JPH0821824A - Probing method for defective filling - Google Patents

Abstract

PURPOSE:To correctly detect a defective fill portion regardless of the kind of a plate by bringing an acoustic wave transmitting probe and a receiving probe into contact with the surface of the plate, repeatedly transmitting acoustic waves containing wide- band frequency constituents to a filler from the surface of the plate, receiving the reflected waves, converting them into an electric signal, and processing the CONSTITUTION:An acoustic wave transmitting probe 11 and an acoustic wave receiving probe 12 are brought into contact with a plate 20, radio wave pulses from an oscillator 13 are converted into low-frequency acoustic waves via the transmitting probe 11, and the acoustic waves are repeatedly transmitted to a filler 30. The transmitted frequency band contains wide-band frequency constituents ranging from 10Hz to 100kHz, for example, and resonance occurs on the plate 20, the filler 30, and a defective fill portion 31 having different resonance frequencies. The receiving probe 12 converts the received oscillation waves into an electric signal, and the signal is fed to an FET analyzer 14 via the oscillator 13 for a Fourier analysis. Since the output level of the defective fill portion 31 reaches 5-10 times that of a satisfactory fill portion, the defective fill portion 31 can be detected regardless of the kind and thickness of the plate 20.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for investigating a filling defect filled on the back surface of a plate body from the surface of the plate body by means of sound waves for a filling failure.

[0002]

2. Description of the Related Art In the construction of concrete structures, a method is generally used in which a wooden form is assembled at a predetermined position and concrete is placed in the form to form the structure. If there is a defective portion such as a void in the concrete during the concrete pouring, a structure having a predetermined strength cannot be constructed. For this reason, it is necessary to search for such defective parts after concrete is poured.
Conventionally, the exploration method has been to listen to the sound generated by hitting the outside of the formwork on which the concrete has been cast, that is, the surface side, and search for the defective part of the concrete filling by the frequency of the sound.

[0003]

[Problems to be Solved by the Present Invention] The above-described conventional search method has the following problems.

<B> Due to technological development in structures and construction methods thereof, a fixed form made of steel plate having a thickness of about 60 mm, concrete having a thickness of about 30 mm or other various building materials is used for the form. There are cases.
In such a case, even if the mold is struck, a loud sound that can be searched is not generated, and a difference in sound that can identify the presence or absence of a defective filling portion such as a void on the back side cannot be obtained. Therefore, it is not possible to confirm the existence of the defective filling portion in those molds.

<B> If the range of the defective portion of the concrete filling is narrow, no difference in sound can be obtained to identify the presence or absence of the defective filling portion, and the existence of the defective filling portion cannot be known.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object thereof is to provide a method for searching for a filling failure that can reliably search a filling failure portion regardless of the type of plate body. Is to provide.

[0007]

That is, according to the present invention, in a method for investigating a filling failure of a filling material existing on the back surface side of a plate body, a method for transmitting a sound wave and a probe for receiving a sound wave are provided. The wave receiving probe is brought into contact with the surface of the plate body, and the wave transmitting probe repeatedly transmits a sound wave having a broadband frequency component from the surface side of the plate body toward the filling material, and the reflected wave The wave is received by the wave receiving probe and converted into an electric signal, and the received signal is F
Input to FT analyzer, perform Fourier analysis, and FFT
It is a method for detecting a filling failure by measuring the level of the frequency spectrum output from the analyzer and determining the filling failure.

The present invention also provides, in the above-described method for investigating defective filling, the plate body is a mold for constructing a concrete structure, and the filler is a grout material filled in the mold. It is a method of detecting a filling failure, which is characterized by the fact that

[0009]

Embodiment 1 An embodiment will be described below with reference to the drawings. The term "sound wave" in the following description means a sound wave including a low frequency sound wave and a high frequency sound wave.

<B> Searching Device First, the searching device 10 used in the searching method will be described. As shown in FIG. 1, the exploration device 10 includes a transmitting probe 11 that transmits a sound wave, a receiving probe 12 that receives the transmitted reflected wave, an oscillator 13, and an FFT analyzer 14. ing. Hereinafter, each member will be described in detail.

