JP3009543B2 - Concrete soundness determination method and apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for judging the degree of soundness of concrete, and more particularly to a method and apparatus for judging the presence of cracks and voids inside a concrete structure such as a building from the outside.

[0002]

2. Description of the Related Art Conventionally, a technique disclosed in Japanese Patent Publication No. 4-10987 is known as a technique for externally determining the presence of cracks and voids in a concrete structure such as a building.

In this technique, a concrete surface is hit with a hammer having a spherical head, the hitting sound is directly collected by a microphone, and the collected hitting sound is analyzed to determine the soundness of the concrete.

[0004]

However, in this technique,
Since there are variations in the determination results obtained depending on the condition of the concrete surface (dirt such as mud adhesion, coarse aggregate is present near the surface, etc.), many times (5 to 5)
About 10 or more hits / analysis is required. Therefore, it is extremely troublesome, and has a drawback that when the concrete area to be determined is large, such as a building, it takes an enormous amount of time to make the entire determination.

[0005] Further, since the impact sound is directly collected as air vibration, a super-directional microphone having a sharp directivity must be used so as not to be affected by ambient noise at the time of collection. Unless strictly adjusted to the location of the impact, there is a drawback that accurate sampling of the impact sound and thus accurate determination of the soundness cannot be performed. In particular, there is a drawback that if the determination of the soundness is wrong, there may be a serious accident such as a falling accident due to peeling of the concrete surface, a falling rock, a falling rock, or the like.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a concrete soundness judging method and apparatus capable of easily and accurately obtaining a soundness judgment result of concrete.

[0007]

Means for Solving the Problems The inventors of the present invention have made intensive studies to achieve the above object, and as a result, have accomplished the present invention.

[0008] That is, a concrete soundness determination method according to the present invention is a method for determining the soundness of concrete by hitting a concrete surface and analyzing the hitting sound. It is characterized by being collected and analyzed.

In a preferred embodiment of the method for judging soundness of concrete according to the present invention, a sound insulation member having a sound receiving means such as a sound receiving microphone disposed therein and having an open sound receiving direction is provided for collecting the propagation impact sound. Is carried out close to or close to the concrete surface, and the sound insulating member is a substantially hemispherical hood member.

A concrete soundness judging device according to the present invention is a device for judging concrete soundness by hitting a concrete surface and analyzing the hitting sound. It is characterized by having a sound receiving microphone and an analyzing unit for analyzing the collected propagation impact sound.

In a preferred embodiment of the concrete soundness judging apparatus according to the present invention, the sound receiving microphone is provided in a sound insulating member whose sound receiving direction is open and whose open end can be close to or substantially close to the concrete surface. And that the sound insulating member is a substantially hemispherical hood member.

[0012]

According to the present invention, instead of directly striking the concrete surface and directly collecting the striking sound as air vibration, a structure is provided in which the striking sound transmitted through the concrete itself is sampled and analyzed. Regardless of the condition of the concrete surface, the soundness can be determined by a small number of impacts / analysis, and the soundness of the concrete is easily and accurately obtained because it is not affected by surrounding noise. Can be

[0013]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a schematic side view showing one embodiment of a method and an apparatus for determining the soundness of concrete according to the present invention.

As shown in FIG. 1, a concrete soundness judging device according to the present invention collects a hammer member 2 for striking the surface of concrete 1 and a propagation impact sound transmitted through the concrete 1 itself by the impact of the hammer member 2. The sound receiving microphone 3 is mainly composed of: a sound receiving microphone 3;

The hammer member 2 includes a general hammer used for percussion and the above-mentioned Japanese Patent Publication No. 4-10987.
Or a hammer having a spherical head described in Japanese Patent Application Laid-Open Publication No. HEI 9-205.
In addition, it is preferable to perform the impact mechanically rather than manually so that the impact energy is substantially constant, and it is more preferable to perform the impact with low noise.

As the sound receiving microphone 3, a conventionally known microphone, for example, a microphone such as a sound level meter or the like can be used as long as the hitting by the hammer member 2 can be collected as a propagation hitting sound propagating in the concrete 1 itself. Can be. As for the configuration of the sound receiving microphone 3, if the sound receiving unit 3A is disposed in the member 5 and can receive sound, other components, for example, a meter unit and an amplifier unit are configured separately. You may. When configured separately, the components other than the sound receiving unit 3 </ b> A may be incorporated in the analysis unit 4. In addition, communication between the sound receiving unit 3A and other components is performed by wire / wire.
Regardless of radio.

