JP3523806B2 - Defect inspection method in concrete structure - Google Patents
Defect inspection method in concrete structureInfo
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- JP3523806B2 JP3523806B2 JP17489899A JP17489899A JP3523806B2 JP 3523806 B2 JP3523806 B2 JP 3523806B2 JP 17489899 A JP17489899 A JP 17489899A JP 17489899 A JP17489899 A JP 17489899A JP 3523806 B2 JP3523806 B2 JP 3523806B2
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- Prior art keywords
- concrete structure
- elastic wave
- virtual point
- section
- frequency
- Prior art date
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- Measurement Of Mechanical Vibrations Or Ultrasonic Waves (AREA)
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、コンクリート構造
物中の欠陥検査方法に関し、特に、例えばＰＣ橋梁等の
ＰＣ構造物における補強材周りのグラウト充填不良など
による空洞を、インパクトエコー法により非破壊的に検
査するコンクリート構造物中の欠陥検査方法に関するも
のである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of inspecting defects in a concrete structure, and more particularly, to non-destructive cavities due to defective grout filling around a reinforcing material in a PC structure such as a PC bridge by an impact echo method. The present invention relates to a method for inspecting defects in a concrete structure that is to be inspected.
【０００２】[0002]
【従来の技術及びその課題】例えば、ポストテンション
工法によるＰＣ構造物においては、予め孔を開けた状態
で固化させたコンクリート構造物の該孔に、鋼線や鋼棒
等の補強材を挿通して該補強材にテンションを掛けた
後、前記孔内にグラウトを充填させて固化させることに
より、ＰＣ構造物全体に圧縮力を付与して強度の向上を
図っている。2. Description of the Related Art For example, in a PC structure by the post-tensioning method, a reinforcing material such as a steel wire or a steel rod is inserted into the hole of a concrete structure which has been solidified in a state where a hole is previously formed. After applying tension to the reinforcing material, the hole is filled with grout to be solidified, so that a compressive force is applied to the entire PC structure to improve the strength.
【０００３】ところが、グラウトを補強材周りに充分に
充填させることは困難な作業であり、不測にグラウトの
充填が不十分な場合が生じる。このような場合には、Ｐ
Ｃ構造物における設計当初の強度が得られず、また補強
材の腐食防止の観点からも不都合が生じるため、施工後
の構造物におけるグラウトの充填状況を非破壊的に検査
する必要性が生じる。However, it is a difficult task to sufficiently fill the grout around the reinforcing material, and there are cases in which the grout is unexpectedly insufficiently filled. In such a case, P
Since the strength of the C structure at the time of the initial design cannot be obtained and inconvenience also occurs from the viewpoint of corrosion prevention of the reinforcing material, it becomes necessary to non-destructively inspect the grout filling state in the structure after construction.
【０００４】かかるコンクリート構造物中に存在する空
洞を非破壊的に検査する方法としては、従来よりインパ
クトエコー法が注目されている。このインパクトエコー
法とは、鋼球を対象物に落下或いは打撃することで弾性
波を入力し、その応答波形から部材内部の空洞の有無な
どを検査する方法であり、例えばＰＣ構造物においてグ
ラウト充填不良などによる空洞が存在した場合、該ＰＣ
構造物に鋼球を落下或いは打撃することで弾性波を入力
すると、該弾性波中の特定の周波数の振動はＰＣ構造物
内のコンクリートと空洞との境界面において反射し、応
答波形をスペクトル解析して得られる周波数と振幅との
関係を示すスペクトルにおいて、この反射した特定周波
数の振動がピークとなって現れることに着目した検査方
法である。As a method of nondestructively inspecting the cavities existing in such a concrete structure, the impact echo method has hitherto attracted attention. The impact echo method is a method of inputting an elastic wave by dropping or hitting a steel ball on an object and inspecting the presence or absence of a cavity inside the member from the response waveform, for example, grout filling in a PC structure. If there is a cavity due to a defect, etc., the PC
When an elastic wave is input by dropping or hitting a steel ball on the structure, vibration of a specific frequency in the elastic wave is reflected at the boundary surface between the concrete and the cavity in the PC structure, and the response waveform is spectrally analyzed. This is an inspection method that focuses on the fact that the reflected vibration of the specific frequency appears as a peak in the spectrum showing the relationship between the frequency and the amplitude.
