JP5815921B2 - Defect evaluation apparatus for underground structure, defect evaluation method for underground structure, and defect evaluation program for underground structure - Google Patents

Description

  The present invention relates to a soil structure defect evaluation apparatus, a soil structure defect evaluation method, and a soil structure defect evaluation program.

  Defect evaluation equipment for underground structures is an equipment that evaluates defects in corroded areas where metal pillars such as panzer masts are buried in the ground, especially near the surface of the earth (hereinafter referred to as “ground”). is there. A specific evaluation method for a conventional defect is that an ultrasonic wave set to a predetermined frequency for forming a reflected wave from an exposed portion of a metal column at a corroded portion on the ground is transmitted from the probe and transmitted. The evaluation is performed by analyzing the reflected wave from the corroded part caused by ultrasonic waves. Among these underground structure defect evaluation apparatuses, the following contents are disclosed in Patent Document 1 below. According to Patent Document 1, when receiving and storing a reflected wave from a corroded portion on the ground by ultrasonic waves of a predetermined frequency transmitted from a probe, soil obtained together with the reflected wave from the corroded portion. The reflected wave from the end portion on the buried side is also memorized, and the degree of defect due to corrosion is evaluated by comparing the stored corrosion portion and the echo height of the reflected wave from the end portion.

JP 2004-361321 A

  However, in Patent Document 1, when receiving the reflected wave from the corroded portion on the ground, the reflected wave from the end is also received, so that the ultrasonic wave is scattered while propagating through the metal column. In some cases, the waveform data of the reflected wave from the end portion is almost buried in noise. As a result, the accuracy of the degree of defects due to subterranean corrosion was sometimes inaccurate.

  The object of the present invention has been made in view of the above-mentioned problems, and is a device for evaluating a defect in a soil structure that can more accurately evaluate the degree of a defect due to corrosion, and a defect in the soil structure. It is to provide an evaluation method and a defect evaluation program for a structure in the soil.

  According to the present invention, a defect evaluation apparatus for an underground structure that evaluates the degree of defects due to corrosion of a metal column existing in a soil portion is attached to an outer portion of the metal column in the soil and receives ultrasonic waves having a predetermined frequency. A probe for transmitting toward the soil side and detecting a reflected wave and an ultrasonic flaw detector for receiving the reflected wave detected by the probe are included. The reflected wave is a reflected wave from the end of the metal column on the soil side, is an end reflected wave having the first frequency, and is a reflected wave from the corroded portion of the metal column on the soil side. And a corroded portion reflected wave having a second frequency higher than the first frequency. The ultrasonic flaw detector includes receiving means for individually receiving the corrosion portion reflected wave and the end portion reflected wave.

  Preferably, the receiving means includes switching means for selectively receiving the corroded portion reflected wave and the end reflected wave.

  More preferably, the ultrasonic wave transmitted by the probe has a frequency band including the first and second frequencies.

  More preferably, the frequency band of the ultrasonic wave transmitted from the probe is determined, and a plurality of probes are used for the reception means to receive the corroded portion reflected wave and the end reflected wave.

  In another aspect of the present invention, there is provided a method for evaluating a defect of an underground structure for evaluating a degree of a defect caused by corrosion of a metal column existing in a soil portion. The method includes a step of transmitting a sound wave toward the soil side and a step of receiving a reflected wave. The reflected wave is a reflected wave from the end of the metal column on the soil side, is an end reflected wave having the first frequency, and is a reflected wave from the corroded portion of the metal column on the soil side. And a corroded portion reflected wave having a second frequency higher than the first frequency. The step of receiving the reflected wave includes the step of individually receiving the edge reflected wave and the corroded portion reflected wave. The defect evaluation method for the structure in the soil further includes a step of evaluating the degree of the defect due to corrosion based on the individually received end reflected wave and corroded part reflected wave.