The sound receiving microphone 3 is provided in a sound insulating member 5 made of a sound insulating material such as rubber or soft synthetic resin so that the sound receiving microphone 3 is not affected by ambient noise or the like.
A is provided, and the sound insulating member 5 has a substantially hemispherical hood in which the sound receiving direction of the sound receiving microphone 3 is open and the open end can be close to or substantially close to the concrete 1 surface. It is a member. Accordingly, the sound insulation member 5 composed of a hood member is brought into close or close contact with the surface of the concrete 1 at its open end, so that the hammer member 2 can collect the impact sound while the surrounding noise and the like are isolated, and the concrete 1 itself can be collected. It can be collected as a transmitted sound. The sound insulating member 5 may have a multi-layered structure or a sound insulating material such as glass wool or rock wool to further enhance the sound insulating effect. It is preferable that the open end of the sound insulating member 5 is close to or close to the surface of the concrete 1 in a pressed state in terms of sound insulation of surrounding noise. However, the sound insulating member 5 is slightly separated, that is, close to the surface. May be. When approaching, concrete 1
The distance from the surface varies depending on various conditions such as ambient noise and the sound insulation performance of the sound insulation member 5, but is preferably within about 20 mm, more preferably within 10 mm, and particularly preferably within 5 mm.
mm. By performing the determination in the proximity state, for example, when the apparatus of the present invention is installed on a traveling platform and continuously determined while moving at many locations, the determination speed is effectively increased.

The analysis section 4 acoustically analyzes the transmitted striking sound collected by the sound receiving microphone 3, and finds an abnormal part from the waveform and frequency spectrum of the striking sound.

In the present specification, the object to be determined is a concrete structure such as a building. However, the present invention is not limited to this, and all of the hitherto performed percussions with a hammer, specifically, For example, the present invention can be applied to inspection of machines, instruments, and products, rock fall, rock fall, etc. in mine pits and tunnel construction sites.

The present invention determines the soundness of the concrete 1 using the apparatus having the above-mentioned configuration. The method for determining the soundness is such that the hammer member 2 hits the surface of the concrete 1 to be measured, Rather than directly collecting the sound as air vibration, the sound-insulating member 5 in which the sound-receiving microphone 3 is disposed is transmitted through the concrete 1 itself with its open end in the sound-receiving direction being in close contact with the surface of the concrete 1. The sound of propagation is sampled and analyzed by the analysis unit 4 to determine the soundness of the concrete 1.
In addition, when determining the actual degree of soundness, it is preferable that the apparatus be installed on a mount that can travel, since the apparatus can be easily moved between the points when a plurality of points are determined.

[0021]

[Experimental example] Hereinafter, an experiment was conducted using a concrete structure as shown in FIG. 2 as an experimental test piece, in which the impact sound was directly sampled as air vibration (comparative example) and in the case where it was sampled as a propagation impact sound (the present invention). Was done.

The test specimen is ordinary concrete containing aggregate cast on a base concrete 1B having a thickness of 20 cm. The thickness of the point A is 20 cm and the point B is 40.
cm, point C = 60 cm. That is, at the point A, 40 c between the specimen concrete and the base concrete
m at the point B.
cm gap portion 6B exists, and at point C, there is no gap portion, that is, a healthy state.

In this experiment, instead of a hammer, steel balls were dropped from a height of 50 cm onto the three points A, B, and C to strike the concrete surface of the specimen, and the sound of the impact was measured using the two methods described above. And the difference in the soundness of the concrete between the points A and B and the point C, that is, the presence or absence of voids is determined.

FIG. 3 shows a method (in accordance with the present invention) of collecting a striking sound as a propagating striking sound propagating in the concrete itself at a point 25 cm from the striking point. In FIG. 3, the sound receiving microphone 3 has its sound receiving portion 3A disposed in a hemispherical rubber hood member which is the sound insulating member 5, and the collected propagation impact sound is analyzed by an analyzing unit (not shown). Configuration.

