JP2003269944A - Measurement method and device for crack depth developed in structure - Google Patents
Measurement method and device for crack depth developed in structureInfo
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- JP2003269944A JP2003269944A JP2002070309A JP2002070309A JP2003269944A JP 2003269944 A JP2003269944 A JP 2003269944A JP 2002070309 A JP2002070309 A JP 2002070309A JP 2002070309 A JP2002070309 A JP 2002070309A JP 2003269944 A JP2003269944 A JP 2003269944A
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- crack
- resonance
- crack depth
- sound wave
- frequency
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- Investigating Or Analyzing Materials By The Use Of Ultrasonic Waves (AREA)
Abstract
Description
【発明の詳細な説明】Detailed Description of the Invention
【0001】[0001]
【発明の属する技術分野】本発明は,建物や多くの構造
物,材料に生じるひび割れの深さを音響によって非破壊
計測する構造物に生じたひび割れ深さの計測方法及び装
置に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for measuring a crack depth generated in a structure for acoustically nondestructively measuring the depth of a crack generated in a building, many structures and materials.
【0002】[0002]
【従来の技術】従来,構造物に生じるひび割れの深さを
測定するためには,超音波・弾性波加振による方法がと
られていた。即ち,いくつかの発振子,受振子をコンク
リートに取り付け,超音波もしくは弾性波(主に表面
波)の到達時間などからクラック深さを推定していた。2. Description of the Related Art Conventionally, ultrasonic and elastic wave excitation methods have been used to measure the depth of cracks in a structure. That is, some oscillators and geophones were attached to concrete, and the crack depth was estimated from the arrival time of ultrasonic waves or elastic waves (mainly surface waves).
【0003】しかし,超音波を使用したひび割れ深さの
測定方法では,コンクリート内部での超音波の減衰が大
きいため,厚いコンクリート等に生じたひび割れ深さの
測定は困難であるという問題点がある。However, in the method of measuring the crack depth using ultrasonic waves, there is a problem in that it is difficult to measure the crack depth generated in thick concrete or the like because the ultrasonic waves are largely attenuated inside the concrete. .
【0004】また,弾性波を使用したひび割れ深さの測
定方法では,分析周波数を低くすれば超音波による方法
と比較して厚いコンクリート(深いクラック)であって
も測定が可能であるが,波長が長くなるので,解析精度
が低下するという問題点がある。In addition, in the method of measuring the crack depth using elastic waves, even if thick concrete (deep crack) can be measured as compared with the method using ultrasonic waves, if the analysis frequency is lowered, the wavelength can be measured. However, there is a problem in that the accuracy of analysis is reduced because of the long length.
【0005】また,分析周波数を高くしてひび割れ深さ
を測定すれば,解析精度は向上するが,超音波の場合と
同様に減衰が大きくなり,厚いコンクリートでは測定が
困難となるという問題点がある。Further, if the cracking depth is measured by increasing the analysis frequency, the analysis accuracy is improved, but the attenuation becomes large as in the case of ultrasonic waves, and there is a problem that measurement becomes difficult with thick concrete. is there.
【0006】[0006]
【発明が解決しようとする課題】本発明は,上記従来技
術の問題点を解決し,構造物に生じた深いひび割れの深
さを計測でき,かつ,解析精度の高いひび割れ深さの計
測手段を提供することを課題とする。SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the prior art and provides a crack depth measuring means capable of measuring the depth of deep cracks formed in a structure and having high analysis accuracy. The challenge is to provide.
【0007】[0007]
【課題を解決するための手段】本発明においては,材料
の音響,振動の伝搬特性からひび割れ深さを求めるので
はなく,ひび割れ内部に生じる共鳴現象を利用する。In the present invention, the crack depth is not obtained from the acoustic and vibration propagation characteristics of the material, but the resonance phenomenon occurring inside the crack is utilized.
【0008】まず,本発明の原理となる共鳴理論につい
て簡単に説明する。ひび割れが生じたある厚さの構造体
のひび割れ内部に向けて音波を送ると,ひび割れ内部に
は,入射波と反射波が重ね合わさり,干渉した波が形成
される。また,特定のひび割れ深さの場合に,ひび割れ
内部の干渉波の強さが最大になり,強い音が発生する。
これを音波の共鳴と呼ぶ。そして,共鳴しているひび割
れ内部の波(定常波)の周波数(共鳴周波数)は,ひび
割れの深さにより定まる。これを音響共鳴理論という。First, the resonance theory, which is the principle of the present invention, will be briefly described. When a sound wave is sent to the inside of a crack of a cracked structure of a certain thickness, an incident wave and a reflected wave are superposed inside the crack, and an interfering wave is formed. Further, at a specific crack depth, the intensity of the interference wave inside the crack is maximized and a strong sound is generated.
This is called sound wave resonance. The frequency (resonance frequency) of the resonating wave inside the crack (stationary wave) is determined by the depth of the crack. This is called acoustic resonance theory.
【0009】ここで,ひび割れの先端が構造体の裏側に
到達せず閉じていれば,図13に示すように,閉管とし
ての特徴が現れる。即ち,波長をλ,共鳴周波数をf,
ひび割れ深さをL,音速をc,自然数nとすれば,図1
3において,(n−1) λ/2+λ/4=L式が成り立
つ。c=λfであるから,上記の式から,共鳴周波数f
={(n−1)/2+1/4}c/Lとなる。Here, if the tip of the crack does not reach the back side of the structure and is closed, a characteristic as a closed tube appears as shown in FIG. That is, the wavelength is λ, the resonance frequency is f,
Assuming that the crack depth is L, the speed of sound is c, and the natural number is n,
3, the equation (n-1) λ / 2 + λ / 4 = L holds. Since c = λf, from the above equation, the resonance frequency f
= {(N-1) / 2 + 1/4} c / L.
