuring the reflected echoes. In FIG. 3, the horizontal axis represents the ultrasonic wave propagation time (μs), and the vertical axis represents the amplitude voltage value (V) of the reflected echo. The measurement result is obtained by transmitting an ultrasonic wave having a frequency of 4 MHz. The diameter (oscillator diameter) of the end surface 3a of the ultrasonic probe 3 is about 10 mm, and measurement is performed by urging the ultrasonic probe 3 vertically downward with a 200 g weight 5.

  As shown in FIG. 3, a reflected echo (indicated by an arrow X in FIG. 3; hereinafter referred to as a surface echo) reflected from the inner surface of the lining material 1 when the propagation time is about 11 μs is detected. Further, when the propagation time is between about 16 μs and 17 μs, a reflected echo (indicated by an arrow Y in FIG. 3, hereinafter referred to as a bottom surface echo) reflected at the boundary between the lining material 1 and the sewer pipe 2 is detected. Yes.

  The bottom echo is a reflected echo detected after a predetermined time from the propagation time when the surface echo is detected. The predetermined time is determined based on the speed of the ultrasonic wave propagating through the lining material 1 and the thickness of the lining material 1. In this embodiment, the propagation time at which the bottom echo is detected is estimated from the waveform of the reflected echo obtained in the experiment performed in advance, and the maximum amplitude voltage value of the reflected echo detected at the estimated propagation time is calculated as the bottom echo. The maximum amplitude voltage value. Specifically, the maximum amplitude voltage value of the reflected echo measured during the propagation time of 15 μs to 18 μs is set as the maximum amplitude voltage value of the bottom echo. In addition, since the amplitude voltage value is measured in a positive / negative manner, the amplitude voltage value having the largest absolute value among the amplitude voltage values measured during the propagation time of 15 μs to 18 μs may be set as the maximum amplitude voltage value.

  FIG. 4 shows the measurement results of measuring ΔH, which will be described later, for three types of lining materials (lining material A1, lining material A2, and lining material A3) having different cured states. FIG. 4A shows the measurement result of the lining material A1, FIG. 4B shows the measurement result of the lining material A2, and FIG. 4C shows the measurement result of the lining material A3. In addition, the thickness of each lining material A1-A3 is about 6 mm, The said measurement was performed rapidly after preparation of lining material A1-A3.

In this measurement, ultrasonic waves having frequencies of 1 MHz, 2 MHz, 3 MHz, 4 MHz, and 5 MHz are transmitted, respectively, and the maximum amplitude voltage values V ₁ , V ₂ , V ₃ , V ₄ , V ₅ (hereinafter referred to as V _{x) of the} bottom echo. Measured). Then, the measured maximum amplitude voltage value V _x is converted into the bottom echo height H _x (dB) based on the following calculation formula (i). In the present embodiment, the bottom echo height H _x corresponds to the maximum amplitude value of the reflected echoes in the present invention.
H _x = 20 × log (A ′ / A) − (measurement gain−reference gain) (i)
A is a voltage reference value. In the present embodiment, the maximum amplitude voltage value of the bottom echo obtained by producing a fully cured sample for each thickness of the lining material and performing the ultrasonic measurement described above is used as the voltage reference value for each thickness. A ′ is the ratio of the maximum amplitude voltage value V _x when A is 100%. The measurement gain and the reference gain are amplification levels set in each measurement in order to make the voltage value easy to read.
Then, the difference between the bottom echo height H ₁ as measured with a frequency of the bottom echo height H _x and 1MHz at each measuring frequency (i.e., the maximum difference in amplitude value) is [Delta] H (= H _x - H ₁ ) is obtained.

  FIG. 4 shows the relationship between the frequency of the transmitted ultrasonic wave (horizontal axis) and ΔH (vertical axis) at each frequency, and the installation position of the ultrasonic probe 3 on the lining material is changed. The value of ΔH measured four times is plotted.