(1) Wave Transmitting Probe The wave transmitting probe 11 is a piezoelectric element that converts an electric signal sent from the oscillator 13 into a sound wave, and is connected to the oscillation output end of the oscillator 13. The wave transmission probe 11 has a wide wave transmission band. That is, a device that generates a broadband sound wave by inputting an electric pulse such as an impulse wave or a rectangular wave is used. The term "wideband sound wave" as used herein refers to a sound wave group having a certain frequency band as well as a specific frequency. For example, the frequency band of the sound wave transmitted by the input of an electric pulse is several tens Hz to 100 kHz. A wide range can be adopted. The transmission frequency band of the transmission probe 11 is not limited to several tens to 100 kHz, and different frequency bands suitable for the search target may be used.

(2) Receiving probe The receiving probe 12 is a member for converting the received sound wave into an electric signal. The output end of the receiving probe 12 is directly connected to an FFT analyzer 14 described later to convert the converted signal to F
Although it may be input to the FT analyzer 14, it is connected to the amplifier of the oscillator 13 as shown in FIG.
Connect to the analyzer 14. The wave receiving probe 12 also has a wide wave receiving band similar to that of the wave transmitting probe 11.

(3) Oscillator The oscillator 13 is a device that oscillates an electric pulse signal to be input to the wave transmitting probe 11, and has an amplifier 131 (not shown) for a wave receiving signal as described above. Is preferably used. The amplifier 131 may of course be separate from the oscillator 13. Further, as the oscillator 13, one that can change the oscillation frequency to several tens Hz to 10 kHz is used.

(4) FFT Analyzer The FFT analyzer 14 is a known device for performing Fourier analysis (spectral analysis) on the amplified received signal. That is, the FFT analyzer 14 is a device that displays the received signal as a frequency spectrum on the display panel 141.

<B> Object to be searched The object to be searched is a structure having the filler 30 on the back surface of the plate 20. As an example of the exploration target, there is a concrete structure under construction in which concrete, mortar or other grout material which is a fluid for construction is filled in a formwork when the concrete structure is constructed. Specifically, a wall body 43 such as a house formed by filling a grout material 42 between fixed molds 41 arranged in parallel as shown in FIG.
A column 52 such as a building formed by filling a grout material 42 into a fixed form 51 having a hollow prismatic shape as shown in FIG.
Two pillars 62 for supporting the road 61 as shown in FIG. 5, which are diagonally arranged and intersect with each other in an X shape and are formed by filling the grout material 42 in the form 63, as shown in FIG. There is a column 63 whose lower part has a skirt-like shape and which is formed by filling the grout material 42 in the mold 63. The locations where the filling failure portion 31 is formed in these structures are the molds 41, 51, 63 and the grout material 42.
In many cases, in the columns 62 and 64, the defective filling portion 31 is formed particularly in the lower inclined portion.

In those cases, the grout material in a fluidized state that is not yet solidified corresponds to the filler 30, but the filler 30 may be a grout material during curing or after curing. Further, it is applicable regardless of whether the formwork is made of wood, steel, concrete, aluminum, resin, or the like. Further, the defective filling portion 31 to be searched is a void formed between the plate body 20 and the filling material 30, a lump such as coarse aggregate or bubbles. The object to be searched is not limited to the concrete structure, and can be applied to other structures as long as the structure has the filler 30 on the back surface of the plate 20.

<C> Exploration Principle The exploration principle will be described. As shown in FIG. 1, sound waves are transmitted at a low repetition frequency from the surface side of the plate body 30 on the back side of which the filler 30 is present. At that time, since the sound wave that is transmitted has a different resonance frequency depending on the range of the filling failure portion 31, the thickness of the plate body 30, and the like, instead of transmitting a sound wave of a specific frequency, a wide band sound wave is transmitted. It is essential to receive and measure the frequency spectrum. Also, it is necessary to repeatedly transmit the received signal for Fourier analysis.