【０００５】即ち、インパクトエコー法によれば、空洞
での反射によるピーク周波数ｆＶｏ ｉｄは、以下の式で
表せるとされている。
ｆＶｏｉｄ＝０．９６ＣＰ／２ｄ ・・・・・（１）
ここで、ＣＰは弾性波の伝播速度、ｄは弾性波入力箇所
から空洞までのかぶり深さである。但し、上記式（１）
中に見られる係数０．９６は、弾性波の補正係数とされ
ており、インパクトエコー法の原理と関連するものでは
ない。また、空洞での反射の影響が２波長で現れる場
合、ピーク周波数は、
ｆＶｏｉｄ＝ＣＰ／ｄ ・・・・・（２）
となる。That is, according to the impact echo method, the peak frequency f Vo id due to reflection in the cavity can be expressed by the following equation. f Void = 0.96C P / 2d (1) Here, C P is the propagation velocity of the elastic wave, and d is the fog depth from the elastic wave input point to the cavity. However, the above formula (1)
The coefficient 0.96 seen therein is a correction coefficient for elastic waves and is not related to the principle of the impact echo method. When the influence of reflection in the cavity appears at two wavelengths, the peak frequency is f Void = C P / d (2).
【０００６】そこで、ＰＣ構造物に弾性波を入力した
際、その応答波形をスペクトル解析して得られたスペク
トル中に、上記式（１）及び（２）で求められた周波数
においてピークが存在した場合には、そのＰＣ構造物の
補強材周りには、グラウト充填不良などによる空洞が存
在すると判断できる。Therefore, when an elastic wave is input to the PC structure, a peak exists at the frequency obtained by the above equations (1) and (2) in the spectrum obtained by spectral analysis of the response waveform. In this case, it can be judged that there is a cavity around the reinforcing material of the PC structure due to defective grout filling or the like.
【０００７】しかしながら、本発明者らの試験・研究に
よると、上記対象物に弾性波を入力した際の応答波形を
スペクトル解析して得られるスペクトル中には、上記空
洞の影響と思われるピークも見られるが、他のピークも
多く存在し、明瞭に空洞の有無を検出できるとは言い難
い方法であった。また、上記方法は、着目する周波数を
決定する必要があることから、空洞が存在すると想定さ
れる位置、例えば補強材の位置を予め正確に把握してい
ることが必要となり、検査断面中の任意の位置に存在す
る亀裂などによる空洞を検出するには不向きな方法であ
った。However, according to the tests and studies by the present inventors, in the spectrum obtained by spectrally analyzing the response waveform when an elastic wave is input to the object, there is a peak that is considered to be due to the cavity. Although it can be seen, many other peaks were present, and it was difficult to say that the presence or absence of cavities could be clearly detected. Further, in the above method, since it is necessary to determine the frequency of interest, it is necessary to accurately grasp the position where the cavity is supposed to exist, for example, the position of the reinforcing material in advance. It was an unsuitable method for detecting cavities due to cracks existing at the position.
【０００８】本発明は、上述した従来のインパクトエコ
ー法を利用した空洞検査の方法が有する課題に鑑み成さ
れたものであって、その目的は、検査断面中の任意の位
置に存在する空洞等の欠陥の有無を明瞭に判断できるコ
ンクリート構造物中の欠陥検査方法を提供することにあ
る。The present invention has been made in view of the problems of the above-described conventional cavity inspection method using the impact echo method, and its purpose is to provide a cavity or the like existing at an arbitrary position in the inspection cross section. The object of the present invention is to provide a method for inspecting defects in a concrete structure that can clearly determine the presence or absence of defects.
【０００９】[0009]
【課題を解決するための手段】本発明者らは、上記した
目的を達成すべく試験・研究を重ねた結果、対象物に弾
性波を入力した際の応答波形から、検査断面中のどの位
置からの反射の影響が多く含まれているかを検出するこ
とができれば、検査断面中の任意の位置に存在する空洞
等の欠陥の有無を明瞭に判断できるとの知見に基づき、
本発明を完成させた。As a result of repeated tests and studies to achieve the above-mentioned object, the inventors of the present invention have determined which position in an inspection cross section from the response waveform when an elastic wave is input to an object. Based on the knowledge that it is possible to clearly determine the presence or absence of defects such as cavities present at any position in the inspection cross section, if it is possible to detect whether the influence of reflection from
The present invention has been completed.
