JP7164953B2 - Non-destructive diagnosis method for protective fences - Google Patents

Description

Application of Article 30, Paragraph 2 of the Patent Law published by

TECHNICAL FIELD The present invention relates to a non-destructive diagnosis method for a protective fence installed on a road, in particular, non-destructive diagnosis of a pillar as a foundation and evaluation of its soundness.

As a protective fence on general roads and highways, it prevents vehicles that go in the wrong direction from deviating from the road, oncoming lanes, or sidewalks, and also minimizes injuries to vehicle occupants and damage to vehicles. There are safety fences for vehicles intended to restore the vehicle to the normal direction of travel, and fences for pedestrians and bicycles intended to prevent pedestrians and bicycles from falling or crossing recklessly. there is

These protective fences are installed by embedding and fixing steel pipe posts as foundations in soil or concrete, and then attaching protective materials such as guardrails to the parts of the posts that appear above the ground.

As described above, since the protective fence is a member that is installed by embedding the ends of the posts outdoors, the posts deteriorate over time according to the environment after installation. For example, at the ground part of the support (the boundary between the ground and the ground), corrosion progresses and deteriorates over time due to the presence of oxygen in the atmosphere, the retention of rainwater, and the effects of snow-melting agents. As the corrosion progresses, the strength of the pillars decreases, so it is necessary to inspect the degree of corrosion in the protective fence as necessary to confirm that the soundness of the protective fence is being sufficiently maintained and managed. However, in general, due to the large number of facilities, the current situation is that only visual inspections are carried out to confirm the corrosion state of the surface of the protective material and the surface of the pillars.

However, although it is possible to confirm the state of corrosion on the surface of the protective material and the surface of the pillar by visual inspection, it is not possible to grasp the extent to which corrosion has progressed inside.

In addition, due to poor construction, etc., the posts were not embedded as designed, and the embedded length (distance from the ground to the embedded tip) was insufficient. In some cases, it may bend, but it is not possible to grasp the state of such a support post inside the ground by visual inspection.

Therefore, conventionally, the ultrasonic method is used to grasp the aged deterioration (corrosion) and construction defects (the state of the posts inside the ground, such as insufficient penetration length and bending) of protective fences. In the case of the method, there are various requirements, such as the need for an engineer with advanced expertise to investigate, and the need to smoothen the surface with a file or the like so that the ultrasonic waves can easily enter. Considering the construction period, it is actually difficult to inspect a large number of fences using the ultrasonic method, and an inspection technology that can screen for aging deterioration and construction defects in a short period of time is desired.

Under such circumstances, the present inventor has developed an inspection technology (non-patent Documents 1 and 2), and an inspection technology (Patent Document 1) that instantly judges and diagnoses various types of deterioration from vibration characteristics obtained by hitting steel bars, steel pipes, and concrete including guardrails.

However, although these inspection technologies can perform inspections in a shorter period of time than the conventional ultrasonic method, they only evaluate deterioration over time (corrosion), and evaluate poor construction (insufficient penetration length). Therefore, it cannot be said that it is sufficient as an inspection technology for evaluating the soundness of protective fences.

Takashi Matsunaga et al., "Development of aging deterioration inspection technology for guardrail supports", 70th Annual Conference of the Japan Society of Civil Engineers, (September 2015), pp331-332 Takashi Matsunaga et al., "Development of aging deterioration inspection technology for guardrail supports 2", 71st Annual Conference of the Japan Society of Civil Engineers, (September 2016), pp1421-1422

WO2016/092869A1

Under the above background, the present invention provides a non-destroying protective fence that performs a screening inspection in a short time for the condition of the protective fence due to deterioration over time and poor construction, specifically corrosion, insufficient penetration length, bending, and restraint of the foundation. An object is to provide a diagnostic method.

The invention according to claim 1,
Based on the vibration characteristics obtained from the vibration waveform generated by the excitation of the guard fence support,
A nondestructive diagnosis method for a protective fence for nondestructively diagnosing the soundness of the protective fence,
Based on the natural vibration data from the vibration characteristics, corrosion in the support, lack of embedment length, bending, deterioration in rigidity or reduction in fixing force due to reduction in binding force of the base are evaluated,
Based on the shock elastic wave data from among the vibration characteristics, the time interval between the time when the excitation started and the time when the reflected wave, which is the shock elastic wave, was observed, and the time interval measured at the normal column Evaluate the penetration length, bend position and/or corrosion position in the strut by comparing
A non-destructive diagnosis method for a protective fence for diagnosing the soundness of the protective fence by evaluation based on the natural vibration and evaluation based on the impact elastic wave ,
Evaluation based on the data of the natural vibration,
a step of frequency analysis of the vibration waveform to obtain a frequency distribution;
a step of selecting the minimum peak frequency as an evaluation peak frequency from among the peak frequencies having an intensity exceeding a predetermined threshold value from the frequencies of the natural vibration peaks of the obtained frequency distribution;
comparing the selected rated peak frequency with the rated peak frequency in a guard fence in good condition;
and determining the soundness of the protective fence based on the result of the comparison .

The invention according to claim 2,
Based on the vibration characteristics obtained from the vibration waveform generated by the excitation of the guard fence support,
A nondestructive diagnosis method for a protective fence for nondestructively diagnosing the soundness of the protective fence,
Based on the natural vibration data from the vibration characteristics, corrosion in the support, lack of embedment length, bending, deterioration in rigidity or reduction in fixing force due to reduction in binding force of the base are evaluated,
Based on the shock elastic wave data from among the vibration characteristics, the time interval between the time when the excitation started and the time when the reflected wave, which is the shock elastic wave, was observed, and the time interval measured at the normal column Evaluate the penetration length, bend position and/or corrosion position in the strut by comparing
A non-destructive diagnosis method for a protective fence for diagnosing the soundness of the protective fence by evaluation based on the natural vibration and evaluation based on the impact elastic wave ,
Evaluation based on the data of the natural vibration,
The frequency distribution was obtained by analyzing the frequency of the vibration waveform generated by the excitation of the pillars of the protective fence, which was previously known to have no corrosion, insufficient penetration length, bending, or lowering of the binding force of the foundation. setting, as a reference value for determination, the minimum peak frequency among the peak frequencies having an intensity exceeding a predetermined threshold value from the frequencies of the natural vibration peaks of the obtained frequency distribution;
obtaining a frequency distribution by frequency-analyzing the vibration waveform generated by the excitation of the struts of the protective fence to be diagnosed;
a step of selecting the minimum peak frequency as an evaluation peak frequency from among the peak frequencies having an intensity exceeding a predetermined threshold value from the frequencies of the natural vibration peaks of the obtained frequency distribution;
a step of comparing the selected evaluation peak frequency with a reference value for the determination;
and determining the soundness of the protective fence based on the result of the comparison .