【0010】また,ひび割れの先端が構造体の裏側に到
達していれば,図14に示すように,開管としての特徴
が現れる。即ち,波長をλ,共鳴周波数をf,ひび割れ
深さをL,音速をc,自然数nとすれば,図14におい
て,nλ/2=L式が成り立ち,共鳴周波数f=nc/
2Lとなる。If the tip of the crack reaches the back side of the structure, a characteristic as an open tube appears as shown in FIG. That is, assuming that the wavelength is λ, the resonance frequency is f, the crack depth is L, the sound velocity is c, and the natural number is n, in FIG. 14, nλ / 2 = L formula is established, and the resonance frequency f = nc /
It becomes 2L.
【0011】図15には,長さ100mmの閉管,開管に
対し,平面波入射条件のインピーダンスモデルにより,
開口周辺の音圧とアドミッタンスを計算した例が示され
る。図15によると,各条件毎に共鳴現象によるピーク
やディップが異なる周波数に現れるのがわかる。このよ
うに,共鳴する音の共鳴周波数はひび割れ深さで定ま
る。従って,共鳴周波数から逆算して,当該構造物のひ
び割れ深さが算出できる。そこで,本発明の構造物に生
じたひび割れ深さの計測方法は,対象試験体に試験音波
を放射するステップと,対象試験体のひび割れの表面入
口の空気粒子の振動速度を測定するステップと,測定し
た振動速度に基づいて,対象試験体のひび割れ内部に生
じた共鳴音波の共鳴周波数を分析するステップとを有
し,分析した共鳴周波数からひび割れ深さを求めるよう
に構成される。FIG. 15 shows an impedance model under the plane wave incidence condition for a closed tube and an open tube having a length of 100 mm.
An example of calculating sound pressure and admittance around the opening is shown. It can be seen from FIG. 15 that peaks and dips due to the resonance phenomenon appear at different frequencies for each condition. In this way, the resonance frequency of the resonating sound is determined by the crack depth. Therefore, the crack depth of the structure can be calculated by calculating backward from the resonance frequency. Therefore, the method for measuring the crack depth generated in the structure of the present invention comprises the steps of radiating a test sound wave to the target test body, and measuring the vibration velocity of air particles at the surface entrance of the crack of the target test body. And analyzing the resonance frequency of the resonance sound wave generated inside the crack of the target test body based on the measured vibration speed, and determining the crack depth from the analyzed resonance frequency.
【0012】また,本発明の構造物に生じたひび割れ深
さの計測方法は,対象試験体に試験音波を放射するステ
ップと,対象試験体のひび割れ内部に生じた共鳴音波を
受音するステップと,受音した共鳴音波の共鳴周波数を
分析するステップとを有し,分析した共鳴周波数からひ
び割れ深さを求めるように構成される。Further, the method of measuring the crack depth generated in the structure of the present invention comprises the steps of radiating a test sound wave to the target test body and receiving a resonance sound wave generated inside the crack of the target test body. And a step of analyzing the resonance frequency of the received resonance sound wave, and is configured to obtain the crack depth from the analyzed resonance frequency.
【0013】また,本発明の構造物に生じたひび割れ深
さの計測方法は,対象試験体に圧縮空気を吹き付けるス
テップと,対象試験体のひび割れ内部に生じた共鳴音波
を受音するステップと,受音した共鳴音波の共鳴周波数
を分析するステップとを有し,分析した共鳴周波数から
ひび割れ深さを求めるように構成される。Further, the method of measuring the crack depth generated in the structure of the present invention comprises the steps of blowing compressed air to the target test body, and receiving the resonance sound waves generated inside the crack of the target test body. And a step of analyzing the resonance frequency of the received resonance sound wave, and the crack depth is obtained from the analyzed resonance frequency.
【0014】また,本発明の構造物に生じたひび割れ深
さの計測装置は,対象試験体に試験音波を放射する手段
と,対象試験体のひび割れの表面入口の空気粒子の振動
速度を測定する手段と,測定した振動速度に基づいて,
対象試験体のひび割れ内部に生じた共鳴音波の共鳴周波
数を分析する手段と,分析した共鳴周波数からひび割れ
深さを求める手段とを備えるように構成される。Further, the apparatus for measuring the crack depth generated in the structure of the present invention measures the means for radiating the test sound wave to the target test body and the vibration velocity of the air particles at the surface entrance of the crack of the target test body. Based on the means and the measured vibration velocity,
It is configured to include a means for analyzing the resonance frequency of the resonance sound wave generated inside the crack of the target test body and a means for obtaining the crack depth from the analyzed resonance frequency.
【0015】また,本発明の構造物に生じたひび割れ深
さの計測装置は,対象試験体に試験音波を放射する手段
と,対象試験体のひび割れ内部に生じた共鳴音波を受音
する手段と,受音した共鳴音波の共鳴周波数を分析する
手段と,分析した共鳴周波数からひび割れ深さを求める
手段とを備えるように構成される。Further, the measuring device for the crack depth generated in the structure of the present invention comprises means for radiating a test sound wave to the target test body and means for receiving the resonance sound wave generated inside the crack of the target test body. And a means for analyzing the resonance frequency of the received resonance sound wave and a means for obtaining the crack depth from the analyzed resonance frequency.
【0016】このような構成をとる場合に,前記対象試
験体のひび割れ内部に生じた共鳴音波を受音する手段
に,前記試験放射音を極力排除し,対象試験体のひび割
れ内部を経由した共鳴音波に強く感応するための遮断装
置(カバー等)を設けてもよい。In the case of adopting such a constitution, the means for receiving the resonance sound wave generated inside the crack of the target test body eliminates the test radiated sound as much as possible, and resonates through the inside of the crack of the target test body. A blocking device (cover or the like) for strongly responding to sound waves may be provided.
【0017】また,本発明の構造物に生じたひび割れ深
さの計測装置は,対象試験体に圧縮空気を吹きつける手
段と,対象試験体のひび割れ内部に生じた共鳴音波を受
音する手段と,受音した共鳴音波の共鳴周波数を分析す
る手段と,分析した共鳴周波数からひび割れ深さを求め
る手段とを備えるように構成される。The crack depth measuring device of the structure of the present invention comprises means for blowing compressed air to the target test body and means for receiving the resonance sound waves generated inside the crack of the target test body. And a means for analyzing the resonance frequency of the received resonance sound wave and a means for obtaining the crack depth from the analyzed resonance frequency.