  In yet another aspect of the present invention, the soil structure defect evaluation program transmits an ultrasonic wave having a predetermined frequency from the outside of the metal column to the soil side, and receives the reflected wave by the receiving means. Based on the reflected wave, the computer is caused to evaluate the degree of defects due to corrosion existing in the soil portion of the metal column. The reflected wave is a reflected wave from the end of the metal column on the soil side, is an end reflected wave having the first frequency, and is a reflected wave from the corroded portion of the metal column on the soil side. And a corroded portion reflected wave having a second frequency higher than the first frequency. The defect evaluation program for the underground structure causes the computer to receive the end reflected wave and the corroded portion reflected wave included in the reflected wave individually, and the received end reflected wave and And a step of evaluating the degree of defects due to corrosion based on the reflected wave of the corroded portion.

  According to the present invention, the reflected wave from the end of the metal column on the soil side, the reflected wave from the end portion having the first frequency and the reflected wave from the corroded portion of the metal column on the soil side, Since the corrosion portion reflected wave having the second frequency higher than the frequency of 1 is individually received, the degree of defects due to corrosion can be more accurately evaluated.

It is a schematic diagram which shows the example at the time of using the defect evaluation apparatus of an underground structure for the defect detection of a metal pillar like a panther mast. It is a block diagram which shows the structure of an ultrasonic flaw detector. It is a flowchart which shows the operation | movement procedure of an ultrasonic flaw detector. It is an example of the figure which shows the principal part of an experimental result. It is a flowchart which shows the processing operation | movement of the data analysis and evaluation of waveform data. It is a figure which shows the cross-sectional view of a corrosion part and an edge part, and the waveform data of the reflective echo corresponding to it. It is a flowchart which shows the operation | movement of the process of the detailed determination A in an analysis part.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing an example of a case where a defect evaluation apparatus for an underground structure according to the present invention is used to detect a defect of a metal column such as a panther mast. Referring to FIG. 1, a part of a metal column 31 such as a panther mast is embedded in soil, and is divided into a ground portion 34 and a soil portion 35 at a ground 33. The underground structure defect evaluation apparatus includes a probe 10 installed on the ground portion 34 of the metal column 31 via the contact medium 15 and an ultrasonic flaw detector 20 connected to the probe 10.

  The probe 10 enters and propagates an ultrasonic signal having a predetermined frequency to the soil side of the metal column 31 and corrodes in the soil. A reflected wave 12 (hereinafter also referred to as “reflected echo”) 12 is received. The ultrasonic flaw detector 20 determines and evaluates the degree of defects in the corroded portion 13 based on the waveform data corresponding to the reflected echo from the probe 10.

  In addition, it is preferable that the plate | board thickness of the metal pillar 31 is 6 mm or less.

  The ultrasonic waves used here are soil and concrete in contact with the outer surface in order to clearly receive the reflected echoes from the corroded portion 13 and the end portion 32, and the front and back surfaces such as irregularities caused by the corrosion generated on the inner surface. The influence of the pseudo echo caused by the shape is the least, and it is necessary to propagate at least so that it can be detected as a reflected echo from the end portion 32. For this reason, it is preferable to apply SH wave (Shear Horizontal Wave) among various ultrasonic modes for measurement. The SH wave is a wave whose particle motion is perpendicular to the traveling direction of the ultrasonic wave and vibrates in the horizontal direction with respect to the flaw detection surface (surface).

  FIG. 2 is a block diagram showing a configuration of the ultrasonic flaw detector 20. With reference to FIG. 2, the ultrasonic flaw detector 20 turns on the operation of the CPU 21 that controls the entire ultrasonic flaw detector 20, the interface 22 for connecting the CPU 21 to each component, and the ultrasonic flaw detector 20. The switch 23 to be turned off, the pulser 24 for supplying power to the probe 10, the receiver 25 for receiving the reflected echo detected by the probe 10, and the information of the reflected echo received by the receiver 25 are stored. A memory 26, an analysis unit 27 that performs data analysis using the waveform data of the reflected echoes from the corroded part 13 and the end part 32 received by the receiver 25, and a display 28 that displays a waveform such as the reflected echoes. Including.