The invention according to claim 3,
Based on the vibration characteristics obtained from the vibration waveform generated by the excitation of the guard fence support,
A nondestructive diagnosis method for a protective fence for nondestructively diagnosing the soundness of the protective fence,
Based on the natural vibration data from the vibration characteristics, corrosion in the support, lack of embedment length, bending, deterioration in rigidity or reduction in fixing force due to reduction in binding force of the base are evaluated,
Based on the shock elastic wave data from among the vibration characteristics, the time interval between the time when the excitation started and the time when the reflected wave, which is the shock elastic wave, was observed, and the time interval measured at the normal column Evaluate the penetration length, bend position and/or corrosion position in the strut by comparing
A non-destructive diagnosis method for a protective fence for diagnosing the soundness of the protective fence by evaluation based on the natural vibration and evaluation based on the impact elastic wave ,
Evaluation based on the data of the natural vibration data,
a step of obtaining a vibration waveform in a longitudinal vibration mode of the support by arranging a sensor on the upper surface of the support and vibrating the upper surface by striking the support;
a step of frequency-analyzing the obtained vibration waveform to obtain a frequency distribution;
obtaining the natural frequency of the longitudinal vibration mode of the strut from the obtained frequency distribution;
determining the total length of the strut based on the determined natural frequency;
deducting the length of the portion exposed above the ground from the obtained total length of the support to determine the embedded length of the support .

The invention according to claim 4,
Based on the vibration characteristics obtained from the vibration waveform generated by the excitation of the guard fence support,
A nondestructive diagnosis method for a protective fence for nondestructively diagnosing the soundness of the protective fence,
Based on the natural vibration data from the vibration characteristics, corrosion in the support, lack of embedment length, bending, deterioration in rigidity or reduction in fixing force due to reduction in binding force of the base are evaluated,
Based on the shock elastic wave data from among the vibration characteristics, the time interval between the time when the excitation started and the time when the reflected wave, which is the shock elastic wave, was observed, and the time interval measured at the normal column Evaluate the penetration length, bend position and/or corrosion position in the strut by comparing
A non-destructive diagnosis method for a protective fence for diagnosing the soundness of the protective fence by evaluation based on the natural vibration and evaluation based on the impact elastic wave,
The evaluation based on the shock elastic wave data is
identifying a reflected wave from the vibration waveform;
a step of acquiring a time interval between a start time of excitation of the struts of the protective fence and a time of observation of reflected waves;
comparing the obtained time interval with the time interval in a healthy guard fence;
and determining the soundness of the protective fence based on the result of the comparison,
The step of acquiring the time interval between the start time of excitation of the pillar of the protective fence and the observation time of the reflected wave is the first step of the autocorrelation function obtained from the vibration waveform generated by the excitation of the pillar of the protective fence. A non-destructive diagnosis method for guard fences , characterized in that the step of acquiring the time interval from one peak .

The invention according to claim 5,
Based on the vibration characteristics obtained from the vibration waveform generated by the excitation of the guard fence support,
A nondestructive diagnosis method for a protective fence for nondestructively diagnosing the soundness of the protective fence,
Based on the natural vibration data from the vibration characteristics, corrosion in the support, lack of embedment length, bending, deterioration in rigidity or reduction in fixing force due to reduction in binding force of the base are evaluated,
Based on the shock elastic wave data from among the vibration characteristics, the time interval between the time when the excitation started and the time when the reflected wave, which is the shock elastic wave, was observed, and the time interval measured at the normal column Evaluate the penetration length, bend position and/or corrosion position in the strut by comparing
A non-destructive diagnosis method for a protective fence for diagnosing the soundness of the protective fence by evaluation based on the natural vibration and evaluation based on the impact elastic wave,
The evaluation based on the shock elastic wave data is
a step of identifying a reflected wave from the vibration waveform generated by the vibration applied to the strut part of the protective fence to be diagnosed;
acquiring a time interval between the excitation start time and the reflected wave observation time for the specified reflected wave;
identifying the position of the reflecting surface where the reflected wave was generated from the obtained time interval;
determining the soundness of the protective fence based on the identified position of the reflective surface;
The step of acquiring the time interval between the start time of excitation of the pillar of the protective fence and the observation time of the reflected wave is the first step of the autocorrelation function obtained from the vibration waveform generated by the excitation of the pillar of the protective fence. A non-destructive diagnosis method for guard fences , characterized in that the step of acquiring the time interval from one peak .

The invention according to claim 6,
Using one vibration waveform generated by excitation of the strut part of the protective fence,
6. The non-destructive diagnosis of the protective fence according to any one of claims 1 to 5, wherein the evaluation based on the data of the natural vibration and the evaluation based on the data of the impact elastic wave are performed. The method.

The invention according to claim 7,
Using the vibration waveform generated by the excitation of the struts of the protective fence, evaluation based on the data of the natural vibration is performed as a primary screening,
After that, for the protective fence that was determined to have a decrease in rigidity or a decrease in fixing force at the support in the primary screening,
Evaluation based on the data of the shock elastic wave is performed as a secondary screening by using the vibration waveform generated by the excitation of other parts of the support fence of the protective fence. 6. A non-destructive diagnosis method for a protective fence according to any one of 5.

The invention according to claim 8,
Evaluation based on the data of the natural vibration,
a step of frequency analysis of the vibration waveform to obtain a frequency distribution;
a step of selecting a peak frequency in a specific vibration mode from the obtained natural vibration peaks of the frequency distribution as an evaluation peak frequency;
comparing the selected rated peak frequency with a similarly obtained rated peak frequency for a guard fence in good condition;
2. A non-destructive diagnosis method for a protective fence according to claim 1 , further comprising the step of judging the soundness of said protective fence based on the result of the comparison.

The invention according to claim 9,
When acquiring the data of the natural vibration, a sensor is arranged on the side surface of the column near the ground, and the vibration waveform is obtained by striking from the vicinity of the sensor to vibrate, and the data of the natural vibration is obtained. 9. The non-destructive diagnosis method for protective fences according to any one of claims 1 to 8 , characterized in that the information is acquired.

The invention according to claim 10,
The evaluation based on the shock elastic wave data is
identifying a reflected wave from the vibration waveform;
a step of acquiring a time interval between a start time of excitation of the struts of the protective fence and a time of observation of reflected waves;
comparing the obtained time interval with the time interval in a healthy guard fence;
10. The nondestructive diagnosis method for a protective fence according to any one of claims 1 to 9 , further comprising a step of judging the soundness of the protective fence based on the result of the comparison. be.

The invention according to claim 11,
The evaluation based on the shock elastic wave data is
a step of identifying a reflected wave from the vibration waveform generated by the vibration applied to the strut part of the protective fence to be diagnosed;
acquiring a time interval between the excitation start time and the reflected wave observation time for the specified reflected wave;
identifying the position of the reflecting surface where the reflected wave was generated from the obtained time interval;
and determining the soundness of the protective fence based on the specified position of the reflecting surface. It is a destructive diagnostic method.