【0018】本発明は,上記の構成をとることにより,
構造物に生じたひび割れ内部に生じた共鳴音波の共鳴周
波数を捉えることが可能となり,共鳴周波数を分析する
ことを通じてひび割れ深さを計測することができる。According to the present invention, by adopting the above configuration,
It is possible to capture the resonance frequency of the resonance sound wave generated inside the crack generated in the structure, and the crack depth can be measured by analyzing the resonance frequency.
【0019】また,基本共鳴周波数に加えて,より高次
の共鳴周波数も検知して計測の精度を向上させることが
できる。In addition to the fundamental resonance frequency, higher order resonance frequencies can be detected to improve the accuracy of measurement.
【0020】[0020]
【発明の実施の形態】図1は,本発明の第1の実施の形
態におけるひび割れ深さの計測方法の概要を示す図であ
る。本発明の第1の実施の形態におけるひび割れ深さの
計測方法においては,共鳴現象が生じるとひび割れの表
面入口の空気粒子の動きが活発になることに着目し,試
験音による空気粒子の動きを検知する粒子速度センサー
を用いる。DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagram showing an outline of a crack depth measuring method according to a first embodiment of the present invention. In the crack depth measuring method according to the first embodiment of the present invention, attention is paid to the fact that the movement of the air particles at the surface entrance of the crack becomes active when the resonance phenomenon occurs. Uses a particle velocity sensor to detect.
【0021】1は,構造体に生じたひび割れ内部に向け
て試験音波を放射するスピーカであり,2は,ひび割れ
が生じた対象試験体である。3は,ひび割れの表面入口
の振動する空気粒子の速度を検知し,電気信号に変換す
る粒子速度センサーである。4は,粒子速度センサーか
ら送信された電気信号に基づいて周波数分析を行い,共
鳴周波数成分の大きさを測定する周波数分析装置であ
り,5は,音波を捉え,音響エネルギーを電気エネルギ
ーに変換するマイクロフォンである。Reference numeral 1 is a speaker which emits a test sound wave toward the inside of a crack formed in the structure, and 2 is a target test body in which the crack is generated. A particle velocity sensor 3 detects the velocity of vibrating air particles at the surface entrance of the crack and converts it into an electric signal. Reference numeral 4 is a frequency analysis device for performing frequency analysis based on the electric signal transmitted from the particle velocity sensor to measure the magnitude of the resonance frequency component, and 5 is for capturing a sound wave and converting acoustic energy into electric energy. It is a microphone.
【0022】まず,スピーカ1から対象試験体2に向け
て,周波数によるひび割れ深さの計測に十分な大きさの
帯域幅を持った周波数特性の試験音波を放射する。スピ
ーカ1から放射された試験音波によって,対象試験体2
のひび割れ内部において,入射波と反射波とが干渉し
て,共鳴現象が生じる。そして,表面に近接させた空気
粒子の動きを検知する粒子速度センサー3が,共鳴現象
によって振動する空気粒子速度を測定し,電気信号に変
換する。First, a test sound wave having a frequency characteristic having a bandwidth large enough to measure the crack depth by frequency is radiated from the speaker 1 toward the target test body 2. By the test sound wave radiated from the speaker 1, the target test body 2
Inside the crack, the incident wave and the reflected wave interfere with each other to cause a resonance phenomenon. Then, the particle velocity sensor 3 that detects the movement of the air particles brought close to the surface measures the velocity of the air particles that vibrate due to the resonance phenomenon and converts them into an electric signal.
【0023】次に,粒子速度センサー3から送信された
電気信号に基づいて周波数分析装置4が各周波数成分の
大きさを測定する。そして,振幅がピークを示す周波数
が共鳴周波数として検出され,共鳴理論に基づいて,ひ
び割れ深さが求められる。Next, the frequency analyzer 4 measures the magnitude of each frequency component based on the electric signal transmitted from the particle velocity sensor 3. Then, the frequency at which the amplitude shows a peak is detected as the resonance frequency, and the crack depth is obtained based on the resonance theory.
【0024】なお,粒子速度センサー3とマイクロフォ
ン5を併置したのは,スピーカ1の放射音の周波数特性
が平坦でなく,粒子速度センサー3だけ使用すると,ス
ピーカ1の周波数特性を測ってしまう危険があるため,
併置したマイクロフォン5の出力で粒子速度センサー3
の出力を相対化することにより,スピーカ1の周波数特
性が平坦でないことの問題点を解決するためである。こ
の相対化した値を,音響アドミッタンスという。The particle velocity sensor 3 and the microphone 5 are arranged side by side because the frequency characteristic of the radiated sound of the speaker 1 is not flat, and if only the particle velocity sensor 3 is used, there is a risk of measuring the frequency characteristic of the speaker 1. Because,
Particle velocity sensor 3 with the output of microphone 5
This is to solve the problem that the frequency characteristic of the speaker 1 is not flat by making the output of the above relative. This relativized value is called acoustic admittance.
【0025】図2は,第1の実施の形態において使用す
る周波数分析装置4の構成図である。粒子速度センサー
3によって,ひび割れ表面入口の空気粒子速度が電気信
号に変換されると,その電気信号は,周波数分析装置4
のA/D変換器41に送信され,ディジタル信号に変換
される。FIG. 2 is a block diagram of the frequency analyzer 4 used in the first embodiment. When the particle velocity sensor 3 converts the air particle velocity at the inlet of the crack surface into an electric signal, the electric signal is converted into a frequency analysis device
Is transmitted to the A / D converter 41 and is converted into a digital signal.