  The receiver 25 includes a first reception filter 25a that receives a reflected echo having a first frequency, and a second reception filter 25b that receives a reflected echo having a higher frequency than the first. Thereby, the reflected echoes having the first and second frequencies can be individually received. The receiver 25 includes a switching unit 25c, and can selectively receive a reflected echo having the first or second frequency. The switching by the switching unit 25c may be switched manually or automatically. The receiver 25 operates as a receiving unit, and the switching unit 25c operates as a switching unit.

  Next, the operation of the ultrasonic flaw detector 20 will be described. FIG. 3 is a flowchart showing an operation procedure of the ultrasonic flaw detector 20. Referring to FIG. 3, the ultrasonic flaw detector 20 performs each process of pre-preparation, flaw detection preparation, flaw detection, data analysis / evaluation, and removal / completion.

  In advance preparation, the ultrasonic flaw detector 20 and the built-in system program are started, the distance to the end 32 of the panther mast (for example, about 2000 mm) is confirmed by a drawing or the like, and the ultrasonic flaw detector 20 should be used for measurement. A preliminary survey is performed by setting a measurement range, which is the length (step S11 in FIG. 3; the following steps are omitted). Next, the reference sensitivity is adjusted (S12), and the flaw detection sensitivity is adjusted (S13). In addition, the reference sensitivity is prepared, for example, by preparing a test piece in which a through hole having a diameter of 10 mm is formed in an iron plate having a thickness of 3 mm, and a predetermined distance from the through hole (a distance determined in consideration of a positional relationship in actual measurement) (For example, about 300 mm) The probe 10 is fixed to a position away. A reflected echo from the through hole is obtained, and the reflected echo is adjusted to a level of 80% on the display 28.

  In the flaw detection preparation process, first, a flaw detection surface pretreatment such as removal of deposits that obstruct the incidence of ultrasonic waves is performed (S14). Next, the position of the probe 10 is confirmed so that the probe 10 can be placed at the predetermined distance (for example, about 300 mm) from the ground 33 (S15). Thereafter, the contact medium 15 is applied to the attachment position of the probe 10 (S16).

  In the flaw detection process, measurement is started when the switch 23 is turned on, and for example, the panzer mast is flawed using the probe 10 that outputs a 350 kHz SH wave (S17).

  In the data analysis / evaluation process, data is collected by storing the reflected echo signals from the corroded portion 13 and the end portion 32 of the subsurface 33 as they are in the memory 26 as raw waveforms (S18), and the display 28 in real time. Data analysis is performed while displaying on the screen (S19). Based on the analysis result, the degree of defects due to corrosion is displayed as, for example, sound, mild, moderate, and severe, and evaluation / determination is performed (S20).

  In the removal / completion process, the probe 10 is removed from the panzer mast, the ultrasonic flaw detector 20 is removed (S21), the contact medium 15 is removed, and the process is terminated (S22).

  Next, the principle of the present invention will be described. FIG. 4 is an example of a diagram showing a main part of an experimental result obtained by the inventors of the present invention. Waveform data when the echoes having a frequency of 350 kHz are transmitted from the probe and reflected echoes from the corroded portion and the end portion at the ground are received at frequencies of 200 kHz and 500 kHz are shown. The horizontal axis represents the beam path from the probe, and the vertical axis represents the echo height of the reflected echo. (A) is waveform data when the reflected echo from the corroded part is received at a frequency of 200 kHz, and (B) is waveform data when the reflected echo from the corroded part is received at a frequency of 500 kHz. (C) is waveform data when a reflected echo from the end is received at a frequency of 200 kHz, and (D) is waveform data when a reflected echo from the end is received at a frequency of 500 kHz.

  Referring to (A) and (B), the shape of the waveform (the circled part) in the beam path for detecting the corroded part reflection echo is clearer in (B) than in (A). Since the echo height (peak value) is about twice as high, it can be seen that the echo height (peak value) is suitable for detecting data for analysis from the waveform data.