【００１０】即ち、本発明は、鋼球を落下或いは打撃す
ることによりコンクリート構造物の表面から弾性波を入
力し、その時のコンクリート構造物からの応答波形から
コンクリート構造物中の欠陥の有無を検査するインパク
トエコー法を用いたコンクリート構造物中の欠陥検査方
法において、上記応答波形をスペクトル解析して周波数
と振幅との関係を示すスペクトルとすると共に、上記コ
ンクリート構造物の検査断面中に複数個の仮想点を想定
し、該仮想点において反射する弾性波の理論周波数を各
々の仮想点について算出し、この理論周波数に対応する
上記スペクトル中の周波数の振幅値を各々の仮想点にお
いて求め、この各々の仮想点における振幅値を比較する
ことによりコンクリート構造物中の欠陥の有無を判断す
ることとした。That is, the present invention inputs an elastic wave from the surface of a concrete structure by dropping or hitting a steel ball, and inspects the presence or absence of defects in the concrete structure from the response waveform from the concrete structure at that time. In the defect inspection method in the concrete structure using the impact echo method, in the spectral analysis of the response waveform and a spectrum showing the relationship between frequency and amplitude, a plurality of in the inspection cross section of the concrete structure. Assuming a virtual point, the theoretical frequency of the elastic wave reflected at the virtual point is calculated for each virtual point, and the amplitude value of the frequency in the spectrum corresponding to this theoretical frequency is obtained at each virtual point. It was decided to judge the presence or absence of defects in the concrete structure by comparing the amplitude values at the virtual points.
【００１１】上記した本発明にかかるコンクリート構造
物中の欠陥検査方法によれば、コンクリート構造物に弾
性波を入力した際の応答波形をスペクトル解析して得ら
れた周波数と振幅との関係を示すスペクトルが、検査断
面中のどの位置からの反射の影響を多く含んでいるかを
各仮想点における振幅値を比較することにより検出する
ことができるため、検査断面中の任意の位置に存在する
空洞等の欠陥の有無を明瞭に判断できる。According to the above-described defect inspection method for a concrete structure according to the present invention, the relationship between the frequency and the amplitude obtained by spectrally analyzing the response waveform when an elastic wave is input to the concrete structure is shown. It can be detected by comparing the amplitude value at each virtual point from which position in the inspection cross section the spectrum contains the influence of reflection, so the cavity etc. existing at any position in the inspection cross section can be detected. The presence or absence of defects can be clearly determined.
【００１２】ここで、上記本発明において、検査断面中
に想定する複数個の仮想点において各々反射する弾性波
の理論周波数としては、弾性波の入力点から仮想点を経
て応答波形の検出点に至るまでの距離をＲとした場合、
ｆ１＝ＣＰ／（Ｒ／２）、ｆ２＝ＣＰ／Ｒ、ｆ３＝ＣＰ
／２Ｒ、ｆ４＝ＣＰ／３Ｒ、・・・・
で求められる複数個の周波数とすると共に、この複数個
の理論周波数の各々に対応する上記スペクトル中の周波
数の振幅値の合計を各々の仮想点において求め、この各
々の仮想点における振幅値の合計を比較することにより
コンクリート構造物中の欠陥の有無を判断することが好
ましい。これは、応答波形をスペクトル解析して得られ
る周波数と振幅との関係を示すスペクトル中には、空洞
部による反射の影響が１波長、２波長、或いはそれ以上
の波長で現れるものが存在すると考えられるため、各仮
想点について反射する弾性波の理論周波数も、これらの
１波長で現れる周波数、２波長で現れる周波数、或いは
それ以上の波長で現れる周波数を各々求め、この複数個
の理論周波数の各々に対応する上記スペクトル中の周波
数の振幅値の合計を各々の仮想点における反射の影響と
捉えることが好ましいためである。なお、上記式中ＣＰ
は、弾性波のコンクリート構造物中における伝播速度で
ある。Here, in the above-mentioned present invention, the theoretical frequency of the elastic wave reflected at each of a plurality of virtual points assumed in the inspection cross section is from the input point of the elastic wave to the detection point of the response waveform via the virtual point. When the distance to reach is R, f 1 = C P / (R / 2), f 2 = C P / R, f 3 = C P
/ 2R, f 4 = C P / 3R, ..., And a plurality of frequencies are obtained, and the sum of the amplitude values of the frequencies in the spectrum corresponding to each of the plurality of theoretical frequencies is calculated. It is preferable to determine whether or not there is a defect in the concrete structure by determining at virtual points and comparing the sum of the amplitude values at each virtual point. It is considered that there is a spectrum showing the relationship between frequency and amplitude obtained by spectral analysis of the response waveform, in which the influence of reflection by the cavity appears at one wavelength, two wavelengths, or more wavelengths. Therefore, for the theoretical frequencies of the elastic waves reflected at each virtual point, the frequencies appearing at one wavelength, the frequencies appearing at two wavelengths, or the frequencies appearing at more wavelengths are obtained, and each of the plurality of theoretical frequencies is obtained. This is because it is preferable to regard the sum of the amplitude values of the frequencies in the spectrum corresponding to the above as the influence of the reflection at each virtual point. In the above formula, C P
Is the propagation velocity of the elastic wave in the concrete structure.