【0026】一方,マイクロフォン5の出力が,周波数
分析装置4のA/D変換器42に送信され,ディジタル
信号に変換される。そして,上記ディジタル信号が,そ
れぞれフーリエ変換部43及びフーリエ変換部44によ
りフーリエ変換された後,音響アドミッタンス計算部4
5により音響アドミッタンスが計算され,周波数情報出
力部46によって各周波数成分の大きさが出力される。
出力された周波数情報から共鳴周波数を抽出し,ひび割
れ深さを推定する方法としては,周波数情報を数値解析
して周波数のピーク値を算出し,それから共鳴周波数に
対応するひび割れ深さを決定してもよいし,周波数情報
をグラフ化してディスプレイまたはプリンタに出力し,
そのグラフから計測者が読み取るようにしてもよい。On the other hand, the output of the microphone 5 is transmitted to the A / D converter 42 of the frequency analyzer 4 and converted into a digital signal. The digital signals are Fourier transformed by the Fourier transform unit 43 and the Fourier transform unit 44, respectively, and then the acoustic admittance calculation unit 4
5, the acoustic admittance is calculated, and the frequency information output unit 46 outputs the magnitude of each frequency component.
The method of extracting the resonance frequency from the output frequency information and estimating the crack depth is to numerically analyze the frequency information, calculate the peak value of the frequency, and then determine the crack depth corresponding to the resonance frequency. Or you can output the frequency information as a graph on a display or printer,
The measurer may read the graph.
【0027】図3乃至図7は,第1の実施の形態におけ
る詳細な実験例を示す図である。図3は,ひび割れ深さ
を変化させた例,図4は,閉管,開管の場合の比較例,
図5は,溝内部が平滑でない例,図6は,溝幅を変化さ
せた例,図7は,異なる構造体で開管の場合の例を示す
グラフである。3 to 7 are diagrams showing detailed experimental examples in the first embodiment. Fig. 3 shows an example in which the crack depth is changed, Fig. 4 shows a comparative example with closed and open pipes,
FIG. 5 is a graph showing an example in which the inside of the groove is not smooth, FIG. 6 is an example in which the groove width is changed, and FIG.
【0028】図3は,アルミ材料で溝深さを変えられる
試験体を製作し,その溝直上に熱線タイプの粒子速度セ
ンサーとマイクロフォンを併置した音響アドミッタンス
を使用して観測したグラフである。このようにして観測
した結果,図3に示したグラフにおいて,溝深さ80m
m,40mm,20mmごとに,それぞれスペクトルピーク
が観測された。そして,当該グラフにおいて,各スペク
トルのピークから下に垂直線を引き,横軸との交点を読
み取ると共鳴周波数が検出できる。FIG. 3 is a graph obtained by making a test body in which the groove depth can be changed with an aluminum material and using an acoustic admittance in which a heat ray type particle velocity sensor and a microphone are arranged directly above the groove. As a result of observing in this way, in the graph shown in FIG. 3, the groove depth is 80 m.
Spectral peaks were observed for m, 40 mm, and 20 mm. Then, in the graph, a vertical line is drawn downward from the peak of each spectrum and the intersection with the horizontal axis is read to detect the resonance frequency.
【0029】本実施例では,閉管でn=1の基本振動の
場合を基本としており,音響共鳴理論による閉管の場合
の共鳴周波数を求める式f={(n−1)/2+1/
4}c/Lが当てはまり,共鳴理論の適用が可能であ
る。The present embodiment is based on the case of a closed tube having a fundamental vibration of n = 1, and an expression f = {(n-1) / 2 + 1 / for obtaining a resonance frequency in the case of a closed tube based on the acoustic resonance theory.
4} c / L is applicable, and the resonance theory can be applied.
【0030】次に,アルミ材料の深さ100mmの溝の他
端が開閉の2条件で実験した例を図4のグラフに示す。
この例では,1次モードが,閉管の場合700Hzに現
れ,開管の場合,閉管の場合の約2倍の1.5kHz付
近に現れており,共鳴理論の適用が妥当と判断される。Next, an example of an experiment conducted under the two conditions of opening and closing the other end of the aluminum material groove having a depth of 100 mm is shown in the graph of FIG.
In this example, the first-order mode appears at 700 Hz in the case of the closed tube, and appears in the vicinity of 1.5 kHz which is about twice the case of the closed tube in the case of the open tube, and it is judged that the application of the resonance theory is appropriate.
【0031】次に,構造体の溝内部が平滑でないコンク
リートひび割れ試験体を対象に,溝深さ10mm,20m
m,30mm,40mmの試験体での観測例を,図5のグラ
フに示す。この例でも,異なる周波数においてスペクト
ルピークが観測され,共鳴理論の適用が妥当であること
がわかる。Next, for a concrete crack test body in which the inside of the groove of the structure is not smooth, the groove depth is 10 mm and 20 m.
An example of observations with m, 30 mm, and 40 mm test specimens is shown in the graph of FIG. In this example as well, spectral peaks are observed at different frequencies, demonstrating that the application of resonance theory is appropriate.
【0032】次に,図6に,アルミ材料で溝の幅を0.
6〜1mmまで変えた時の観測例を示す。この観測例で
は,溝幅が減ずるとピークが鈍化して観測される傾向に
あり,微細ひび割れの推定には,感度向上等が必要であ
ると考えられるものの,共鳴理論が妥当すると判断され
る。Next, referring to FIG. 6, the groove width of the aluminum material is set to 0.
An example of observation when changing from 6 to 1 mm is shown. In this observation example, the peak tends to be observed as the groove width decreases, and it is considered that the sensitivity of the fine crack must be improved, but the resonance theory is considered to be valid.
【0033】次に,40mm厚のコンクリート製敷石板を
割り,破断面を密着させ,下面を油土で閉じた非直線的
断面長の空隙部の観測例を図7のグラフに示す。この観
測例では,音響共鳴理論における開管としての特徴が現
れ,1.5kHz付近にピークが観測されていることか
ら,共鳴理論が妥当する。Next, a graph of FIG. 7 shows an observation example of a non-linear cross-section length void in which a 40-mm-thick concrete paving stone plate is cut, the fracture surfaces are brought into close contact, and the lower surface is closed with oil soil. In this observation example, the characteristic as an open tube in the acoustic resonance theory appears and a peak is observed near 1.5 kHz, so the resonance theory is valid.
【0034】ここで,上記第1の実施の形態では,広い
帯域幅を持つ試験音波をスピーカから放射しているが,
スピーカから放射される試験音波をスイープし,時間と
ともに周波数を徐々に増加させることによっても共鳴周
波数を計測することもできる。試験音波をスイープする
場合の周波数分析装置6の構成例を図8に示す。Here, in the first embodiment, the test sound wave having a wide bandwidth is radiated from the speaker.