  That is, it can be seen that the frequency for receiving the waveform data of the corroded part reflection echo at the ground with high resolution is preferably 500 kHz rather than 200 kHz.

  Similarly, with reference to (C) and (D), the waveform shape (circled portion) in the beam path for detecting the end reflection echo is (C) rather than (D). Since the result is clear and the echo height (peak value) is about twice as high, it can be seen that it is suitable for detecting data for analysis from the waveform data.

  That is, it can be seen that the frequency for receiving the waveform data of the end reflection echo with high resolution is preferably 200 kHz rather than 500 kHz.

  As a result of the above, in the ultrasonic wave propagating through a metal column or the like, the ultrasonic wave having a high frequency has a short wavelength, so that it is easy to catch corrosion or the like but is also easily scattered or attenuated. On the other hand, since the ultrasonic wave with a low frequency has a long wavelength, it is due to the general property of the ultrasonic wave that it is difficult to catch corrosion or the like but is difficult to scatter or attenuate. Therefore, in order to receive a desired reflected echo with high resolution, the longer the ultrasonic wave propagation distance, the longer the ultrasonic wave propagation distance, the lower the frequency at which the receiver receives, It is preferable that the shorter the signal is, the higher the frequency is received by the receiver. Therefore, the end reflection echo has a long distance from the probe to the end, and is preferably received at a low frequency corresponding to the distance. On the other hand, since the distance from the probe to the corroded portion on the ground is short in the ground corroded portion reflection echo, it is preferably received at a high frequency corresponding to the distance.

  In view of the above principle, in this embodiment, by using a probe created so as to have a center frequency of, for example, 350 kHz and a frequency band of 200 to 500 kHz (hereinafter referred to as “frequency band”), for example, Reflected echoes from the corroded portion and the end portion at the ground can be received with high resolution at the first frequency (200 kHz) and the second frequency (500 kHz) that are received by the receiver. The center frequency and its frequency band are examples, and both the center frequency and its frequency band may be set arbitrarily. The center frequency is a frequency set when an ultrasonic wave having a specific frequency band is transmitted from the probe.

  However, there is a limit, that is, a definition, in the frequency band that the ultrasonic wave transmitted from one probe has. Accordingly, in the frequency band of the ultrasonic wave transmitted from one probe, both the corroded portion reflected echo and the edge reflected echo cannot be formed, that is, they cannot be received together. This case will be described later.

  Next, the data analysis / evaluation process in S18 to S20 will be described. FIG. 5 is a flowchart showing the operation of the evaluation / determination process (analysis procedure of the reflected echo waveform data) in the data analysis / evaluation process. This processing is performed by the receiver 25 and the analysis unit 27 under the control of the CPU 21 in FIG. Note that, based on S11 and S15 in FIG. 3, the first reception filter has a frequency of 200 kHz, and the second reception filter has a frequency of 500 kHz and receives reflected echoes from the edge portion and the corroded portion on the ground. Further, as described above, a probe having a center frequency of 350 kHz and a frequency band of 200 to 500 kHz is used.

  With reference to FIG. 2 and FIG. 5, an ultrasonic wave is first transmitted from the probe 10 (S201). Next, the switching unit 25c sets the receiver 25 so as to be received by the second reception filter 25b (S202). If a ground corroded portion reflected echo is recognized by the second receiving filter 25b (YES in S203), the waveform data of the ground corroded portion reflected echo is stored in the memory 26, and the receiver 25 is switched by the switching unit 25c. Is received by the first reception filter 25a (S204). When the waveform data of the end reflection echo is received by the first reception filter 25a (S205), the waveform data is stored in the memory 26, and the detailed determination A is executed (S301). Detailed determination A will be described later.