The invention according to claim 12,
The step of acquiring the time interval between the excitation start time of the pillar of the protective fence and the reflected wave observation time is the step of acquiring the time interval from the vibration waveform generated by the excitation of the pillar of the protective fence. The non-destructive diagnosis method for protective fences according to claim 10 or 11 , characterized in that:

The invention according to claim 13,
When acquiring the data of the impact elastic wave, a sensor is placed near the top of the column, and the vibration waveform is obtained by striking and vibrating from the vicinity of the sensor, and the data of the impact elastic wave is acquired. The non-destructive diagnosis method for protective fences according to any one of claims 1 to 12, characterized in that:

The invention according to claim 14,
A nondestructive diagnostic system for protective fences used in the nondestructive diagnostic method for protective fences according to any one of claims 1 to 13,
a vibrating means for vibrating the pillars of the protective fence;
vibration characteristic acquisition means for acquiring vibration characteristics from the vibration waveform generated by the excitation;
A first evaluation of deterioration in rigidity or reduction in fixing force due to corrosion, insufficient embedment length, bending, and reduction in binding force of the base portion in the support portion based on the natural vibration data from among the vibration characteristics. a means of evaluation;
second evaluation means for evaluating the penetration length, bending position, and corrosion position in the support column based on the data of the impact elastic wave selected from the vibration characteristics;
A non-destructive diagnostic system for a protective fence, characterized by comprising diagnostic means for diagnosing soundness of the protective fence based on evaluation based on the first evaluation means and the second evaluation means.

The invention according to claim 15,
The first evaluation means is
a step of frequency analysis of the vibration waveform to obtain a frequency distribution;
a step of selecting the minimum peak frequency as an evaluation peak frequency from among the peak frequencies having an intensity exceeding a predetermined threshold value from the frequencies of the natural vibration peaks of the obtained frequency distribution;
comparing the selected rated peak frequency with the rated peak frequency in a guard fence in good condition;
15. The non-destructive diagnostic system for protective fences according to claim 14, wherein the step of judging the soundness of said protective fences is sequentially executed based on the result of the comparison. .

The invention according to claim 16,
The first evaluation means is
The frequency distribution was obtained by analyzing the frequency of the vibration waveform generated by the excitation of the pillars of the protective fence, which was previously known to have no corrosion, insufficient penetration length, bending, or lowering of the binding force of the foundation. setting, as a reference value for determination, the minimum peak frequency among the peak frequencies having an intensity exceeding a predetermined threshold value from the frequencies of the natural vibration peaks of the obtained frequency distribution;
obtaining a frequency distribution by frequency-analyzing the vibration waveform generated by the excitation of the struts of the protective fence to be diagnosed;
a step of selecting the minimum peak frequency as an evaluation peak frequency from among the peak frequencies having an intensity exceeding a predetermined threshold value from the frequencies of the natural vibration peaks of the obtained frequency distribution;
comparing the selected evaluation peak frequency with the reference value;
15. The non-destructive diagnostic system for protective fences according to claim 14, wherein the step of judging the soundness of said protective fences is sequentially executed based on the result of the comparison. .

The invention according to claim 17,
The first evaluation means is
a step of frequency analysis of the vibration waveform to obtain a frequency distribution;
a step of selecting a peak frequency in a specific vibration mode from the obtained natural vibration peaks of the frequency distribution as an evaluation peak frequency;
comparing the selected rated peak frequency with a similarly obtained rated peak frequency for a guard fence in good condition;
15. The non-destructive diagnostic system for protective fences according to claim 14, wherein the step of judging the soundness of said protective fences is sequentially executed based on the result of the comparison. .

The invention according to claim 18,
The first evaluation means is
obtaining a vibration waveform by causing the strut to vibrate in a longitudinal vibration mode with the vibrating means;
a step of frequency-analyzing the obtained vibration waveform to obtain a frequency distribution;
obtaining the natural frequency of the longitudinal vibration mode from the obtained frequency distribution;
obtaining the total length of the strut based on the obtained natural frequency of the longitudinal vibration mode;
15. The protective fence according to claim 14, further comprising a step of calculating the embedded length of the support by subtracting the length of the portion exposed above the ground from the obtained total length of the support. It is a non-destructive diagnostic system.

The invention according to claim 19,
The second evaluation means is
identifying a reflected wave from the vibration waveform;
a step of acquiring a time interval between a start time of excitation of the struts of the protective fence and a time of observation of reflected waves;
comparing the obtained time interval with the time interval in a healthy guard fence;
19. The method according to any one of claims 14 to 18, characterized in that the step of judging the soundness of the protective fence based on the result of the comparison is sequentially executed. It is a non-destructive diagnostic system for protective fences.

The invention according to claim 20,
The second determination means is
a step of identifying a reflected wave from the vibration waveform generated by the vibration applied to the strut part of the protective fence to be diagnosed;
acquiring a time interval between the excitation start time and the reflected wave observation time for the specified reflected wave;
identifying the position of the reflecting surface where the reflected wave was generated from the obtained time interval;
and determining the soundness of the protective fence based on the specified position of the reflecting surface. It is a non-destructive diagnosis system for the protective fence described in the item.

The invention according to claim 21,
A non-destructive diagnostic device for use in implementing the non-destructive diagnostic system for protective fences according to any one of claims 14 to 20,
a hammer that strikes the posts of the protective fence to generate vibration due to excitation;
a sensor that detects the generated vibration as a signal;
a preamplifier that amplifies the detected signal;
a digital oscilloscope that converts the amplified signal to digital and displays it as a vibration waveform;
a personal computer that diagnoses the soundness of the protective fence based on the vibration waveform,
The personal computer stores a program for converting the vibration waveform into natural vibration and impact elastic wave data and diagnosing soundness of the protective fence.

The invention according to claim 22,
22. A non-destructive diagnostic apparatus according to claim 21, wherein said sensor is an AE sensor.

According to the present invention, a non-destructive diagnosis method for protective fences that screens and inspects the state of protective fences due to aging deterioration and poor construction, specifically corrosion, insufficient penetration length, bending, and restraint of foundations in a short time. can provide.

It is a figure explaining the relationship between the installation position of a sensor and a hitting position in one embodiment of the present invention. It is a figure which shows an example of the vibration waveform obtained in one embodiment of this invention. It is a figure which shows an example of the frequency distribution obtained in one embodiment of the present invention. FIG. 4 is a diagram showing an example of the relationship between corrosion, insufficient penetration length, and evaluation peak frequency in one embodiment of the present invention. FIG. 4 is a diagram showing each evaluation peak frequency of a plurality of struts whose soundness has been confirmed in advance; FIG. 4 is a diagram showing an example in which the time interval between the excitation start time and the reflected wave observation time is directly acquired from the vibration waveform in one embodiment of the present invention; FIG. 4 is a diagram showing an example of obtaining the time interval between the excitation start time and the reflected wave observation time from the first peak of the autocorrelation function in one embodiment of the present invention; FIG. 10 is a diagram showing an example of vibration waveforms obtained from a sound column; FIG. 10 is a diagram showing an example of a vibration waveform obtained for a post with insufficient penetration length; FIG. 5 is a diagram showing the relationship between the natural frequency of the longitudinal vibration mode of the strut and the total length of the strut; FIG. 4 is a diagram showing measurement results of natural vibrations in longitudinal vibration modes of three types of struts; FIG. 4 is a diagram comparing experimental values of the natural frequency of a longitudinal vibration mode with theoretical values. 1 is a diagram showing the configuration of a non-destructive diagnosis apparatus according to one embodiment of the present invention; FIG.