【００１３】また、上記本発明において、コンクリート
構造物の検査断面中に想定する複数個の仮想点として
は、空洞が存在すると想定される位置及びその周囲の複
数点としても良いが、検査断面を複数個に等分割、例え
ば検査断面を１平方センチメートルの正方形に分割し、
その各々の分割断面の中心を仮想点とすることが好まし
い。これは、このように検査断面中に複数個の仮想点を
想定すると、検査断面中のいずれの箇所からの反射の影
響が大きいかを満遍なく検出することができ、想像に反
した任意の位置に存在する亀裂等による空洞の有無も明
瞭に判断できるために好ましい。Further, in the present invention described above, the plurality of virtual points assumed in the inspection cross section of the concrete structure may be a position where a cavity is assumed to exist and a plurality of points around the position. Divide into multiple equal parts, for example, divide the inspection cross section into squares of 1 square centimeter,
It is preferable that the center of each of the divided cross sections be a virtual point. This means that if multiple virtual points are assumed in the inspection cross-section, it is possible to detect uniformly from which point in the inspection cross-section the influence of reflection is great, and it is possible to detect at any position that is unimaginable. It is preferable because the presence or absence of cavities due to existing cracks can be clearly determined.
【００１４】さらに、本発明において、上記各々の仮想
点における振幅値の比較方法としては、振幅値そのもの
を数値的に比較しても良いが、各々の仮想点における振
幅値の大小を視覚的に把握し得る状態、例えば検査断面
上に各々の仮想点における振幅値を３Ｄグラフ化する、
或いは等高線グラフ化することにより行うことが好まし
い。これは、視覚的に各々の仮想点における振幅値の大
小が把握できれば、より明確に検査断面中における空洞
の有無を判断できるために好ましい。Further, in the present invention, as a method of comparing the amplitude values at the respective virtual points, the amplitude values themselves may be compared numerically, but the magnitude of the amplitude values at the respective virtual points may be visually compared. A recognizable state, for example, a 3D graph of the amplitude value at each virtual point on the inspection cross section,
Alternatively, it is preferably performed by making a contour graph. This is preferable because it is possible to more clearly determine the presence or absence of a cavity in the inspection cross section if the magnitude of the amplitude value at each virtual point can be visually recognized.
【００１５】[0015]
【試験例】以下、上記した本発明にかかるコンクリート
構造物中の欠陥検査方法を見出した試験につき説明す
る。[Test Example] A test for finding a method for inspecting defects in a concrete structure according to the present invention will be described below.
【００１６】（使用供試体）図１に示したように、２５
０×２５０×１０００ｍｍの角柱供試体に、直径３０ｍ
ｍ、長さ７５０ｍｍのシース管を用いて空洞部を作成
し、シースによる空洞部をグラウト未充填部、シースが
ない部分をグラウト充填部と仮定した供試体を使用し
た。この供試体の配合組成は、表１に示した通りであ
る。(Sample used) As shown in FIG.
0m x 250mm x 1000mm prismatic specimen, diameter 30m
A cavity was created using a sheath tube having a length of m and a length of 750 mm, and the cavity was defined as a grout-unfilled portion and a sheath-free portion was used as a grout-filled portion. The compounding composition of this sample is as shown in Table 1.
【００１７】[0017]
【表１】
なお、粗骨材の最大寸法は２０ｍｍであり、表１のスラ
ンプは打設時における実測値である。[Table 1] The maximum size of the coarse aggregate is 20 mm, and the slump in Table 1 is a measured value at the time of placing.
【００１８】供試体は、打設後２４時間空気中に放置し
た後に脱型を行い、２８日間恒温室で水中養生した後、
試験に使用した。供試体の２８日材令での力学的特性を
表２に示す。The test piece was left in the air for 24 hours after casting, demolded, and cured in water in a thermostatic chamber for 28 days.
Used for testing. Table 2 shows the mechanical properties of the specimens at 28-day age.