  If the corroded portion reflection echo is not recognized by the second reception filter 25b (NO in S203), the switching unit 25c is set so that the receiver 25 is received by the first reception filter 25a (S206). When the end reflection echo is recognized by the first reception filter 25a (YES in S207), the waveform data of the end reflection echo is stored in the memory 26, and the beam path length determines whether or not the reflection echo is from the correct end. Whether or not they match is examined (S208). If it matches the beam path to the end (YES in S208), it is determined as sound or minute corrosion (S209). If it does not match the beam path to the end (NO in S208), there may be a measurement error or the possibility of a special corrosion condition. Therefore, it is determined whether or not there is an input error in the flaw detection conditions (S210). It is determined that there is a possibility of an error or a special corrosion situation (S211), or after the input is corrected, the evaluation determination is restarted (S212). In addition, when no end reflection echo is recognized by the first reception filter 25a (NO in S207), there is a possibility of a measurement error or a special corrosion situation as in the case of NO in S208. It is determined whether or not there is a possibility of a measurement error or a special corrosion situation (S211). After the input is corrected, the evaluation determination is restarted (S212).

  Next, the detailed determination A in S301 in FIG. 5 will be described. FIG. 6 is an example of a diagram showing the relationship between the cross section (A) of the corroded portion 13 of the buried portion of the metal column 31 and the waveform (B) of the corroded portion reflected echo caused by the corrosion on the ground, It is an example of the figure which shows the relationship between the cross section (C) in the edge part 32 of the metal pillar 31 in the soil side, and the waveform (D) of the edge part reflection echo from the edge part 32. FIG. FIG. 7 is a flowchart showing the processing operation of the analysis unit in the detailed determination A in S301 of FIG.

  With reference to FIG. 6 and FIG. 7, in the detailed determination A, first, the peak value H1 of the waveform data of the corroded portion reflected echo stored in the memory is detected ((B), S311 in FIG. 6). . Next, in the same manner as the procedure for calculating the “rising angle coefficient θ” disclosed in Patent Document 1 (paragraph number 0040, FIG. 5C), using the peak value H1 in S311, the reflected part of the corroded area at the ground. The waveform data of the echo is normalized and the rising angle coefficient θ is calculated (S312). Note that the echo height of the corroded portion reflected echo detected after normalization in S312 is defined as K-EH% (S313). Next, the waveform data corresponding to the end reflection echo is normalized, the echo height of the end reflection echo detected after normalization is detected, and defined as T-EH% (S314). Note that the normalization in S314 is performed at the same ratio as when the ground corroded part echo is normalized in S312 as disclosed in Patent Document 1 (paragraph number 0046). Next, evaluation points are given using the angle coefficient θ calculated in S312 to S314, the echo height K-EH% of the corroded portion reflection echo, and the echo height T-EH% of the end portion reflection echo as parameters ( S315). The degree of defects is evaluated from the evaluation points given to the respective parameters (S316). Note that the echo height K-EH% of the corroded portion reflected echo at S313 and the echo height T-EH% of the end reflected echo at S314 are the echo heights adjusted as the reference sensitivity in S12 of FIG. Is the ratio of the echo height of reflected echoes from the corroded part and the edge part of the ground to the depth.

  Next, the evaluation of the degree of defects in S316 will be described. Table 1 below shows an example of an evaluation method of the degree of corrosion defects by the analysis unit, and is based on the evaluation method disclosed in Patent Document 1 (Table 1 in Paragraph No. 0052). In addition, the echo height K-EH% of the corroded part reflection echo in Table 1 is higher as the degree of corrosiveness is larger. Further, the echo height T-EH% of the end reflection echo is lower as the degree of ground corrosion is larger. This is due to the correlation between the echo height of the reflected echo from the corroded portion and the end portion at the ground, which is disclosed in Patent Document 1 (paragraph number 0044).

  Referring to Table 1, the analysis unit uses the ground corroded portion reflection echo and the end portion reflected echo, and uses the rising angle coefficient θ, the echo height K-EH% of the corroded portion reflected echo, and the edge. From the total of the respective evaluation points based on the echo height T-EH% of the partial reflection echo, the degree of defects due to ground corrosion is evaluated. For example, the degree of defects due to subsurface corrosion is evaluated in four stages, such as soundness, mildness, mediumness, and severity, from the lowest evaluation point.