The resonance frequency can also be measured by sweeping the test sound wave emitted from the speaker and gradually increasing the frequency with time. FIG. 8 shows a configuration example of the frequency analysis device 6 when sweeping the test sound wave.
【0035】周波数分析装置6の周波数制御部60は,
時間とともにスイープする周波数情報をスピーカ出力周
波数制御部61に送信し,スピーカ出力周波数制御部6
1はこの周波数情報をD/A変換器62に送信する。そ
して,D/A変換器62によりディジタル信号がアナロ
グ信号に変換され,スピーカ1から音波として放射され
る。次に,粒子速度センサー3からの出力が,周波数分
析装置6のA/D変換器63に送信される。A/D変換
器63により変換されたディジタル信号が周波数情報出
力部64に送信され,周波数情報出力部64において各
周波数情報が検出される。The frequency control unit 60 of the frequency analyzer 6 is
The frequency information that sweeps with time is transmitted to the speaker output frequency control unit 61, and the speaker output frequency control unit 6
1 transmits this frequency information to the D / A converter 62. Then, the D / A converter 62 converts the digital signal into an analog signal, which is radiated as a sound wave from the speaker 1. Next, the output from the particle velocity sensor 3 is transmitted to the A / D converter 63 of the frequency analyzer 6. The digital signal converted by the A / D converter 63 is transmitted to the frequency information output unit 64, and the frequency information output unit 64 detects each frequency information.
【0036】図9は,本発明の第2の実施の形態におけ
るひび割れ深さの計測方法の概要を示す図である。第2
の実施の形態においては,ひび割れ内部に入るような微
細マイクロフォン5を使用する。FIG. 9 is a diagram showing an outline of a crack depth measuring method according to the second embodiment of the present invention. Second
In the above embodiment, the fine microphone 5 that enters the inside of the crack is used.
【0037】まず,スピーカ1から対象試験体に向け
て,周波数によるひび割れ深さの計測に十分な大きさの
帯域幅を持った周波数特性の試験音波を放射する。スピ
ーカ1から放射された試験音波によって,対象試験体2
のひび割れ内部において,入射波と反射波が干渉して,
共鳴現象が生じる。次に,対象試験体2のひび割れ内部
または入口部分に設置した微細マイクロフォン5が,ひ
び割れ内部の共鳴音波を受音し,その音響エネルギーを
電気エネルギーに変換する。First, a test sound wave having a frequency characteristic having a bandwidth large enough to measure the crack depth by frequency is radiated from the speaker 1 toward the target test body. By the test sound wave radiated from the speaker 1, the target test body 2
Inside the crack, the incident wave and the reflected wave interfere,
Resonance phenomenon occurs. Next, the fine microphone 5 installed inside the crack or the entrance portion of the target test body 2 receives the resonance sound wave inside the crack and converts the acoustic energy into electric energy.
【0038】そして,マイクロフォン5から送信された
電気信号に基づいて,周波数分析装置4が各周波数成分
の大きさを測定する。そして,振幅がピークを示す周波
数を共鳴周波数として検出し,共鳴理論に基づいて,ひ
び割れ深さを算出する。Then, the frequency analyzer 4 measures the magnitude of each frequency component based on the electric signal transmitted from the microphone 5. Then, the frequency at which the amplitude shows a peak is detected as the resonance frequency, and the crack depth is calculated based on the resonance theory.
【0039】第2の実施の形態でも,共鳴周波数を分析
することによって第1の実施の形態と同様にひび割れ深
さを算出することができる。なお,放射試験音波をスイ
ープさせて観測する方法によっても同様にひび割れ深さ
を求めることができる。Also in the second embodiment, the crack depth can be calculated by analyzing the resonance frequency as in the first embodiment. Note that the crack depth can also be obtained in the same way by observing the sound waves emitted by the radiation test.
【0040】図10は,本発明の第3の実施の形態にお
けるひび割れ深さの計測方法の概要を示す図である。第
3の実施の形態においては,マイクロフォン5にカバー
7を付けて試験放射音を極力排除して,ひび割れ内部を
経由した音波に強く感応するような工夫をした受音装置
を使用する。このような工夫をすることにより,共鳴音
波に対する感度を向上させて,ひび割れ深さ測定の精度
を高めることができる。FIG. 10 is a diagram showing an outline of a crack depth measuring method according to the third embodiment of the present invention. In the third embodiment, a cover 7 is attached to the microphone 5 to eliminate the test radiated sound as much as possible, and a sound receiving device is used that is sensitive to the sound wave passing through the inside of the crack. By making such a device, the sensitivity to resonance sound waves can be improved and the accuracy of crack depth measurement can be improved.
【0041】まず,スピーカ1から対象試験体に向け
て,周波数によるひび割れ深さの計測に十分な大きさの
帯域幅を持った周波数特性の試験音波を放射する。スピ
ーカ1から放射された試験音波によって,対象試験体2
のひび割れ内部において,入射波と反射波が干渉して,
共鳴現象が生じる。次に,マイクロフォン5が,ひび割
れ内部の共鳴音波を受音し,その音響エネルギーを電気
エネルギーに変換する。そして,マイクロフォン5から
送信された電気信号に基づいて,周波数分析装置4が各
周波数成分の大きさを測定する。そして,振幅がピーク
を示す周波数を共鳴周波数として検出し,共鳴理論に基
づいて,ひび割れ深さを算出する。First, a test sound wave having a frequency characteristic having a bandwidth large enough to measure the crack depth by frequency is radiated from the speaker 1 toward the target test body. By the test sound wave radiated from the speaker 1, the target test body 2
Inside the crack, the incident wave and the reflected wave interfere,
Resonance phenomenon occurs. Next, the microphone 5 receives the resonance sound wave inside the crack and converts the acoustic energy into electric energy. Then, based on the electric signal transmitted from the microphone 5, the frequency analysis device 4 measures the magnitude of each frequency component. Then, the frequency at which the amplitude shows a peak is detected as the resonance frequency, and the crack depth is calculated based on the resonance theory.