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below based on embodiments.

[1] Circumstances leading to the present invention First, the circumstances leading to the present invention will be described.

In the course of earnestly studying how to solve the above problems, the inventors of the present invention have found that among various vibration characteristics obtained based on vibration waveforms obtained by striking (exciting) the strut, "natural vibration" and "impact vibration" are selected. Focusing on "elastic waves", as a result of examination, these are closely related to the state of protective fences due to deterioration over time and poor construction, specifically corrosion, insufficient penetration length, bending, and binding force of the foundation. , by appropriately analyzing these two parameters, it was found that they can be screened in a short period of time and the soundness of the guard fence can be diagnosed non-destructively.

In other words, with respect to "natural vibration", if corrosion progresses, if the penetration length is insufficient, if there is bending, if there is a decrease in the binding force of the foundation, the rigidity of the column may decrease or fixation may occur. Since the force is reduced and the natural vibration is lower than that of a healthy post, knowing the shift of this natural vibration to a low frequency can prevent corrosion of the protective fence, insufficient penetration length, bending, and binding force of the foundation. It is possible to evaluate the decrease in rigidity and the decrease in fixation force associated with the decrease in

As for the "shock elastic wave", if there is insufficient penetration, bending, or corrosion, the distance from the excitation point is short, so the time when the excitation started and the reflected wave, which is the impact elastic wave, is observed, the time interval is shorter than the time interval measured in a normal strut. Therefore, by knowing this time interval, it is possible to obtain positional information regarding insufficient penetration, bending, and corrosion.

As described above, according to the present invention, the state of the protective fence due to deterioration over time and poor construction, specifically corrosion and insufficient penetration length, can be evaluated based on the data of the natural vibration and the data of the impact elastic wave. , bends, and deterioration of binding force of the foundation can be screened in a short time to diagnose the soundness of the protective fence in a non-destructive manner.

Specifically, for example, if corrosion is progressing at the same time as insufficient penetration length, it will be judged as "bad" in the evaluation by natural vibration, and in the subsequent evaluation by impact elastic waves, if the corrosion is significant, reflection due to corrosion will occur. waves are observed. Since this result indicates that a defect has occurred near the ground, it can be determined that the support column needs to be replaced.

On the other hand, if the corrosion has not progressed, the impact elastic wave data will show the reflected wave at the end of the column. If the length is not the specified length, it can be determined that the penetration length is insufficient.

In some cases, the reflected wave at the end of the column is not observed. It is diagnosed that the strut needs to be replaced immediately.

In this way, by comprehensively evaluating data based on natural vibration data and impact elastic wave data, it is possible to diagnose the soundness of protective fences, so appropriate countermeasures can be formulated according to the diagnosis results. can do.

Specifically, if corrosion occurs but its progress is still small, measures such as painting may be planned to slow down the progress of corrosion.

On the other hand, if the progress of corrosion is large, it is necessary to pull out the post, remove it, and replace it. If the pulling method of inserting the pillar and pulling out the pillar is selected, there is a risk that the pillar will be damaged on the way due to the cross-sectional defect of the pillar part. However, in the present invention, since the progress of corrosion is quantitatively diagnosed in advance, a dedicated extraction method adapted to the progress can be adopted to pull out and replace the strut without damaging it.

In addition, as described above, the soundness of the pillar was evaluated by the "natural vibration" in the past, but the judgment based only on the "natural vibration" resulted in corrosion, insufficient penetration, bending, and foundation. It was difficult to identify the decrease in the binding force of the restraint, and in order to identify these, it was necessary to conduct additional investigations using visual confirmation and ultrasonic methods, which was not efficient.

[2] Embodiment of the Present Invention Next, a method for diagnosing a protective fence according to an embodiment of the present invention will be described in detail with specific examples.

In this embodiment, as described above, the soundness of the protective fence is diagnosed non-destructively based on the vibration characteristics obtained from the vibration waveform generated by the excitation of the struts of the protective fence.

1. Acquisition of vibration waveform First, while the sensor is in contact with the support to be diagnosed with a force that holds it lightly, the surface of the support is hit (excited) with a hammer or the like, and the vibration generated A vibration waveform is acquired by a sensor.

At this time, for the installation position of the sensor and the hitting position, an appropriate pattern is selected from FIGS. In FIG. 1, 1 is a sensor, 6 is a hammer, 11 is a protective fence (guard rail), and 12 is a support.

Fig. 1(a) shows a pattern in which a sensor is installed on the side surface of the pillar near the ground, and a blow is applied in the vicinity of the sensor. can do.

Fig. 1(b) shows a pattern in which a sensor is installed at the top of the column and the impact is applied from the top of the head. can.

Fig. 1(c) shows a pattern in which a sensor is installed on the side surface near the top of the head, avoiding the cap attached to the top of the post, and a blow is applied from the top of the head. It is possible to more effectively detect changes in the "shock elastic wave" that accompany changes in length.

Fig. 1 (d) is another pattern of Fig. 1 (c), in which the sensor is installed on the side near the top of the head avoiding the cap attached to the top of the post, and the impact is applied from the side near the top of the head. It's a pattern. As a result, similar to the pattern of FIG. 1(c), the effect of the cap can be reduced, and changes in the "impact elastic wave" accompanying changes in the penetration length can be detected more effectively.

In this embodiment, as the hammer 6, a test hammer that is generally used for hammering inspection, is light in weight, and is convenient to carry is preferably used. Any hammer other than the hammer, such as an iron hammer, which can vibrate the target and obtain the vibration, may be used instead of the test hammer.

As the sensor 1, it is preferable to use an AE (Acoustic Emission) sensor from the viewpoint of obtaining the vibration of the struck strut with high accuracy. may be used, and the impact sound may be acquired with a microphone.

An example of the obtained vibration waveform is shown in FIG. In FIG. 2, the horizontal axis is the elapsed time (Time (ms)) from the start of excitation, and the vertical axis is the amplitude (Amplitude (mV)). From FIG. 2, it can be seen that the amplitude is attenuated with the lapse of time and sufficiently attenuated in about 60 ms.

2. Evaluation of natural vibration Next, frequency analysis is performed on the obtained vibration waveform to obtain a frequency distribution. Among them, the minimum (lowest frequency side) peak frequency is selected as the evaluation peak frequency. A peak frequency in a specific vibration mode may be selected as the evaluation peak frequency from the natural vibration peaks of the obtained frequency distribution.