Moreover, the lining material A1 whose measurement results are shown in FIG. 4 (a) is a lining material that is completely cured by heating at 100 ° C. or higher for a predetermined time (4 hours).
The lining material A2 whose measurement results are shown in FIG. 4B is a lining material that is cured by heating at 80 ° C. for a predetermined time (4 hours).
The lining material A3 whose measurement results are shown in FIG. 4C is a lining material that is cured by heating at a lower temperature (about 70 ° C.) than the lining material A2 for a predetermined time (4 hours).

  Thus, since the lining materials A1 to A3 have different heating conditions, their cured states are different from each other. Qualitatively speaking, the lining material A1 is most cured, and the degree of curing decreases in the order of the lining material A2 and the lining material A3.

  As shown in FIG. 4, in the same material, it can be seen that ΔH decreases as the frequency of ultrasonic waves to be transmitted increases. Moreover, when FIG. 4A, FIG. 4B, and FIG. 4C are compared, the slope of the graph (the ratio of the decrease in ΔH with respect to the increase in frequency) is that of the lining material A1 (FIG. 4A). The smallest is the lining material A3 (FIG. 4C). That is, it can be seen that the lining material having a lower degree of curing has a higher rate of decrease in ΔH due to an increase in frequency, and the measurement data of the lining material having a higher degree of curing has a lower rate of decrease in ΔH due to an increase in frequency.

  In other words, when ΔH is measured by transmitting ultrasonic waves of the same frequency, it can be seen that the value of ΔH measured for the lining material having a lower degree of curing becomes smaller. Moreover, it turns out that the difference of (DELTA) H measured with the lining material of a different hardening degree becomes large, so that the frequency to transmit is large. That is, when the measurement results of FIG. 4A, FIG. 4B, and FIG. 4C are compared, the difference in the value of ΔH when measuring by transmitting an ultrasonic wave having a frequency of 5 MHz is most remarkable. .

FIG. 5 shows measurement results obtained by measuring the relationship between ΔH of the lining material after the elapse of a predetermined time from the production and the frequency of the ultrasonic wave.
As shown in FIG. 5, for the lining material that has been produced for a predetermined period of time, as in the measurement results shown in FIG. 4, ΔH becomes smaller as the frequency of the ultrasonic wave to be transmitted increases, Further, comparing FIG. 5A, FIG. 5B, and FIG. 5C, it can be seen that the rate of decrease in ΔH due to the increase in frequency (the slope of the graph) increases as the lining material has a lower degree of curing. .

When a cured state is determined using a cured state inspection method of the present invention for a lining material whose cured state is unknown (hereinafter referred to as a measurement target), first, an ultrasonic wave is applied to the measurement target and ΔH (= H _x −H ₁ ) Measure. After that, by comparing the measured ΔH value with the experimental data shown in FIGS. 4 (a), 4 (b), and 4 (c), the measurement target is any of the lining materials A1, A2, and A3. It can be estimated whether the corresponding cured state.

Specifically, for example, when the ultrasonic frequency is 5 MHz and 1 MHz, the bottom surface echo height ΔH (= H ₅ −H ₁ ) of the measurement target is measured, and the ΔH is measured with reference to FIGS. It can be compared with the value of ΔH of 5 MHz (horizontal axis) in (b) and FIG. Thereby, it can be estimated that the cured state of the measurement target is a cured state corresponding to the lining material (A1, A2, or A3) having the closest value of ΔH.

Further, for example, when the ultrasonic frequency is 1 MHz, 2 MHz, 3 MHz, 4 MHz, and 5 MHz, the bottom surface echo height ΔH (= H _x −H ₁ ) of the measurement target is all measured, and a graph corresponding to FIG. And the slope of the graph can be compared with the slopes of the graphs in FIGS. 4 (a), 4 (b), and 4 (c). Thereby, it can be estimated that the hardening state of a measuring object is a hardening state equivalent to the lining material (A1, A2, or A3) which has the nearest said graph inclination.

  Next, a method for quantitatively estimating the degree of cure of the lining material will be described.