【0042】第3の実施の形態でも,共鳴周波数を分析
することによって第1の実施の形態と同様にひび割れ深
さを算出することができる。なお,放射試験音波をスイ
ープさせて観測する方法によっても同様にひび割れ深さ
を求めることができる。Also in the third embodiment, the crack depth can be calculated by analyzing the resonance frequency as in the first embodiment. Note that the crack depth can also be obtained in the same way by observing the sound waves emitted by the radiation test.
【0043】図11は,本発明の第4の実施の形態にお
けるひび割れ深さの計測方法の概要を示す図である。第
4の実施の形態においては,圧縮空気9を利用する。FIG. 11 is a diagram showing an outline of a crack depth measuring method according to the fourth embodiment of the present invention. In the fourth embodiment, compressed air 9 is used.
【0044】まず,対象試験体2のひび割れ内部に向け
て,ノズル8から圧縮空気9を吹き付ける。吹きつけた
圧縮空気9により,対象試験体2のひび割れ内部におい
て共鳴現象が生じる。次に,マイクロフォン5が,ひび
割れ内部の共鳴音波を受音し,その音響エネルギーを電
気エネルギーに変換する。そして,マイクロフォン5か
ら送信された電気信号に基づいて,周波数分析装置4が
各周波数成分の大きさを測定する。そして,振幅がピー
クを示す周波数を共鳴周波数として検出し,共鳴理論に
基づいて,ひび割れ深さを算出する。First, the compressed air 9 is blown from the nozzle 8 toward the inside of the crack of the test specimen 2. The blown compressed air 9 causes a resonance phenomenon inside the crack of the target test body 2. Next, the microphone 5 receives the resonance sound wave inside the crack and converts the acoustic energy into electric energy. Then, based on the electric signal transmitted from the microphone 5, the frequency analysis device 4 measures the magnitude of each frequency component. Then, the frequency at which the amplitude shows a peak is detected as the resonance frequency, and the crack depth is calculated based on the resonance theory.
【0045】図12に,40mm厚のコンクリート製敷石
板を割り,破断面を密着させ,下面を油土で閉じた非直
線的断面長の空隙部の開口と,溝深さ30mmのコンクリ
ートひび割れ試験体の開口に圧縮空気を吹き付け,発生
音を周波数分析した実験例を示す。図12に示すグラフ
のように,スピーカから試験音波を放射して観測したピ
ークと同じ周波数において,鈍化したピークが観測され
た。この結果から第4の実施の形態でも,共鳴周波数を
分析することによって第1の実施の形態のときよりもピ
ークが鈍化しているものの,第1の実施の形態と同様に
ひび割れ深さを算出することができることが確認され
た。FIG. 12 shows a concrete crack test with a 40 mm thick concrete paving slab, the fracture surfaces of which are adhered to each other, and the bottom surface of which is closed with oil soil to form a void having a non-linear section length and a groove depth of 30 mm. An example of an experiment in which compressed air was blown to the opening of the body and the generated sound was frequency analyzed is shown. As shown in the graph of FIG. 12, a blunted peak was observed at the same frequency as the peak observed by radiating the test sound wave from the speaker. From this result, in the fourth embodiment as well, although the peak becomes slower by analyzing the resonance frequency than in the first embodiment, the crack depth is calculated similarly to the first embodiment. It was confirmed that it can be done.
【0046】図13は,本発明の第5の実施の形態にお
けるひび割れ深さの計測方法の概要を示す図である。第
5の実施の形態においては,音響管を用いて試験音波を
放射し,音響管法によりひび割れ表面のインピーダンス
や吸音率を求め,この吸音率を測定することを通じて前
述した他の実施の形態と同様に共鳴周波数のピークと,
それによるひび割れ深さを推定する。FIG. 13 is a diagram showing an outline of a crack depth measuring method according to the fifth embodiment of the present invention. In the fifth embodiment, a test sound wave is radiated using an acoustic tube, the impedance and sound absorption coefficient of the cracked surface are obtained by the acoustic tube method, and the sound absorption coefficient is measured to compare with other embodiments described above. Similarly, the peak of the resonance frequency,
Estimate the resulting crack depth.
【0047】まず,対象試験体2のひび割れ表面を覗く
ように音響管10を垂直に立て,音響管10内のひび割
れ近傍に2個のマイクロフォン5A,5Bを僅かな距離
を離して配置する。音響管10の上部に配置したスピー
カー1からホワイトノイズ等の試験音波を放射して,マ
イクロフォン5A,5Bの出力を周波数分析器4に導き
音圧計測する。2つのマイクロフォン出力に時間遅れ等
の演算処理を行えば,対象試験体2の表面への入射音圧
と表面からの反射音圧の比率,すなわち音圧反射係数が
求められる。これから,ひび割れ表面の音響インピーダ
ンス(音響アドミッタンスの逆数)や吸音率が求められ
る。First, the acoustic tube 10 is erected vertically so as to look into the crack surface of the target test body 2, and two microphones 5A and 5B are arranged in the acoustic tube 10 in the vicinity of the crack with a slight distance therebetween. A test sound wave such as white noise is radiated from the speaker 1 arranged above the acoustic tube 10, the outputs of the microphones 5A and 5B are guided to the frequency analyzer 4, and the sound pressure is measured. By performing a calculation process such as a time delay on the outputs of the two microphones, the ratio of the sound pressure incident on the surface of the target test body 2 and the sound pressure reflected from the surface, that is, the sound pressure reflection coefficient is obtained. From this, the acoustic impedance (reciprocal of acoustic admittance) and sound absorption coefficient of the cracked surface can be obtained.
【0048】音圧反射係数をrとすれば,表面の音響イ
ンピーダンスZ,吸音率αは,
Z=(1+r)/(1−r),α=1−r2
となるので,この式によって求めることができる。If the sound pressure reflection coefficient is r, the acoustic impedance Z of the surface and the sound absorption coefficient α are Z = (1 + r) / (1-r), α = 1-r 2 be able to.