When the defective filling portion 31 does not exist, as shown in FIG.
As shown in FIG. 4, the sound wave transmitted from the surface side of the plate body 20 by the wave transmitting probe 11 travels in the filling material 30 and is hardly reflected to the wave receiving probe 12, and is transmitted to the FFT analyzer 14. Shows almost no frequency spectrum. On the other hand, as shown in FIG. 1, if there is a filling failure portion 31 such as a gap between the filling material 30 and the plate body 20, the sound wave transmitted by the transmitting probe 11 from the surface side of the plate body 20 is filled. It does not proceed into the material 30, is reflected by the back surface of the plate body 20, and is detected by the wave receiving probe 12 as a reflected wave or a vibration wave. And the receiving probe 1
The signal obtained in 2 is Fourier analyzed by the FFT analyzer 14 and displayed as a frequency spectrum. By measuring the output level of this frequency spectrum, the presence / absence of the defective filling portion 31 can be easily searched.

<D> Search method First, the transmitting probe 11 is connected to the oscillation output end of the oscillator 13, the receiving probe 12 is connected to the amplifier input end of the oscillator 13, and the amplifier output end and the FFT analyzer are connected. Connect the input end of 14 and set the exploration measuring equipment. The power of the oscillator 13 and the FFT analyzer 14 is turned on, and a pulse is input from the oscillator 13 to the wave transmission probe 11 at a predetermined repetition frequency so that a wide band sound wave can be transmitted from the wave transmission probe 11. The repetition frequency is, for example, 0.5 to 2 kHz.
Alternatively, another optimum frequency may be selected which is easy to search depending on the difference of the object to be searched. Further, the output level of the FFT analyzer 14 is set to a predetermined level at which the difference in the frequency spectrum that appears depending on the presence or absence of the filling failure portion 31 at the search position becomes remarkable.

Then, as shown in FIG. 1, the wave transmitting probe 11 and the wave receiving probe 12 are brought into contact with the surface of the plate body 20 which is the object to be searched, and a wide band sound wave is emitted from the wave transmitting probe 11. Waves are repeatedly transmitted toward the filling material 30 on the back surface side of the plate body 20. Plate 20
When the filling failure portion 31 does not exist on the back surface side, the transmitted sound wave propagates into the filling material 30 and is not largely reflected on the back surface of the plate body 20, as shown in FIG. Therefore, almost no sound wave is detected from the receiving probe 12, and no frequency spectrum appears on the display panel 141 of the FFT analyzer 14.

On the other hand, as shown in FIG. 1, when the filling failure portion 31 exists on the back surface side of the plate body 20, the transmitted sound wave is
Almost no progress to the inside of the filling material 30 and reflection on the back surface of the plate body 20. As a result, the reflected wave reciprocates between the front and back surfaces of the plate body 20, and the plate body 20 of the filling failure portion 31 vibrates.
The main vibration is bending vibration in the filling failure portion 31 of the plate body 20. This flexural vibration may not only vibrate at a predetermined cycle, but may also be a complex vibration containing harmonics. Further, in addition to the flexural vibration, there may be vertical vibration that reciprocates in the thickness direction of the plate body 20. Then, those vibrations are detected by the wave receiving probe 12. At that time, the frequency of the sound wave that vibrates varies depending on the conditions such as the thickness of the plate body 20 and its material and the range of the filling failure portion 31, but since the sound wave to be transmitted contains a wide frequency component, Even if the plate body 20 vibrates only by the wave of the frequency component that meets the conditions, it can be reliably detected. The signal detected by the receiving probe 12 is amplified by the amplifier of the oscillator 13 and then input to the FFT analyzer 14 and displayed as a frequency spectrum on the display panel 141.

The frequency spectrum showing the existence of the defective filling portion 31 is various, such as when it appears at a low frequency of about several hundreds of Hz, when it appears at a high frequency of about 50 kHz, or when it appears entirely over a wide frequency range. However, the output level of the frequency spectrum at the position where the defective filling portion 31 exists has a value that is 5 to 10 times higher than that at the position where the defective filling portion 31 does not exist. Therefore, by measuring the output level of the frequency spectrum, the existence of the defective filling portion 31 can be easily confirmed.

The display panel 1 of the FFT analyzer 14
While looking at 41, the transmission probe 11 and the reception probe 12
By sequentially contacting the plate body 20 with the surface of the plate body 20 and moving the plate body 20, it is possible to quickly detect the existence of the defective filling portion 31 in a wide range.