In order to quantitatively estimate the degree of curing of the lining material, differential scanning calorimetry (DSC measurement) was performed on the three types of lining materials A1, A2, and A3 produced under the conditions described above. Since the unsaturated polyester resin used for the lining material in the present embodiment generates heat during curing, it can be said that the greater the amount of heat measured by the DSC measurement, the more uncured portions and the lower the degree of curing (soft). The measurement results of measuring the calorific value from each material are as follows.
Lining material A1 ... 0 (J / g)
Lining material A2 ... 2.4 (J / g)
Lining material A3 ... 5.1 (J / g)
Thereby, it can be quantitatively understood that the lining material A1 has the highest degree of curing, and the lining material A2 has a lower degree of curing than the lining material A1, and has a higher degree of curing than the lining material A3.

FIG. 6 is a graph showing the relationship between DSC heat generation and ΔH in the lining materials A1, A2, and A3 having different cured states. Note that ΔH in FIG. 6 is the difference between the bottom echo height H ₅ when measured using a frequency of ₅ MHz and the bottom echo height H ₁ when measured using a frequency of 1 MHz (ie, ΔH = H ₅ −H ₁ ) is an average value measured 6 times.

When a cured state is determined using a cured state inspection method of the present invention for a lining material whose cured state is unknown (hereinafter referred to as a measurement target), first, an ultrasonic wave is applied to the measurement target and ΔH (= H ₅ −H ₁ ) Measure. Thereafter, based on the measured value of ΔH, the DSC heat generation amount corresponding to the ΔH is obtained from FIG. As described above, since the DSC heat generation amount corresponds to the degree of curing, the cured state of the measurement target can be estimated from the value of the DSC heat generation amount.

  The two frequencies of the ultrasonic waves transmitted to measure the two bottom echo heights necessary for calculating ΔH are such that the higher one of the two frequencies is at least five times the lower frequency. Is desirable. In this case, the change in ΔH with respect to the change in the cured state becomes larger than the variation at the time of measurement, and the cured state can be more reliably determined.

Next, the relationship between the thickness of the lining material and ΔH will be described. FIG. 7 is a graph showing the relationship between ΔH and the thickness of the completely cured lining material. For the measurement, three types of lining materials having thicknesses of about 3 mm, about 6 mm, and about 9 mm were used. ΔH is the difference between the bottom echo height H ₅ when measured using a frequency of ₅ MHz and the bottom echo height H ₁ when measured using a frequency of 1 MHz (ie, ΔH = H ₅ − H ₁ ).

  As shown in FIG. 7, ΔH varies depending on the thickness of the lining material, and it can be seen that ΔH tends to decrease as the thickness of the lining material increases. In FIG. 6, the reference curve for the lining material having a thickness of about 6 mm is exemplarily shown. However, in order to inspect the cured state of the lining material having different thicknesses, it corresponds to the thickness of the measurement target. It is necessary to obtain the reference curve in advance.

  As described above, the cured state inspection method for the lining material according to the present embodiment is a cured state inspection method for inspecting the cured state of the lining material 1 including the curable resin disposed inside the sewer pipe 2. The ultrasonic wave is transmitted from the inner surface side of the lining material 1 toward the thickness direction of the lining material 1 to detect reflection echo (bottom surface echo) from the boundary between the lining material 1 and the sewer pipe 2. Then, the cured state of the lining material 1 is estimated based on the maximum amplitude value (bottom echo height) of the reflected echo.

As shown in FIG. 6, ΔH calculated from the bottom echo height of the reflected echo changes in accordance with the cured state of the lining material. Therefore, by using the inspection method having the above configuration, the inside of the sewer pipe 2 can be obtained. It becomes possible to measure the cured state of the lining material 1 arranged on the surface. In both cases where the lining material is bonded to the existing pipe inner surface and the lining material is not bonded to the existing pipe inner surface, the cured state can be measured by the same inspection method. It is.
Moreover, according to this structure, since it can measure by transmission of an ultrasonic wave and detection of a reflective echo, it can test | inspect without destroying the lining material 1. FIG.
In addition, for example, by using an ultrasonic transmitter and a receiver that have been conventionally used for measuring the thickness of the lining material 1, the cured state can be measured simultaneously with the thickness measurement or the like. This makes it possible to efficiently measure information necessary for quality control of the rehabilitation pipe.