【0049】すなわち,音響管10の内部に2個のマイ
ロフォン5A,5Bを設置し,それぞれの点での音圧を
同時観測し,どちらか一方の音圧計測値に距離に相応す
る位相遅延演算を行って両者の差分を求めると,進行波
あるいは後退波成分が打ち消しあい,どちらか一方の成
分の除去が可能となる。ここから,ひび割れの共鳴現象
によって音圧反射係数の計算ができるようになる。この
ような音響管を用いた垂直入射吸音特性の測定法につい
ては,周知の技術である(参考文献:「騒音制御工学ハ
ンドブック」(社)日本騒音制御工学会編)。That is, two mylophones 5A and 5B are installed inside the acoustic tube 10, the sound pressure at each point is simultaneously observed, and the phase delay calculation corresponding to the distance to either one of the sound pressure measurement values. When the difference between the two is obtained by performing the above, the traveling wave or backward wave components cancel each other out, and either component can be removed. From this, it becomes possible to calculate the sound pressure reflection coefficient by the resonance phenomenon of cracks. The method of measuring the normal incidence sound absorption characteristics using such an acoustic tube is a well-known technique (reference: "Noise Control Engineering Handbook" (Company, Japan Society for Noise Control Engineering)).
【0050】共鳴現象によって吸音率が変化する理由
は,以下のとおりである。試験音波の放射によって対象
試験体2の内部に共鳴現象が生じると,空気粒子が激し
く運動する。その結果,ひび割れ表面付近に粘性摩擦が
生じ,運動エネルギーの消費(熱エネルギーへの変換)
によって吸音効果が現れ,吸音率は共鳴周波数でピーク
を示す。そこで,この周波数特性から吸音率の高いピー
クを測定することを通じて,前述した実施の形態と同様
に分析することにより,ひび割れ深さが推定可能とな
る。The reason why the sound absorption coefficient changes due to the resonance phenomenon is as follows. When the resonance phenomenon occurs inside the target test body 2 due to the emission of the test sound wave, the air particles move violently. As a result, viscous friction occurs near the surface of the crack and consumption of kinetic energy (conversion into heat energy)
The sound absorption effect appears due to, and the sound absorption coefficient peaks at the resonance frequency. Therefore, the crack depth can be estimated by measuring a peak having a high sound absorption coefficient from this frequency characteristic and performing the same analysis as in the above-described embodiment.
【0051】[0051]
【発明の効果】本発明により,構造物に生じたひび割れ
内部に生じた共鳴音波の共鳴周波数を捉えることが可能
となり,かかる共鳴周波数を分析し,共鳴理論を適用す
ることを通じてひび割れ深さを計測することができる。
また,基本共鳴周波数に加えて,より高次の共鳴周波数
も検知して計測の確度を向上することができる。According to the present invention, it is possible to detect the resonance frequency of the resonance sound wave generated inside the crack generated in the structure, analyze the resonance frequency, and measure the crack depth by applying the resonance theory. can do.
In addition to the fundamental resonance frequency, higher order resonance frequencies can be detected to improve the accuracy of measurement.
【図1】第1の実施の形態におけるひび割れ深さ計測方
法の概要を示す図である。FIG. 1 is a diagram showing an outline of a crack depth measuring method according to a first embodiment.
【図2】周波数分析装置の構成図である。FIG. 2 is a configuration diagram of a frequency analysis device.
【図3】第1の実施の形態における実験例を示すグラフ
である。FIG. 3 is a graph showing an experimental example in the first embodiment.
【図4】第1の実施の形態における実験例を示すグラフ
である。FIG. 4 is a graph showing an experimental example in the first embodiment.
【図5】第1の実施の形態における実験例を示すグラフ
である。FIG. 5 is a graph showing an experimental example in the first embodiment.
【図6】第1の実施の形態における実験例を示すグラフ
である。FIG. 6 is a graph showing an experimental example in the first embodiment.
【図7】第1の実施の形態における実験例を示すグラフ
である。FIG. 7 is a graph showing an experimental example in the first embodiment.
【図8】周波数分析装置の構成図である。FIG. 8 is a configuration diagram of a frequency analysis device.
【図9】第2の実施の形態におけるひび割れ深さ計測方
法の概要を示す図である。FIG. 9 is a diagram showing an outline of a crack depth measuring method according to the second embodiment.
【図10】第3の実施の形態におけるひび割れ深さ計測
方法の概要を示す図である。FIG. 10 is a diagram showing an outline of a crack depth measuring method according to a third embodiment.
【図11】第4の実施の形態におけるひび割れ深さ計測
方法の概要を示す図である。FIG. 11 is a diagram showing an outline of a crack depth measuring method according to a fourth embodiment.
【図12】第4の実施の形態における実験例を示すグラ
フである。FIG. 12 is a graph showing an experimental example in the fourth embodiment.
【図13】第5の実施の形態におけるひび割れ深さ計測
方法の概要を示す図である。FIG. 13 is a diagram showing an outline of a crack depth measuring method according to a fifth embodiment.
【図14】閉管における共鳴音波の一例を示す図であ
る。FIG. 14 is a diagram showing an example of resonance sound waves in a closed tube.
【図15】開管における共鳴音波の一例を示す図であ
る。FIG. 15 is a diagram showing an example of resonance sound waves in an open tube.
【図16】共鳴現象を示すグラフである。FIG. 16 is a graph showing a resonance phenomenon.