An example of the frequency distribution obtained is shown in FIG. In FIG. 3, the horizontal axis is frequency (Frequency (Hz)), and the vertical axis is vibration intensity (Magnitude). In FIG. 3, of the two natural vibration peaks exceeding the threshold (generally set to "0.5"), the minimum peak frequency of 2641 Hz is adopted as the evaluation peak frequency.

This evaluation peak frequency shifts from the sound evaluation peak frequency to the lower wavelength side due to deterioration of rigidity or fixing force due to corrosion, insufficient penetration length, bending, and reduction of binding force of the foundation. Therefore, by knowing the shift of the evaluation peak frequency to a lower frequency, it is possible to evaluate the deterioration of the rigidity or the fixing force due to the corrosion of the protective fence, the penetration length, bending, and the reduction of the binding force of the foundation. can do.

An example of these relationships is shown in FIG. In FIG. 4, the horizontal axis is the frequency (Hz), the vertical axis is the magnitude, the solid line is the data obtained from the healthy support, the dashed line is the data obtained from the insufficient penetration length of the support, and the one-dot chain line is the data obtained from the corroded support. As shown in FIG. 4, the evaluated peak frequencies are different for each strut, and the evaluated peak frequency decreases in the order of sound struts, insufficiently embedded struts, and corroded struts.

Therefore, by setting a predetermined frequency (3300 Hz in FIG. 4) as a reference value in advance, it is possible to determine whether or not the strut is sound based on this evaluation peak frequency.

This reference value is the evaluation peak frequency obtained from data on the natural vibration measured for multiple protective fences that are known in advance to have no corrosion, insufficient penetration, bending, or lowering of the binding force of the foundation. is appropriately set based on

In general, as shown in FIG. 4, a corroded post appears lower than a post with insufficient penetration length (the same applies to a post with a bend). By setting the value between the pillar with insufficient penetration length or bending and the pillar with corrosion, the pillar with insufficient penetration length or bending and the pillar with corrosion. However, the amount of decrease varies depending on the degree of insufficient penetration, bending, and corrosion, and when both insufficient penetration, bending, and corrosion occur at the same time. Therefore, it is not easy to distinguish between insufficient penetration length, bending, and corrosion based only on the second reference value.

As a specific example, FIG. 5 shows 43 pillars whose soundness has been diagnosed in advance (pillar numbers 1 to 3 are corroded pillars, 4 to 14 are pillars with insufficient penetration length or bending, Reference numerals 15 to 43 indicate each evaluation peak frequency obtained under the conditions shown in FIG. In FIG. 5, the horizontal axis is the column number, and the vertical axis is the evaluation peak frequency (Hz).

From FIG. 5, it can be seen that the unhealthy struts 1 to 14 and the healthy struts 15 to 43 can be clearly distinguished across the reference value (3300 Hz). On the other hand, looking at the posts with corrosion 1 to 3 and the posts with insufficient penetration length or bending in 4 to 14, the evaluation peak frequency was high for the posts with corrosion 1 and 2. Although it is clearly low, the evaluation peak frequency of the 3 corroded pillars is quite close to the 4 to 14 pillars with insufficient penetration length and bending. It can be seen that there is a risk of being diagnosed as having insufficient penetration length or bending instead of being diagnosed.

3. Evaluation of Shock Elastic Wave Therefore, in the evaluation of the natural vibration described above, only the evaluation of whether or not it is sound is performed based on the reference value (primary screening). It is preferable to evaluate the penetration length, bend position, and corrosion position (secondary screening) for the posts evaluated as not.

In this way, by selecting the majority of sound pillars in the primary screening and performing secondary screening only on the pillars evaluated as unsound in the primary screening, it is possible to efficiently diagnose the protective fence. .

Specifically, first, the column is hit to apply vibration, and from the obtained vibration waveform, the reflected wave, which is the impact elastic wave from the end or corroded surface, is identified, and then the excitation start time and the reflected wave Get the time interval from the observation time.

In the above description, the term "corroded surface" refers to a cross section having a cross-sectional defect due to corrosion, and when the cross-sectional defect is significant, reflected waves from the surface are observed.

The reason why the reflected wave from the corroded surface is specified is that if the reflected wave is observed at the ground level, it can be evaluated that cross-sectional loss has progressed and significant corrosion has occurred at the ground level. be.

There are two ways to obtain the time interval, one is to obtain it directly from the vibration waveform and the other is to obtain the first peak of the autocorrelation function. In the case of two round trips, it is preferable to use the autocorrelation function because it is possible to obtain a more accurate time interval.

FIG. 6 shows an example of the time interval obtained directly from the vibration waveform of a 1-m-long guardrail post, and FIG. 7 shows an example of the time interval obtained from the first peak of the autocorrelation function. 6 and 7, the horizontal axis is time (Time (10-3 s)), and the vertical axis is amplitude (au) in FIG. 9 and autocorrelation function strength (au) in FIG.

At this time, if the post is insufficiently embedded, bent, or corroded, the time interval until the reflected wave observation time is shortened. occurrence can be adequately identified.

Specifically, first, a vibration waveform is obtained for a sound column that has been confirmed to be in a sound state in advance.

FIG. 8 shows an example of a vibration waveform obtained for a sound column struck under the conditions shown in FIG. 1(b). In FIG. 8, the horizontal axis is time (Time (10-3s)) and the vertical axis is Amplitude (au). The peak surrounded by the dashed ellipse is the peak of the reflected wave, and the peak before the peak of the reflected wave is the peak of the elastic wave returning in the circumferential direction of the column, and is excluded from evaluation. .

From FIG. 8, it can be seen that in the case of a healthy post with a sufficient penetration length, a reflected wave is observed at a point of about 0.88 ms after impact.

Next, the vibration waveform is acquired for the strut that has been confirmed in advance to have an insufficient penetration length.

FIG. 9 shows an example of a vibration waveform obtained from a post with an insufficient penetration length hit under the conditions shown in FIG. 1(b). 8, in FIG. 9, the horizontal axis is time (Time (10-3 s)) and the vertical axis is Amplitude (a.u.). The peak surrounded by the dashed ellipse is the peak of the reflected wave, and the peak before the peak of the reflected wave is the peak of the elastic wave returning in the circumferential direction of the column, and is excluded from evaluation. .

From FIG. 9, it can be seen that in the case of the post with insufficient penetration length, the reflected wave was observed at a point of about 0.55 ms after impact.

From the results of FIGS. 8 and 9, it can be seen that reflected waves are observed in a shorter period of time in the post with insufficient penetration length than in the sound post with sufficient penetration length. Therefore, by knowing the time interval up to the observation time of this reflected wave, it is possible to appropriately know the lack of penetration length of the strut.

In the above description, "Evaluation of natural vibration" is defined as "primary screening" and "Evaluation of impact elastic wave" is defined as "secondary screening". However, the evaluation may be performed simultaneously based on one vibration waveform obtained by specifying the installation position of the sensor and the hitting position.