  According to the above, the edge reflection echo having the frequency of 200 kHz that is the first frequency and the corroded reflection echo on the ground having the frequency of 500 kHz that is the second frequency higher than the first frequency are individually provided. In order to receive, the corroded part reflection echo and the edge reflection echo on the ground can be received with high resolution. Therefore, highly accurate evaluation can be performed based on each high-resolution waveform data.

  In the above embodiment, a case has been described in which the second reception filter receives a reflected echo having a frequency of 500 kHz (here, referred to as “frequency f1”) in order to receive a ground corroded portion reflected echo. However, the present invention is not limited to this, and a reflected echo having a desired frequency f2 (f2 <f1) may be received. The frequency f2 here is a frequency that satisfies the relational expression of f0 <f2 <f1 when the first reception filter receives a reflected echo having a frequency of 200 kHz (herein, “f0”). For example, a reflected echo having a frequency of 400 kHz may be received. By doing so, it is possible to receive reflected echoes from corrosion at the intermediate portion between the ground and the edge. Accordingly, the degree of corrosion defects in the intermediate portion can be evaluated by performing data analysis / evaluation using the echo height of the reflected echo having a frequency of 400 kHz.

  Next, another embodiment will be described. In this embodiment, as described in the above embodiment, a case will be described in which a single probe cannot receive a corroded portion reflection echo and an end portion reflection echo on the ground.

  The case described above is, for example, a case where the frequency at which the corroded portion reflected echo is received is 600 kHz and the frequency at which the end reflected echo is received is 100 kHz. Although one probe can transmit an ultrasonic wave having a frequency band of 200 to 500 kHz, there may be a case where an ultrasonic wave having a frequency band of 100 to 600 kHz cannot be transmitted. At this time, the ultrasonic wave transmitted from one probe cannot receive the corroded portion reflected echo and the end reflected echo on the ground.

  In view of the above, the frequency band including the frequency at which the corroded portion reflected echo is received and the frequency at which the end reflected echo is received is divided into a plurality of frequencies according to the probe used, and the corroded portion reflected at the surface. An ultrasonic wave having a different center frequency having a frequency band including a frequency for receiving the echo and the end reflection echo is transmitted using a plurality of probes. Moreover, the corroded part reflection echo and the edge reflection echo at the ground are received using a plurality of ultrasonic flaw detectors having a receiver corresponding to each probe. In this way, since it is possible to transmit ultrasonic waves suitable for receiving the eroded part reflection echo and the edge reflection echo at the subsurface, the erosion part reflection echo and the end reflection echo at the subsurface can be transmitted with high resolution. Can receive.

  The configuration of this embodiment is different from the above-described embodiment in that a plurality of probes that transmit different center frequencies and a plurality of ultrasonic flaw detectors having a receiver corresponding to each probe are used. That is the point. A specific configuration will be described later.

  Table 2 below shows an example of the relationship between the center frequency of the ultrasonic wave transmitted from the probe and the frequency band of the ultrasonic wave.

  Referring to Table 2, for example, in this embodiment, as a result of S11 and S15, in order to receive the edge reflection echo and the ground corrosion reflection echo with high resolution, the frequencies of 100 kHz and 600 kHz Suppose that it is known that the first and second receiving filters need to receive reflected echoes at frequencies of 100 kHz and 600 kHz.

  As a configuration in this embodiment, a probe C having a center frequency of 200 kHz and a frequency band of 100 to 300 kHz and an ultrasonic flaw detector C having a receiver C corresponding to the probe C are prepared. The receiver C receives reflected echoes having frequencies of 100 kHz and 300 kHz by the first and second reception filters. In addition, a probe D having a center frequency of 500 kHz and a frequency band of 300 to 600 kHz and an ultrasonic flaw detector D having a receiver D corresponding to the probe D are prepared. The receiver D receives reflected echoes having frequencies of 300 kHz and 600 kHz by the first and second reception filters. The operations of the probe C and the probe D and the operations of the ultrasonic flaw detector C and the ultrasonic flaw detector D are the same as those in the above embodiment.