1 スピーカ 2 対象試験体 3 粒子速度センサー 4 周波数分析装置 5 マイクロフォン 6 周波数分析装置 7 カバー 8 ノズル 9 圧縮空気 10 音響管 41 A/D変換器 42 A/D変換器 43 フーリエ変換部 44 フーリエ変換部 45 音響アドミッタンス計算部 46 周波数情報出力部 60 周波数制御部 61 スピーカ出力周波数制御部 62 D/A変換器 63 A/D変換器 64 周波数情報出力部 1 speaker 2 Target specimen 3 Particle velocity sensor 4 Frequency analyzer 5 microphones 6 Frequency analyzer 7 cover 8 nozzles 9 compressed air 10 sound tube 41 A / D converter 42 A / D converter 43 Fourier transform unit 44 Fourier transform unit 45 Acoustic admittance calculator 46 Frequency information output section 60 Frequency controller 61 Speaker output frequency controller 62 D / A converter 63 A / D converter 64 Frequency information output section
───────────────────────────────────────────────────── フロントページの続き (72)発明者 安岡 博人 千葉県流山市駒木518−1 三井建設株式 会社技術研究所内 (72)発明者 岩本 毅 千葉県流山市駒木518−1 三井建設株式 会社技術研究所内 Fターム(参考) 2F068 AA24 BB01 BB09 CC11 FF23 GG05 GG09 QQ05 QQ06 QQ10 2G047 AA10 BC04 BC07 BC18 EA10 GA18 GF11 GG09 GG12 ─────────────────────────────────────────────────── ─── Continued front page (72) Inventor Hiroto Yasuoka 518-1 Komagaki, Nagareyama-shi, Chiba Mitsui Construction Co., Ltd. Company Technology Research Center (72) Inventor Takeshi Iwamoto 518-1 Komagaki, Nagareyama-shi, Chiba Mitsui Construction Co., Ltd. Company Technology Research Center F term (reference) 2F068 AA24 BB01 BB09 CC11 FF23 GG05 GG09 QQ05 QQ06 QQ10 2G047 AA10 BC04 BC07 BC18 EA10 GA18 GF11 GG09 GG12
Claims (6)
であって,対象試験体に試験音波を放射するステップ
と,対象試験体のひび割れの表面入口の空気粒子の振動
速度を測定するステップと,測定した振動速度に基づい
て,対象試験体のひび割れ内部に生じた共鳴音波の共鳴
周波数を分析するステップと,分析した共鳴周波数から
ひび割れ深さを算出または推定するための情報を出力す
るステップとを有することを特徴とする構造物に生じた
ひび割れ深さの計測方法。1. A method for measuring the depth of cracks in a structure, the method comprising: radiating a test sound wave to a target test body; and measuring the vibration velocity of air particles at the surface entrance of the crack of the target test body. And a step of analyzing the resonance frequency of the resonance sound wave generated inside the crack of the target test body based on the measured vibration velocity, and a step of outputting information for calculating or estimating the crack depth from the analyzed resonance frequency. A method for measuring a crack depth generated in a structure, characterized by having.
であって,対象試験体に試験音波を放射するステップ
と,対象試験体のひび割れ内部に生じた共鳴音波を受音
するステップと,受音した共鳴音波の共鳴周波数を分析
するステップと,分析した共鳴周波数からひび割れ深さ
を算出または推定するための情報を出力するステップと
を有することを特徴とする構造物に生じたひび割れ深さ
の計測方法。2. A method of measuring a crack depth generated in a structure, comprising: radiating a test sound wave to a target test body; and receiving a resonance sound wave generated inside the crack of the target test body. Crack depth generated in a structure, characterized by having a step of analyzing the resonance frequency of the received resonance sound wave and a step of outputting information for calculating or estimating the crack depth from the analyzed resonance frequency. Measurement method.
であって,対象試験体に圧縮空気を吹き付けるステップ
と,対象試験体のひび割れ内部に生じた共鳴音波を受音
するステップと,受音した共鳴音波の共鳴周波数を分析
するステップと,分析した共鳴周波数からひび割れ深さ
を算出または推定するための情報を出力するステップと
を有することを特徴とする構造物に生じたひび割れ深さ
の計測方法。3. A method for measuring a crack depth generated in a structure, comprising: blowing compressed air to a target test body; receiving a resonance sound wave generated inside the crack of the target test body; A crack depth generated in a structure, characterized by having a step of analyzing the resonance frequency of the sounded resonance sound wave and a step of outputting information for calculating or estimating the crack depth from the analyzed resonance frequency. Measuring method.
であって,対象試験体に試験音波を放射する手段と,対
象試験体のひび割れの表面入口の空気粒子の振動速度を
測定する手段と,測定した振動速度に基づいて,対象試
験体のひび割れ内部に生じた共鳴音波の共鳴周波数を分
析する手段と,分析した共鳴周波数からひび割れ深さを
算出または推定するための情報を出力する手段とを備え
ることを特徴とする構造物に生じたひび割れ深さの計測
装置。4. A device for measuring a crack depth generated in a structure, comprising means for radiating a test sound wave to a target test body and means for measuring the vibration velocity of air particles at the surface entrance of the crack of the target test body. And means for analyzing the resonance frequency of the resonance sound wave generated inside the crack of the target test body based on the measured vibration velocity, and means for outputting information for calculating or estimating the crack depth from the analyzed resonance frequency. An apparatus for measuring a crack depth generated in a structure, comprising:
であって,対象試験体に試験音波を放射する手段と,対
象試験体のひび割れ内部に生じた共鳴音波を受音する手
段と,受音した共鳴音波の共鳴周波数を分析する手段
と,分析した共鳴周波数からひび割れ深さを算出または
推定するための情報を出力する手段とを備えることを特
徴とする構造物に生じたひび割れ深さの計測装置。5. A device for measuring a crack depth generated in a structure, comprising means for radiating a test sound wave to a target test body, and means for receiving a resonance sound wave generated inside the crack of the target test body. Crack depth in a structure, characterized by comprising means for analyzing the resonance frequency of the received resonance sound wave and means for outputting information for calculating or estimating the crack depth from the analyzed resonance frequency. Measuring device.
であって,対象試験体に圧縮空気を吹き付ける手段と,
対象試験体のひび割れ内部に生じた共鳴音波を受音する
手段と,受音した共鳴音波の共鳴周波数を分析する手段
と,分析した共鳴周波数からひび割れ深さを算出または
推定するための情報を出力する手段とを備えることを特
徴とする構造物に生じたひび割れ深さの計測装置。6. A device for measuring a crack depth generated in a structure, which comprises means for blowing compressed air to a target test body,
A means for receiving the resonance sound wave generated inside the crack of the target test body, a means for analyzing the resonance frequency of the received resonance sound wave, and the output of information for calculating or estimating the crack depth from the analyzed resonance frequency. An apparatus for measuring a crack depth generated in a structure, comprising:
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