【００１９】[0019]
【表２】 [Table 2]
【００２０】（試験の概要）本試験では、上記供試体に
高周波数を含む外力を入力するため、飛翔体衝突のイン
パクト試験を行った。(Outline of Test) In this test, an impact test of a flying object collision was carried out in order to input an external force including a high frequency to the test piece.
【００２１】飛翔体は、図２に示したような直径１０ｍ
ｍ、長さ２０ｍｍのアルミ弾を使用し、この飛翔体の先
端と供試体表面との距離を一定にし、図３に示した供試
体の断面Ａ及び断面Ｂの各々の位置において、コンプレ
ッサーの空気圧により内径１１ｍｍのアルミパイプ内か
ら飛翔体を発射させた。この際、供試体に入力される周
波数の上限は、４００００Ｈｚ程度である。The flying body has a diameter of 10 m as shown in FIG.
The air pressure of the compressor at each position of the cross section A and the cross section B of the test piece shown in FIG. 3 is made by using an aluminum bullet of m and a length of 20 mm to keep the distance between the tip of the flying object and the test piece surface constant. A projectile was fired from inside an aluminum pipe having an inner diameter of 11 mm. At this time, the upper limit of the frequency input to the sample is about 40,000 Hz.
【００２２】飛翔体衝突により入力された衝撃は、図３
に示したように供試体表面に設置された加速度計で電気
信号に変換され、この変換された電気信号をある時間間
隔でＮ個サンプリングしたものを波形記録装置にデジタ
ル量として記録させ、さらにこのデーターをパーソナル
コンピュータで記録及び高速フーリエ変換（スペクトル
解析）して周波数と振幅との関係を示すスペクトルを求
めた。The impact input by the collision of the flying object is shown in FIG.
As shown in Fig. 4, the accelerometer installed on the surface of the specimen converts it into an electric signal, and the converted electric signal is sampled N times at a certain time interval and recorded as a digital amount in the waveform recording device. The data was recorded by a personal computer and subjected to fast Fourier transform (spectral analysis) to obtain a spectrum showing the relationship between frequency and amplitude.
【００２３】（データーの解析方法）インパクトエコー
法によれば、板厚によるピーク周波数ｆＴ、空洞での反
射によるピーク周波数ｆＶｏｉｄは、各々以下の式で表
せる。
ｆＴ＝０．９６ＣＰ／２Ｔ ・・・・・（ａ）
ｆＶｏｉｄ＝０．９６ＣＰ／２ｄ ・・・・・（ｂ）
ここで、ＣＰは弾性波の伝播速度、Ｔは供試体の板厚、
ｄは弾性波入力箇所からシースまでのかぶり深さであ
る。また、空洞での反射の影響が２波長で現れる場合、
ピーク周波数は、
ｆＶｏｉｄ＝ＣＰ／ｄ ・・・・・（ｃ）
となる。(Data Analysis Method) According to the impact echo method, the peak frequency f T due to the plate thickness and the peak frequency f Void due to reflection at the cavity can be expressed by the following equations. f T = 0.96C P / 2T (a) f Void = 0.96C P / 2d (b) where C P is the propagation velocity of elastic waves and T is the specimen Thickness of the
d is the fog depth from the elastic wave input portion to the sheath. Also, if the effect of reflection in the cavity appears at two wavelengths,
The peak frequency is f Void = C P / d (c).
【００２４】ここで、本試験において使用した供試体で
は、Ｔ＝０．２５ｍ、ｄ＝０．１１２８ｍ、弾性波の伝
播速度ＣＰ＝４４９６ｍ／ｓである。よって、上記
（ａ），（ｂ），（ｃ）式よりｆＴ＝８６３２Ｈｚ、ｆ
Ｖｏｉｄ＝１９１３１Ｈｚ、３９８５８Ｈｚ付近にスペ
クトルピークが現れると考えられる。Here, in the sample used in this test, T = 0.25 m, d = 0.1128 m, and the propagation velocity C P of elastic wave = 4496 m / s. Therefore, from the above equations (a), (b), (c), f T = 8632Hz, f
It is considered that a spectral peak appears near Void = 19131 Hz, 39858 Hz.