Depending on the protective fence, there are cases where both corrosion and insufficient embedment length have occurred in the pillars. judgment.

4. Quantitative Evaluation of Embedded Length In the present embodiment, the embedded length can be quantitatively evaluated based on the natural frequency of the longitudinal vibration mode of the strut.

That is, the longitudinal vibration mode is a vibration mode in which the strut repeats expansion and contraction in the axial direction of the strut. By measuring the number f, the total length of the strut can be known. By subtracting the length of the portion exposed above the ground from the total length, the embedded length can be quantitatively evaluated.

Specifically, the natural frequency f (Hz) of the longitudinal vibration mode can be obtained by Equation 1 shown below. However, in Equation 1, L is the length of the strut (m), E is the Young's modulus (N/m2), ρ is the density (kg/m3), and λ is a dimensionless constant determined by the boundary conditions and the vibration mode. (eigenvalue).

FIG. 10 shows the relationship between the length L of the strut and the natural frequency f of the longitudinal vibration mode obtained based on Equation 1 above. In FIG. 10, the horizontal axis is the total length of the strut (m), the vertical axis is the frequency (Hz) in the primary longitudinal vibration mode, and the theoretical values are indicated by solid lines.

Next, as a concrete support, using an underground guardrail (Type A, outer diameter of about 140 mm), the length at the ground is 700 mm, and the support 1 to the embedded length shown in Table 1. 3 specimens were produced, and three kinds of vibration waveforms were obtained by striking under the conditions shown in FIG. Table 1 also shows the ratio of the embedded length to the designed embedded length (1650 mm).

FIG. 11 shows the frequency distribution acquired from the obtained vibration waveform. In each frequency distribution shown in FIG. 11, the frequency peak appearing on the lowest frequency side (the part surrounded by the dashed circle) is the natural vibration peak of the primary mode of longitudinal vibration, and this frequency is the natural frequency of the primary mode. is f. From FIG. 11, it can be seen that the frequency peak (natural frequency f of the primary mode) shifts to the high frequency side as the penetration length becomes shorter.

Next, when the results were plotted on the curve of the theoretical values shown in FIG. 10 based on the natural frequency f of the primary mode of each strut and the total length of the strut, the experimental values were compared to the theoretical values as shown in FIG. It was confirmed that the penetration length could be quantitatively evaluated non-destructively.

That is, it can be seen from FIG. 12 that the natural frequency f becomes higher as the total length of the strut becomes shorter. After obtaining the total length of the pillar, subtracting the above-ground length, the embedded length can be quantitatively evaluated non-destructively.

5. Non-destructive diagnosis system The non-destructive diagnosis of the protective fence described above consists of a vibrating means for vibrating the struts of the protective fence, a vibration characteristic acquisition means for acquiring vibration characteristics from the vibration waveform generated by the vibration, and a vibration A first judgment means for judging occurrence of corrosion or insufficient penetration length in the strut part based on the natural vibration among the characteristics, and judging insufficient penetration length in the strut part based on the impact elastic wave among the vibration characteristics. and a diagnosis for diagnosing the soundness of the protective fence by evaluating the occurrence of corrosion and insufficient penetration length in the pillars based on the results of the first and second determination means. This can be done by constructing a non-destructive diagnostic system for guardrails comprising means.

Specifically, in the judgment means for judging the occurrence of corrosion or insufficient penetration length in the pillars, and the judgment means for judging the insufficient penetration length, the above-described steps are sequentially executed. This can be done by configuring a destructive diagnosis system.

6. Nondestructive Diagnosis Apparatus As a nondestructive diagnosis apparatus provided with such a nondestructive diagnosis system for protective fences, for example, a nondestructive diagnosis apparatus as shown in FIG. 13 can be cited.

In FIG. 13, 1 is a sensor (AE sensor) that detects vibration as a signal, 2 is a preamplifier that amplifies the signal detected by the sensor, 3 is a digital oscilloscope that converts the amplified signal into a digital signal and displays it as a vibration waveform. 4 is a personal computer (PC) storing a program for converting vibration waveforms into "natural vibration" and "impact elastic wave" data and comprehensively evaluating aging deterioration and construction failures of protective fences.

By using the non-destructive diagnosis device having such a configuration and performing processing according to the above method, the diagnosis of the protective fence can be performed in a short time with high accuracy.

7. Effect of the present embodiment As described above, according to the present embodiment, pre-diagnosis work such as conventional methods using ultrasonic waves for evaluating the embedded length of the support can be performed. (pre-processing such as smoothing the surface of the diagnosis target) and a large amount of time for diagnosis are unnecessary, so it is possible to greatly reduce the diagnosis time and screen a large number of guard fences in a short time with high accuracy. be able to. In addition, unlike the conventional hammering system, it is possible to evaluate the penetration length at the same time.

As a result, according to the present embodiment, it is possible to significantly reduce the cost and labor and efficiently maintain and manage the protective fence.

In the above description, the struts of the protective fence have been described, but the same can be applied to the diagnosis of lighting tower struts and small sign struts made of the same steel pipe.

Although the present invention has been described above based on the embodiments, the present invention is not limited to the above embodiments. Various modifications can be made to the above embodiment within the same and equivalent scope of the present invention.

1 sensor (AE sensor)
2 Preamplifier 3 Digital oscilloscope 4 PC
6 Hammer 11 Protective fence 12 Strut part

Claims (22)