FIG. 4 shows a method (comparative example) of directly collecting the impact sound as air vibration. In FIG. 4, the sound receiving microphone 3 is configured to directly collect a striking sound due to a steel ball as air vibration, and the collected striking sound is analyzed by an analyzing unit (not shown).

FIG. 5 is a graph showing the waveform and frequency spectrum of a striking sound obtained by sampling the test piece shown in FIG. 2 by the judgment method and apparatus of the present invention. FIG. 6 shows a conventional method and apparatus using the test piece shown in FIG. FIG. 4 is a graph showing a waveform and a frequency spectrum of a striking sound collected by the method.

In the method of collecting the propagation impact sound shown in FIG. 3 (the present invention), as shown in the graph of FIG. 5, the low frequency sound is clearly dominant at the point A, and the point B is inferior to the point A. However, it can be seen that there is a clear difference compared to the point C.

On the other hand, in the method of directly collecting the impact sound shown in FIG. 4 (comparative example), as shown in the graph of FIG.
It can be seen that there is a difference from point C at point, but B
It can be seen that the difference from point C is unclear at point.

In collecting the impact sound, the method shown in FIG. 3 has little variation and can be judged by a small number of impacts of about 1 to 3 times at each point, but is shown in FIG. In the method, the variation between hits is large.
A large number of hits, such as 10 or more hits, must be taken to determine the average value, which is extremely complicated.

Further, in the method shown in FIG. 3, there is almost no influence due to the difference in the local properties of the hitting point, but in the method shown in FIG. 4, mud or the like adheres to the hitting point or the surface of the hitting point It was found that the amplitude of the impact sound was large when there was aggregate in the vicinity, and the effect of local differences in properties was significant.

[0031]

According to the present invention, instead of directly striking the concrete surface and directly collecting the striking sound as air vibration, the structure has a structure in which the striking sound transmitted through the concrete itself is sampled and analyzed. Regardless of the condition of the concrete surface, the soundness can be determined by a small number of impacts / analysis, and it is not affected by the surrounding noise, etc. Can be easily obtained. Therefore, even if the concrete area to be determined is large like a building or the like, there is an effect that the entire determination can be obtained in a shorter time than before. In addition, since an accurate determination result can be obtained, there is an effect that an accident or the like due to erroneous soundness determination can be prevented beforehand.

[Brief description of the drawings]

FIG. 1 is a schematic side view showing one embodiment of a method and an apparatus for determining the soundness of concrete according to the present invention.

FIG. 2 is a schematic sectional view of a concrete structure specimen used in the experiment.

FIG. 3 is a schematic side view partially cut away showing an experimental method.

FIG. 4 is a schematic side view showing an experimental method.

FIG. 5 is a graph showing a waveform and a frequency spectrum of an impact sound obtained by sampling the test piece shown in FIG. 2 by the determination method and apparatus of the present invention.

6 is a graph showing a waveform and a frequency spectrum of an impact sound obtained by sampling the test piece shown in FIG. 2 by a conventional method and apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Concrete 2 Hammer member 3 Sound receiving microphone 3A Sound receiving part 4 Analysis part 5 Sound insulation member

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-55-122147 (JP, A) JP-A-57-175952 (JP, A) Fully open 1988-73668 (JP, U) Really open 1987 32362 (JP, U)

Claims (2)

(57) [Claims] 1. A method for judging the soundness of concrete by analyzing the impact sound by hitting a concrete surface, wherein sound receiving means is arranged at a position distant from a hit point. The sound receiving means is a blow sound (vibration) propagated in concrete
And a sound-insulating member that has a sound receiving direction that is open and has a substantially hemispherical hood member, and that propagates through the concrete itself. A soundness determination method for a concrete structure, wherein the propagation impact sound is collected as air vibration by the sound receiving means in which the sound insulation member is brought into close or close contact with a concrete surface, and analyzed by the analysis unit. 2. An apparatus for judging the soundness of concrete by hitting a concrete surface and analyzing the hitting sound, comprising: a hitting means for hitting the concrete; and a sound receiving means arranged at a position distant from the hitting means. Means, and an analyzing unit for analyzing the collected propagation impact sound, wherein the sound receiving means includes a microphone for sampling the impact sound (vibration) propagated in the concrete as air vibration, and the microphone is internally provided. And a sound insulation member having a substantially hemispherical hood member in which the sound receiving direction is released.