【００２５】図４に、断面Ａ、Ｂそれぞれで計測した波
形を示す。図４に示した波形の形状のみからは、シース
空洞による差異を確認することはできない。そこで、図
４に示す波形を、高速フーリエ変換（スペクトル解析）
することにより周波数と振幅との関係を示すスペクトル
としたものを図５に示す。図５に示したスペクトルにお
いて、断面Ａ、Ｂ両方に８０００Ｈｚ付近にスペクトル
ピークが見られ、これがｆＴであると考えられる。また
断面Ａでは、４００００Ｈｚ付近に若干のスペクトルピ
ークが見られ、これがｆＶｏｉｄに相当すると考えられ
る。ただし、ｆＶｏｉｄ＝１９１３１Ｈｚは明確ではな
い。FIG. 4 shows waveforms measured at the cross sections A and B, respectively. Differences due to the sheath cavity cannot be confirmed only from the waveform shape shown in FIG. Therefore, the waveform shown in FIG. 4 is transformed into a fast Fourier transform (spectral analysis).
FIG. 5 shows a spectrum showing the relationship between the frequency and the amplitude. In the spectrum shown in FIG. 5, spectral peaks are seen near 8000 Hz in both cross sections A and B, which is considered to be f T. Further, in the cross section A, a slight spectrum peak is observed near 40,000 Hz, which is considered to correspond to f Void . However, f Void = 19131 Hz is not clear.
【００２６】次に、スペクトルピークが、断面のどの位
置からの反射の影響を多く含んでいるのかを検討した。Next, it was examined from which position of the cross section the spectrum peak includes many influences of reflection.
【００２７】この方法は、検査断面Ａ及びＢを、各々１
平方センチメートル×６２５個の要素に区切り、図６に
示したように入力点からある要素の中心を経て出力点に
至るまでの距離をＲ＝ｒ１＋ｒ２とすると、その要素の
中心で反射する弾性波の理論周波数は、
ｆ１＝ＣＰ／（Ｒ／２）、ｆ２＝ＣＰ／Ｒ、ｆ３＝ＣＰ
／２Ｒ、ｆ４＝ＣＰ／３Ｒ、・・・
となる。そこで、この各理論周波数の各々に対応する上
記スペクトル中の周波数の振幅値の合計を各々の要素の
中心において求め、この各々の要素の中心における振幅
値の合計を比較した。なお、シース空洞による影響の検
出が目的のため、ｆｎは板厚によるピーク周波数ｆＴよ
り大きいもののみを考慮した。In this method, the inspection cross sections A and B are each set to 1
When the distance from the input point to the output point via the center of a certain element as shown in FIG. 6 is divided into square centimeters × 625 elements and R = r 1 + r 2 , the elasticity reflected at the center of the element The theoretical frequencies of the waves are: f 1 = C P / (R / 2), f 2 = C P / R, f 3 = C P
/ 2R, f 4 = C P / 3R, ... Therefore, the sum of the amplitude values of the frequencies in the spectrum corresponding to each of the theoretical frequencies was obtained at the center of each element, and the sum of the amplitude values at the center of each element was compared. Note that, for the purpose of detecting the influence of the sheath cavity, only f n larger than the peak frequency f T due to the plate thickness was considered.
【００２８】各々の要素の中心における振幅値の合計の
大小を視覚的に把握し得る状態、即ち検査断面上に各々
の要素の中心における振幅値を等高線グラフ化した結果
を図７に示す。図７より、断面Ａではシース付近におい
て明らかなピークの突出が見られ、シース空洞による反
射の影響が確認できた。FIG. 7 shows a result in which the magnitude of the total amplitude value at the center of each element can be visually grasped, that is, the amplitude value at the center of each element is plotted on a contour line on the inspection cross section. From FIG. 7, a clear peak protrusion was seen in the vicinity of the sheath in the cross section A, and the influence of reflection by the sheath cavity was confirmed.
【００２９】（結論）上記した試験により、供試体に弾
性波を入力した際の応答波形をスペクトル解析して得ら
れるスペクトル中には、シースによる空洞の影響と思わ
れるピークも見られるが、他のピークも多く存在するた
めに明瞭に検出されているとは言い難く、従来の応答波
形をスペクトル解析して得られるスペクトルのみでは、
シース空洞の有無を明確に判断することは困難である。
しかし、検査断面中に複数個の仮想点を想定し、該仮想
点において反射する弾性波の理論周波数を各々の仮想点
について算出し、この理論周波数に対応する上記スペク
トル中の周波数の振幅値を各々の仮想点において求め、
この各々の仮想点における振幅値を比較することとする
と、シースによる空洞での反射の影響を確認することが
でき、シース空洞の有無を明瞭に判断できるとの結論に
達した。(Conclusion) In the spectrum obtained by the spectrum analysis of the response waveform when the elastic wave is input to the specimen by the above-mentioned test, there are peaks which are considered to be due to the cavity due to the sheath. It is hard to say that it is clearly detected because there are many peaks of, and only the spectrum obtained by spectrum analysis of the conventional response waveform,
It is difficult to clearly determine the presence or absence of a sheath cavity.