A non-destructive diagnosis method for a protective fence for non-destructively diagnosing the soundness of the protective fence based on the vibration characteristics obtained from the vibration waveform generated by the excitation of the struts of the protective fence,
Based on the natural vibration data from the vibration characteristics, corrosion in the support, lack of embedment length, bending, deterioration in rigidity or reduction in fixing force due to reduction in binding force of the base are evaluated,
Based on the shock elastic wave data from among the vibration characteristics, the time interval between the time when the excitation started and the time when the reflected wave, which is the shock elastic wave, was observed, and the time interval measured at the normal column Evaluate the penetration length, bend position and/or corrosion position in the strut by comparing
A non-destructive diagnosis method for a protective fence for diagnosing the soundness of the protective fence by evaluation based on the natural vibration and evaluation based on the impact elastic wave,
Evaluation based on the data of the natural vibration,
a step of frequency analysis of the vibration waveform to obtain a frequency distribution;
a step of selecting the minimum peak frequency as an evaluation peak frequency from among the peak frequencies having an intensity exceeding a predetermined threshold value from the frequencies of the natural vibration peaks of the obtained frequency distribution;
comparing the selected rated peak frequency with the rated peak frequency in a guard fence in good condition;
and determining the soundness of the protective fence based on the result of the comparison. A non-destructive diagnosis method for a protective fence for non-destructively diagnosing the soundness of the protective fence based on the vibration characteristics obtained from the vibration waveform generated by the excitation of the struts of the protective fence,
Based on the natural vibration data from the vibration characteristics, corrosion in the support, lack of embedment length, bending, deterioration in rigidity or reduction in fixing force due to reduction in binding force of the base are evaluated,
Based on the shock elastic wave data from among the vibration characteristics, the time interval between the time when the excitation started and the time when the reflected wave, which is the shock elastic wave, was observed, and the time interval measured at the normal column Evaluate the penetration length, bend position and/or corrosion position in the strut by comparing
A non-destructive diagnosis method for a protective fence for diagnosing the soundness of the protective fence by evaluation based on the natural vibration and evaluation based on the impact elastic wave,
Evaluation based on the data of the natural vibration,
The frequency distribution was obtained by analyzing the frequency of the vibration waveform generated by the excitation of the pillars of the protective fence, which was previously known to have no corrosion, insufficient penetration length, bending, or lowering of the binding force of the foundation. setting, as a reference value for determination, the minimum peak frequency among the peak frequencies having an intensity exceeding a predetermined threshold value from the frequencies of the natural vibration peaks of the obtained frequency distribution;
obtaining a frequency distribution by frequency-analyzing the vibration waveform generated by the excitation of the struts of the protective fence to be diagnosed;
a step of selecting the minimum peak frequency as an evaluation peak frequency from among the peak frequencies having an intensity exceeding a predetermined threshold value from the frequencies of the natural vibration peaks of the obtained frequency distribution;
a step of comparing the selected evaluation peak frequency with a reference value for the determination;
and determining the soundness of the protective fence based on the result of the comparison. A non-destructive diagnosis method for a protective fence for non-destructively diagnosing the soundness of the protective fence based on the vibration characteristics obtained from the vibration waveform generated by the excitation of the struts of the protective fence,
Based on the natural vibration data from the vibration characteristics, corrosion in the support, lack of embedment length, bending, deterioration in rigidity or reduction in fixing force due to reduction in binding force of the base are evaluated,
Based on the shock elastic wave data from among the vibration characteristics, the time interval between the time when the excitation started and the time when the reflected wave, which is the shock elastic wave, was observed, and the time interval measured at the normal column Evaluate the penetration length, bend position and/or corrosion position in the strut by comparing
A non-destructive diagnosis method for a protective fence for diagnosing the soundness of the protective fence by evaluation based on the natural vibration and evaluation based on the impact elastic wave,
Evaluation based on the data of the natural vibration data,
a step of obtaining a vibration waveform in a longitudinal vibration mode of the support by arranging a sensor on the upper surface of the support and vibrating the upper surface by striking the support;
a step of frequency-analyzing the obtained vibration waveform to obtain a frequency distribution;
obtaining the natural frequency of the longitudinal vibration mode of the strut from the obtained frequency distribution;
determining the total length of the strut based on the determined natural frequency;
and deducting the length of the portion exposed above the ground from the obtained total length of the support to determine the embedded length of the support. A non-destructive diagnosis method for a protective fence for non-destructively diagnosing the soundness of the protective fence based on the vibration characteristics obtained from the vibration waveform generated by the excitation of the struts of the protective fence,
Based on the natural vibration data from the vibration characteristics, corrosion in the support, lack of embedment length, bending, deterioration in rigidity or reduction in fixing force due to reduction in binding force of the base are evaluated,
Based on the shock elastic wave data from among the vibration characteristics, the time interval between the time when the excitation started and the time when the reflected wave, which is the shock elastic wave, was observed, and the time interval measured at the normal column Evaluate the penetration length, bend position and/or corrosion position in the strut by comparing
A non-destructive diagnosis method for a protective fence for diagnosing the soundness of the protective fence by evaluation based on the natural vibration and evaluation based on the impact elastic wave,
The evaluation based on the shock elastic wave data is
identifying a reflected wave from the vibration waveform;
a step of acquiring a time interval between a start time of excitation of the struts of the protective fence and a time of observation of reflected waves;
comparing the obtained time interval with the time interval in a healthy guard fence;
and determining the soundness of the protective fence based on the result of the comparison,
The step of acquiring the time interval between the start time of excitation of the pillar of the protective fence and the observation time of the reflected wave is the first step of the autocorrelation function obtained from the vibration waveform generated by the excitation of the pillar of the protective fence. A non-destructive diagnosis method for a protective fence, characterized by the step of acquiring the time interval from one peak. A non-destructive diagnosis method for a protective fence for non-destructively diagnosing the soundness of the protective fence based on the vibration characteristics obtained from the vibration waveform generated by the excitation of the struts of the protective fence,
Based on the natural vibration data from the vibration characteristics, corrosion in the support, lack of embedment length, bending, deterioration in rigidity or reduction in fixing force due to reduction in binding force of the base are evaluated,
Based on the shock elastic wave data from among the vibration characteristics, the time interval between the time when the excitation started and the time when the reflected wave, which is the shock elastic wave, was observed, and the time interval measured at the normal column Evaluate the penetration length, bend position and/or corrosion position in the strut by comparing
A non-destructive diagnosis method for a protective fence for diagnosing the soundness of the protective fence by evaluation based on the natural vibration and evaluation based on the impact elastic wave,
The evaluation based on the shock elastic wave data is
a step of identifying a reflected wave from the vibration waveform generated by the vibration applied to the strut part of the protective fence to be diagnosed;
acquiring a time interval between the excitation start time and the reflected wave observation time for the specified reflected wave;
identifying the position of the reflecting surface where the reflected wave was generated from the obtained time interval;
determining the soundness of the protective fence based on the identified position of the reflective surface;
The step of acquiring the time interval between the start time of excitation of the pillar of the protective fence and the observation time of the reflected wave is the first step of the autocorrelation function obtained from the vibration waveform generated by the excitation of the pillar of the protective fence. A non-destructive diagnosis method for a protective fence, characterized by the step of acquiring the time interval from one peak. Using one vibration waveform generated by excitation of the strut part of the protective fence,
6. The non-destructive diagnosis of the protective fence according to any one of claims 1 to 5, wherein the evaluation based on the data of the natural vibration and the evaluation based on the data of the impact elastic wave are performed. Method. Using the vibration waveform generated by the excitation of the struts of the protective fence, evaluation based on the data of the natural vibration is performed as a primary screening,