  First, the probe C and the ultrasonic flaw detector C having the receiver C are applied to a defect evaluation apparatus for an underground structure. Next, an ultrasonic wave is transmitted from the probe C, and the end reflection echo in the reflection echo is received by the receiver C by the first reception filter in the frequency band of the ultrasonic wave. Next, the probe D and the ultrasonic flaw detector D having the receiver D are applied to a defect evaluation apparatus for an underground structure. Next, an ultrasonic wave is transmitted from the probe D, and the corroded portion reflected echo in the reflected echo is received by the receiver D by the second receiving filter in the frequency band of the ultrasonic wave.

  According to the above, two ultrasonic waves having a center frequency of 200 kHz and 500 kHz are transmitted, and depending on the frequency band each ultrasonic wave has, an end reflection echo having a frequency of 100 kHz and a subsurface corrosion having a frequency of 600 kHz Since the partial reflection echo is received separately, the corroded portion reflection echo and the end reflection echo on the ground can be received with high resolution.

  In the above embodiment, a case has been described in which ultrasonic waves having different center frequencies are transmitted using two probes in order to receive the edge reflection echo and the corroded portion reflection echo. Without limitation, three or more probes may be used. In the above embodiment, the probe C having a center frequency of 200 kHz and a frequency band of 100 to 300 kHz in order to receive an end reflection echo having a frequency of 100 kHz and a subsurface corrosion reflection echo having a frequency of 600 kHz. The probe D having the center frequency of 500 kHz and the frequency band of 300 to 600 kHz has been described. For example, the end reflection echo is received by the probe B having the center frequency of 100 kHz and the frequency band of 80 to 100 kHz. Then, the reflected echo on the ground is received by the probe D having a center frequency of 500 kHz and a frequency band of 300 to 600 kHz, and using the probe C having a center frequency of 200 kHz and a frequency band of 100 to 300 kHz. Even if it receives a reflection echo from corrosion at the middle between the edge and the edge There.

  In the above embodiment, a case has been described in which a plurality of ultrasonic flaw detectors having a plurality of probes and receivers corresponding to the probes are used. However, the present invention is not limited to this, and a plurality of probes are used. On the other hand, one ultrasonic flaw detector may be used. For example, for two probes having a center frequency of 200 kHz and 500 kHz, a first receiving filter that receives an end reflection echo having a frequency of 100 kHz and a corroded part reflection echo having a frequency of 600 kHz are received. An ultrasonic flaw detector having a receiver for switching and receiving the second reception filter by the switching unit is used.

  In the above embodiment, the case where the receiver receives the corroded portion reflected echo and the end reflected echo at the ground by the first and second receiving filters has been described. In a band between the frequency at which the corroded portion reflected echo is received and the frequency at which the end portion reflected echo is received, the receiver may receive the reflected echo having a desired frequency. By doing so, it is possible to evaluate the degree of corrosion defects at the intermediate portion between the edge and the edge.

  In addition, although the ultrasonic wave transmitted from the probe has been described for a case where it has a certain frequency band, the present invention is not limited to this, and there is no frequency band. May be an ultrasonic wave having a frequency corresponding to.

  In addition, you may enable it to set the ultrasonic wave transmitted from a probe to a desired frequency. By doing so, it is possible to receive a reflected echo from corrosion existing at a desired position between the ground and the edge.

  The receiver includes the first reception filter, the second reception filter, and the switching unit, and selectively receives the edge reflection echo and the corroded part reflection echo individually by switching the switching unit. As described, the receiver receives a first receiver that receives an end reflection echo having a first frequency, and a first receiver that receives a submerged corrosion reflection echo having a second frequency higher than the first. In the configuration in which the two receivers are separately provided, the end reflection echo and the ground corrosion reflection echo may be received individually and simultaneously.

  Although one embodiment of the present invention has been described with reference to the drawings, the present invention is not limited to the illustrated embodiment. Various modifications can be made to the illustrated embodiment within the same scope or equivalent scope as the present invention.