However, assuming a plurality of virtual points in the inspection cross section, the theoretical frequency of the elastic wave reflected at the virtual points is calculated for each virtual point, and the amplitude value of the frequency in the spectrum corresponding to this theoretical frequency is calculated. Obtained at each virtual point,
By comparing the amplitude values at each of these virtual points, it was concluded that the effect of the reflection of the sheath by the cavity can be confirmed and the presence or absence of the sheath cavity can be clearly determined.
【００３０】[0030]
【発明の効果】以上、説明した本発明にかかるコンクリ
ート構造物中の欠陥検査方法によれば、検査部位におけ
る空洞或いは亀裂等の欠陥の有無を、非破壊的に容易に
判断できる効果がある。As described above, according to the defect inspection method for a concrete structure according to the present invention as described above, the presence or absence of defects such as cavities or cracks at the inspection site can be easily determined in a non-destructive manner.
【図１】本発明にかかる欠陥検査方法を見出す試験にお
いて使用したコンクリート構造物を示した図である。FIG. 1 is a view showing a concrete structure used in a test for finding a defect inspection method according to the present invention.
【図２】本発明にかかる欠陥検査方法を見出す試験にお
いて使用したアルミ弾を示した図である。FIG. 2 is a diagram showing an aluminum bullet used in a test for finding a defect inspection method according to the present invention.
【図３】本発明にかかる欠陥検査方法を見出す試験にお
いて採用した弾性波の入力位置及び計測機器の構成を示
した図である。FIG. 3 is a diagram showing an input position of an elastic wave and a configuration of a measuring device adopted in a test for finding a defect inspection method according to the present invention.
【図４】本発明にかかる欠陥検査方法を見出す試験にお
いて得られた応答波形を示した図であって、（ａ）は断
面Ａ、（ｂ）は断面Ｂで得られた応答波形を各々示す。FIG. 4 is a diagram showing response waveforms obtained in a test for finding a defect inspection method according to the present invention, in which (a) shows a response waveform obtained at a section A and (b) shows a response waveform obtained at a section B; .
【図５】本発明にかかる欠陥検査方法を見出す試験にお
いて得られた応答波形を高速フーリエ変換（スペクトル
解析）することにより周波数と振幅との関係を示すスペ
クトルとした図であって、（ａ）は断面Ａ、（ｂ）は断
面Ｂで得られたスペクトルを各々示す。FIG. 5 is a diagram showing a spectrum showing a relationship between frequency and amplitude by subjecting a response waveform obtained in a test for finding a defect inspection method according to the present invention to fast Fourier transform (spectral analysis); Shows a cross section A, and (b) shows a spectrum obtained in the cross section B, respectively.
【図６】本発明にかかる欠陥検査方法を見出す試験にお
いて採用した分析モデルの概要を示した図である。FIG. 6 is a diagram showing an outline of an analysis model adopted in a test for finding a defect inspection method according to the present invention.
【図７】本発明にかかる欠陥検査方法を見出す試験にお
いて得られた応答波形を高速フーリエ変換することによ
りスペクトルとし、該スペクトルが検査断面のどの位置
からの反射の影響を多く含んでいるのかをイメージ化し
た図であって、（ａ）は断面Ａ、（ｂ）は断面Ｂでのイ
メージを各々示す。FIG. 7 is a spectrum obtained by subjecting a response waveform obtained in a test for finding a defect inspection method according to the present invention to fast Fourier transform, and showing from which position of the inspection cross section the spectrum includes the influence of reflection. It is the imaged figure, (a) shows the image in the cross section A, (b) shows the image in the cross section B, respectively.