[0024]

Second Embodiment When the object to be searched is an important structure, the search result of the defective filling portion 31 may be verified. As a verification method, for example, a screw hole penetrating the fixed mold is provided, and the fixed mold is arranged with a screw screwed in the screw hole, and the grout material is filled inside. And
The presence or absence of the defective filling portion 31 is searched in the same manner as in the first embodiment, and the search result is obtained. Next, the screw is removed from the fixed mold and the presence or absence of defective filling is confirmed by a visual inspection. If the result of the visual inspection and the result of the exploration are consistent, the exploration of the filling failure is continued only by the exploration, and if the result of the visual acuity inspection and the result of the exploration do not match, the repetition frequency for transmitting a sound wave is changed, Further, the output setting of the output level of the frequency spectrum in the FFT analyzer 14 is changed and the search is performed again. If the exploration is performed in this way, the reliability of the exploration can be improved.

[0025]

[Third Embodiment] The object to be searched in the first or second embodiment may be one in which a plate is attached to the surface of a structure through a filler. In that case, it is possible to search for the defective filling portion 31 of the filling material. Specific examples of the object of exploration include structures 67 such as viaducts in which a slab 65 is supported by girders 66 through grout materials 42 as shown in FIG. 7, and a large motor 71 as concrete in FIG. 8. There is a facility 73 placed on the structure 72 via the grout material 42. In the structure 67, the upper surface of the girder 66 has a plate shape, and a sound wave is transmitted from the upper surface toward the grout material 42, and by the exploration method of the first embodiment, a defective filling portion of the grout material 42 is detected. The presence or absence can be searched. In the equipment 73, the lower part of the motor 71 is in the form of a plate that comes into contact with the concrete structure 72 through the grout material 42, and a sound wave is transmitted from the lower part toward the grout material 42 to search for the first embodiment. According to the method, it is possible to detect the presence or absence of a defective filling portion of the grout material 42.

[0026]

Fourth Embodiment The object to be searched in the first to third embodiments may be a structure in which a hollow pipe 82 is embedded in concrete 81. In that case, concrete 8 from the inner peripheral side of the hollow pipe 82
According to the exploration method of the first embodiment by transmitting sound waves toward No. 1, it is possible to investigate the presence or absence of a gap between the outer peripheral surface of the hollow tube 82 and the concrete 81.

[0027]

Since the present invention is as described above, the following effects can be obtained.

<B> By transmitting a wide-band sound wave from the surface of the plate to search for a filling failure, it goes without saying that a wooden mold can be searched for a filling failure. It is possible to search for what was there. That is, it is possible to reliably search for a filling failure of the filling material that is filled on the back surface side of a fixed form frame made of a steel plate having a thickness of about 60 mm, concrete having a thickness of about 30 mm, or other various building materials.

<B> Since the transmitted sound wave has a wide band, any frequency component thereof is reflected to generate vibration in the plate body. Therefore, regardless of whether the range of the defective filling portion is wide or narrow, the defective filling portion can be reliably searched.

[Brief description of drawings]

FIG. 1 Explanatory diagram of exploration method

[Fig. 2] Explanatory diagram of exploration method

[Fig. 3] Explanatory drawing of exploration target

[Fig. 4] Explanatory diagram of exploration target

[Fig. 5] Explanatory diagram of exploration target

[Fig. 6] Explanatory diagram of exploration target

FIG. 7 is an explanatory diagram of the third embodiment.

FIG. 8 is an explanatory diagram of Example 3.

FIG. 9 is an explanatory diagram of the fourth embodiment.

Claims (2)

[Claims] 1. A method for investigating a filling failure of a filling material existing on the back surface side of a plate body, wherein a wave transmission probe for sound wave transmission and a wave reception probe for sound wave reception are provided on the plate body. It abuts the surface, and the transmitting probe repeatedly transmits a sound wave having a broadband frequency component from the surface side of the plate toward the filling material, and the reflected wave is received by the receiving probe. Then, the received signal is input to the FFT analyzer, Fourier analysis is performed, and the level of the frequency spectrum output from the FFT analyzer is measured to determine the filling failure. . 2. The method for exploring filling failure according to claim 1, wherein the plate body is a mold for constructing a concrete structure, and the filler is a grout material filled in the mold. A method for detecting poor filling, which is characterized in that