After that, for the protective fence that was determined to have a decrease in rigidity or a decrease in fixing force at the support in the primary screening,
Evaluation based on the data of the shock elastic wave is performed as a secondary screening by using the vibration waveform generated by the excitation of other parts of the support fence of the protective fence. 6. The non-destructive diagnosis method for protective fences according to any one of 5. Evaluation based on the data of the natural vibration,
a step of frequency analysis of the vibration waveform to obtain a frequency distribution;
a step of selecting a peak frequency in a specific vibration mode from the obtained natural vibration peaks of the frequency distribution as an evaluation peak frequency;
comparing the selected rated peak frequency with a similarly obtained rated peak frequency for a guard fence in good condition;
2. A non-destructive diagnosis method for a protective fence according to claim 1, further comprising the step of judging the soundness of said protective fence based on the result of the comparison. When acquiring the data of the natural vibration, a sensor is arranged on the side surface of the column near the ground, and the vibration waveform is obtained by striking from the vicinity of the sensor to vibrate, and the data of the natural vibration is obtained. 9. A non-destructive diagnosis method for a protective fence according to any one of claims 1 to 8, characterized in that the information is acquired. The evaluation based on the shock elastic wave data is
identifying a reflected wave from the vibration waveform;
a step of acquiring a time interval between a start time of excitation of the struts of the protective fence and a time of observation of reflected waves;
comparing the obtained time interval with the time interval in a healthy guard fence;
10. The non-destructive diagnosis method for a protective fence according to any one of claims 1 to 9, further comprising a step of judging the soundness of the protective fence based on the result of the comparison. The evaluation based on the shock elastic wave data is
a step of identifying a reflected wave from the vibration waveform generated by the vibration applied to the strut part of the protective fence to be diagnosed;
acquiring a time interval between the excitation start time and the reflected wave observation time for the specified reflected wave;
identifying the position of the reflecting surface where the reflected wave was generated from the obtained time interval;
and determining the soundness of the protective fence based on the specified position of the reflecting surface. Destructive diagnostic method. The step of acquiring the time interval between the excitation start time of the pillar of the protective fence and the reflected wave observation time is the step of acquiring the time interval from the vibration waveform generated by the excitation of the pillar of the protective fence. 12. The non-destructive diagnosis method for protective fences according to claim 10 or 11, characterized in that: When acquiring the data of the impact elastic wave, a sensor is placed near the top of the column, and the vibration waveform is obtained by striking and vibrating from the vicinity of the sensor, and the data of the impact elastic wave is acquired. 13. The non-destructive diagnosis method for protective fences according to any one of claims 1 to 12, characterized in that: A nondestructive diagnostic system for protective fences used in the nondestructive diagnostic method for protective fences according to any one of claims 1 to 13,
a vibrating means for vibrating the pillars of the protective fence;
vibration characteristic acquisition means for acquiring vibration characteristics from the vibration waveform generated by the excitation;
A first evaluation of deterioration in rigidity or reduction in fixing force due to corrosion, insufficient embedment length, bending, and reduction in binding force of the base portion in the support portion based on the natural vibration data from among the vibration characteristics. a means of evaluation;
second evaluation means for evaluating the penetration length, bending position, and corrosion position in the support column based on the data of the impact elastic wave selected from the vibration characteristics;
A non-destructive diagnosis system for a protective fence, comprising diagnostic means for diagnosing soundness of the protective fence based on evaluation based on the first evaluation means and the second evaluation means. The first evaluation means is
a step of frequency analysis of the vibration waveform to obtain a frequency distribution;
a step of selecting the minimum peak frequency as an evaluation peak frequency from among the peak frequencies having an intensity exceeding a predetermined threshold value from the frequencies of the natural vibration peaks of the obtained frequency distribution;
comparing the selected rated peak frequency with the rated peak frequency in a guard fence in good condition;
15. The non-destructive diagnosis system for protective fences according to claim 14, wherein the step of judging the soundness of said protective fences is sequentially executed based on the result of the comparison. The first evaluation means is
The frequency distribution was obtained by analyzing the frequency of the vibration waveform generated by the excitation of the pillars of the protective fence, which was previously known to have no corrosion, insufficient penetration length, bending, or lowering of the binding force of the foundation. setting, as a reference value for determination, the minimum peak frequency among the peak frequencies having an intensity exceeding a predetermined threshold value from the frequencies of the natural vibration peaks of the obtained frequency distribution;
obtaining a frequency distribution by frequency-analyzing the vibration waveform generated by the excitation of the struts of the protective fence to be diagnosed;
a step of selecting the minimum peak frequency as an evaluation peak frequency from among the peak frequencies having an intensity exceeding a predetermined threshold value from the frequencies of the natural vibration peaks of the obtained frequency distribution;
comparing the selected evaluation peak frequency with the reference value;
15. The non-destructive diagnosis system for protective fences according to claim 14, wherein the step of judging the soundness of said protective fences is sequentially executed based on the result of the comparison. The first evaluation means is
a step of frequency analysis of the vibration waveform to obtain a frequency distribution;
a step of selecting a peak frequency in a specific vibration mode from the obtained natural vibration peaks of the frequency distribution as an evaluation peak frequency;
comparing the selected rated peak frequency with a similarly obtained rated peak frequency for a guard fence in good condition;
15. The non-destructive diagnosis system for protective fences according to claim 14, wherein the step of judging the soundness of said protective fences is sequentially executed based on the result of the comparison. The first evaluation means is
obtaining a vibration waveform by causing the strut to vibrate in a longitudinal vibration mode with the vibrating means;
a step of frequency-analyzing the obtained vibration waveform to obtain a frequency distribution;
obtaining the natural frequency of the longitudinal vibration mode from the obtained frequency distribution;
obtaining the total length of the strut based on the obtained natural frequency of the longitudinal vibration mode;
15. The protective fence according to claim 14, further comprising a step of calculating the embedded length of the support by subtracting the length of the portion exposed above the ground from the obtained total length of the support. Nondestructive diagnostic system. The second evaluation means is
identifying a reflected wave from the vibration waveform;
a step of acquiring a time interval between a start time of excitation of the struts of the protective fence and a time of observation of reflected waves;
comparing the obtained time interval with the time interval in a healthy guard fence;
19. The method according to any one of claims 14 to 18, characterized in that the step of judging the soundness of the protective fence based on the result of the comparison is sequentially executed. Non-destructive diagnostic system for guardrails. The second determination means is
a step of identifying a reflected wave from the vibration waveform generated by the vibration applied to the strut part of the protective fence to be diagnosed;
acquiring a time interval between the excitation start time and the reflected wave observation time for the specified reflected wave;
identifying the position of the reflecting surface where the reflected wave was generated from the obtained time interval;
and determining the soundness of the protective fence based on the specified position of the reflecting surface. Non-destructive diagnostic system for guardrails as described in paragraph. A non-destructive diagnostic device for use in implementing the non-destructive diagnostic system for protective fences according to any one of claims 14 to 20,
a hammer that strikes the posts of the protective fence to generate vibration due to excitation;
a sensor that detects the generated vibration as a signal;
a preamplifier that amplifies the detected signal;
a digital oscilloscope that converts the amplified signal to digital and displays it as a vibration waveform;
a personal computer that diagnoses the soundness of the protective fence based on the vibration waveform,
A non-destructive diagnostic device, wherein the personal computer stores a program for converting the vibration waveform into data of natural vibration and impact elastic wave, and diagnosing soundness of the protective fence. 22. A non-destructive diagnostic apparatus according to claim 21, wherein said sensor is an AE sensor.

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