───────────────────────────────────────────────────── フロントページの続き (58)調査した分野(Int.Cl.7，ＤＢ名) G01N 29/00 - 29/28 G01H 11/00 ＪＩＣＳＴファイル（ＪＯＩＳ)─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. 7 , DB name) G01N 29/00-29/28 G01H 11/00 JISST file (JOIS)
Claims (4)
ンクリート構造物の表面から弾性波を入力し、その時の
コンクリート構造物からの応答波形からコンクリート構
造物中の欠陥の有無を検査するインパクトエコー法を用
いたコンクリート構造物中の欠陥検査方法において、上
記応答波形をスペクトル解析して周波数と振幅との関係
を示すスペクトルとすると共に、上記コンクリート構造
物の検査断面中に複数個の仮想点を想定し、該仮想点に
おいて反射する弾性波の理論周波数を各々の仮想点につ
いて算出し、この理論周波数に対応する上記スペクトル
中の周波数の振幅値を各々の仮想点において求め、この
各々の仮想点における振幅値を比較することによりコン
クリート構造物中の欠陥の有無を検査することを特徴と
する、コンクリート構造物中の欠陥検査方法。1. An impact echo method in which an elastic wave is input from the surface of a concrete structure by dropping or hitting a steel ball, and the presence or absence of defects in the concrete structure is inspected from the response waveform from the concrete structure at that time. In the method of inspecting defects in a concrete structure using, the response waveform is spectrally analyzed to form a spectrum showing the relationship between frequency and amplitude, and a plurality of virtual points are assumed in the inspection cross section of the concrete structure. Then, the theoretical frequency of the elastic wave reflected at the virtual point is calculated for each virtual point, the amplitude value of the frequency in the spectrum corresponding to this theoretical frequency is obtained at each virtual point, at each virtual point Concrete, characterized by inspecting for the presence of defects in concrete structures by comparing amplitude values Defect inspection method in structure.
論周波数を、弾性波の入力点から仮想点を経て応答波形
の検出点に至るまでの距離をＲとした場合、ｆ１＝ＣＰ
／（Ｒ／２）、ｆ２＝ＣＰ／Ｒ、ｆ３＝ＣＰ／２Ｒ、ｆ
４＝ＣＰ／３Ｒ、・・・・ で求められる複数個の周波
数とすると共に、この複数個の理論周波数の各々に対応
する上記スペクトル中の周波数の振幅値の合計を各々の
仮想点において求め、この各々の仮想点における振幅値
の合計を比較することによりコンクリート構造物中の欠
陥の有無を検査することを特徴とする、請求項１記載の
コンクリート構造物中の欠陥検査方法。なお、上記式中
ＣＰは、弾性波のコンクリート構造物中における伝播速
度である。2. When the theoretical frequency of an elastic wave reflected at the virtual point is R, which is the distance from the input point of the elastic wave to the detection point of the response waveform through the virtual point, f 1 = C P
/ (R / 2), f 2 = C P / R, f 3 = C P / 2R, f
4 = C P / 3R, ..., and a plurality of frequencies obtained by the following, and the sum of the amplitude values of the frequencies in the spectrum corresponding to each of the plurality of theoretical frequencies is obtained at each virtual point. The method for inspecting a defect in a concrete structure according to claim 1, wherein the presence or absence of a defect in the concrete structure is inspected by comparing the sum of the amplitude values at the respective virtual points. In the above formula, C P is the propagation velocity of the elastic wave in the concrete structure.
想定する複数個の仮想点を、検査断面を複数個に等分割
した際の各々の分割断面の中心とすることを特徴とす
る、請求項１又は２記載のコンクリート構造物中の欠陥
検査方法。3. A plurality of imaginary points assumed in the inspection cross section of the concrete structure are defined as the center of each divided cross section when the inspection cross section is equally divided into a plurality of sections. The defect inspection method in the concrete structure according to 1 or 2.
を、各々の仮想点における振幅値の大小が視覚的に把握
し得る状態にして行うことを特徴とする、請求項１、２
又は３記載のコンクリート構造物中の欠陥検査方法。4. The amplitude value comparison at each of the virtual points is performed in a state in which the magnitude of the amplitude value at each virtual point can be visually recognized.
Alternatively, the method for inspecting defects in a concrete structure as described in 3 above.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP17489899A JP3523806B2 (en) | 1999-06-22 | 1999-06-22 | Defect inspection method in concrete structure |
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|---|---|---|---|---|
| WO2008123440A1 (en) * | 2007-03-30 | 2008-10-16 | Airec Engineering Corporation | Filling inspecting apparatus, and filling inspecting method |
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| JP6315381B2 (en) * | 2014-09-04 | 2018-04-25 | 株式会社富士ピー・エス | Elastic wave input device and defect search method for concrete structure using the elastic wave input device |
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| CN116893222B (en) * | 2023-08-29 | 2024-04-09 | 铁正检测科技有限公司 | Railway tunnel concrete defect impact echo wave detection method based on artificial intelligence |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2008123440A1 (en) * | 2007-03-30 | 2008-10-16 | Airec Engineering Corporation | Filling inspecting apparatus, and filling inspecting method |
| JP2008249665A (en) * | 2007-03-30 | 2008-10-16 | Metropolitan Expressway Public Corp | Filling degree inspection device and method |
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