  DESCRIPTION OF SYMBOLS 10 Probe, 11 SH wave, 12 Reflected echo, 13 Corrosion part, 15 Contact medium, 20 Ultrasonic flaw detector, 21 CPU, 24 Pulser, 25 Receiver, 25a 1st receiving filter, 25b 2nd receiving filter, 25c Switching unit, 26 memory, 27 analysis unit, 28 display, 31 metal pillar, 32 end.

Claims (6)

A device for evaluating defects in soil structures that evaluates the degree of defects due to corrosion of metal columns present in the soil,
A probe that is attached to an outer portion of the metal pillar in the soil, transmits an ultrasonic wave having a predetermined frequency toward the soil side, and detects a reflected wave;
The ultrasonic waves are SH waves,
An ultrasonic flaw detector for receiving the reflected wave detected by the probe,
The reflected wave is
The reflected wave from the end of the metal column in the soil side, the end reflected wave having a first frequency according to the distance from the end of the soil side to the ultrasonic flaw detector,
A corroded portion that is a reflected wave from a corroded portion on the soil side of the metal column and has a second frequency higher than the first frequency according to a distance from the corroded portion on the soil side to the ultrasonic flaw detector. Including reflected waves,
The ultrasonic flaw detector is viewing contains a receiving means said receiving the corroded portions reflected wave and the end reflected waves separately,
A soil structure defect evaluation apparatus that evaluates the degree of defects due to corrosion based on the edge reflected waves and the corroded portion reflected waves individually received by the receiving means .   2. The underground structure defect evaluation apparatus according to claim 1, wherein the reception unit includes a switching unit that selectively receives the corroded portion reflected wave and the end portion reflected wave.   The subsurface structure defect evaluation apparatus according to claim 1, wherein the ultrasonic wave transmitted by the probe has a frequency band including the first and second frequencies. The frequency band of the ultrasonic wave transmitted from the probe is determined,
The said probe is a defect evaluation apparatus of the underground structure in any one of Claims 1-3 used in order for the said receiving means to receive the said corrosion part reflected wave and the said edge part reflected wave. A method for evaluating a defect in a soil structure for evaluating a degree of a defect caused by corrosion of a metal column existing in a soil part,
Transmitting the ultrasonic wave having a predetermined frequency from the outside portion of the metal column to the soil side,
The ultrasonic waves are SH waves,
Receiving the reflected wave,
The reflected wave is a reflected wave from an end of the metal column on the soil side, and an end reflected wave having a first frequency according to the distance from the end of the soil side to the ultrasonic flaw detector. And a reflected wave from the corroded portion on the soil side of the metal column, and has a second frequency higher than the first frequency according to the distance from the corroded portion on the soil side to the ultrasonic flaw detector. Including the corroded part reflected wave,
Receiving the reflected wave includes individually receiving the edge reflected wave and the corroded reflected wave;
Assessing the degree of defects due to corrosion based on the individually received end reflected waves and the corroded part reflected waves,
Defect evaluation method for underground structures. Corrosion existing in the soil portion of the metal column based on the reflected wave by transmitting an ultrasonic wave having a predetermined frequency from the soil outer portion of the metal column toward the soil side and receiving a reflected wave by the receiving means. A defect evaluation program for underground structures, which causes a computer to evaluate the degree of defects by
The ultrasonic waves are SH waves,
The reflected wave is a reflected wave from an end of the metal column on the soil side, and an end reflected wave having a first frequency according to the distance from the end of the soil side to the ultrasonic flaw detector. And a reflected wave from the corroded portion on the soil side of the metal column, and has a second frequency higher than the first frequency according to the distance from the corroded portion on the soil side to the ultrasonic flaw detector. Including the corroded part reflected wave,
The underground structure defect evaluation program is for a computer,
Causing the receiving means to individually receive the end portion reflected wave and the corroded portion reflected wave included in the reflected wave;
Performing the step of evaluating the degree of defects due to corrosion based on the individually received end reflected waves and the corroded portion reflected waves.
Defect evaluation program for underground structures.

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