Also, two types (1 MHz, 5 MHz) of ultrasonic waves having different frequencies are transmitted to detect bottom surface echoes, ΔH is calculated from the bottom surface echo heights H ₁ and H ₅ , and the lining material is based on the ΔH. The state of hardening of is estimated. According to this configuration, variation in the measurement result of the cured state can be reduced.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made as long as they are described in the claims.

(1) In the present embodiment, measurement was performed by transmitting an ultrasonic wave in a state where the ultrasonic probe was biased vertically downward by a weight, but the present invention is not limited to this case. For example, the measurement may be performed by pressing the ultrasonic terminal against the inner surface of the lining material 1 with a constant force using a biasing means such as a spring.

(2) The cured state inspection method may further include a step of transmitting ultrasonic waves and measuring the thickness of the lining material to be inspected in the cured state. In this case, for example, reference data indicating the relationship between the cured state of the lining material and ΔH is obtained in advance for a plurality of thickness lining materials, and the thickness data measured by the step of measuring the thickness of the lining material. The reference data corresponding to the measured thickness data is selected from a plurality of reference data, and the cured state of the lining material to be inspected is estimated based on the selected reference data. it can. Thereby, a hardening state can be estimated accurately.

(3) In this embodiment, in order to calculate ΔH, it is necessary to transmit ultrasonic waves of two different types of frequencies to the lining material. For example, using a two-frequency probe, the 2 It is also possible to employ a configuration in which reflected echoes can be measured by simultaneously transmitting ultrasonic waves of various frequencies. In this case, the measurement time can be shortened.

(4) In the present embodiment, ΔH is calculated based on the bottom echo height H _x of the bottom echo obtained by transmitting ultrasonic waves of two types of frequencies of 1 MHz and 5 MHz, and based on the ΔH. However, the present invention is not limited to this case. For example, the hardening state may be estimated based only on the maximum amplitude value (maximum amplitude voltage value or bottom echo height) of the bottom echo obtained by transmitting an ultrasonic wave of one frequency (for example, 5 MHz). it can. Even when ultrasonic waves of the same frequency are transmitted, the cured state of the lining material changes, so that the maximum amplitude value of the bottom surface echo changes corresponding to the cured state. By obtaining data indicating the corresponding relationship, the cured state can be estimated by measurement using ultrasonic waves of a single frequency.

It is a figure which shows typically the sewer pipe with which the lining material was arrange | positioned inside. It is a figure which shows the state which installed the ultrasonic probe which the test | inspection apparatus used in order to implement this invention has on the inner surface of the lining material. It is a graph which shows the measurement result which sent the ultrasonic wave from the ultrasonic probe to the lining material, and measured the reflective echo. The measurement result which measured (DELTA) H about three types of lining materials from which a hardening state differs is shown. It is the measurement result which measured the relationship between (DELTA) H of the lining material after a fixed time progress, and the frequency of an ultrasonic wave after producing. It is a graph which shows the relationship between DSC calorific value and (DELTA) H in the lining material from which a hardening state differs. It is a graph which shows the relationship between the thickness of the lining material fully hardened, and (DELTA) H.

Explanation of symbols

1 Liner 2 Sewer pipe 3 Ultrasonic probe 4 Cable 5 Weight X Surface echo Y Bottom echo

Claims (1)

It is a cured state inspection method for inspecting the cured state of a lining material including a curable resin disposed inside an existing pipe,
Two types of ultrasonic waves having different frequencies are transmitted from the inner surface side of the lining material toward the thickness direction of the lining material to detect reflection echoes from the boundary between the lining material and the existing pipe, respectively. , cured state inspection method of the lining material and estimates the cured state of the lining material on the basis of the difference between the maximum amplitude value of their echo.

Images