JP2001021336A - Method and device for measuring degradation of concrete structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately and nondestructively measure and detect the degree of degradation of a concrete structure at a deep portion by analyzing the deviation between the resonance frequency spectra from a defectless section and other sections. SOLUTION: The reference resonance frequency spectrum of the defectless section of a concrete structure 10 to be measured is prepared in advance by measuring the resonance frequency of the section by applying vibrations to the section. Then the resonance frequency spectrum of another measured section is prepared by measuring the resonance frequency of the section by applying vibrations to the section. Then the degree of degradation of the internal portion of the concrete structure 10 is discriminated by analyzing the deviation between both prepared resonance frequency spectra by superposing the spectra upon another. An impulse method in which a prescribed portion is hit with an impact hammer 11, etc., is used as the vibration applying means. The vibration applying force of the hammer 11 and the vibration of the structure 10 are respectively detected by means of a force detecting pickup 16 and an acceleration pickup 16 and the signals of the pickups 12 and 16 are inputted to a high-speed Fourier transformation analyzer 15.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention belongs to the technical field of measuring the degree of deterioration of the internal structure of a concrete structure without destroying the concrete structure.

[0002]

2. Description of the Related Art Deterioration of reinforced concrete structures is caused by corrosion of reinforcing steel, alkali-aggregate reaction, and frost damage.
Softening of cement, that is, reduction of pressure resistance due to destruction of the internal structure of the concrete, cracking, that is, cracking, concrete cracking due to corrosion and rusting of the reinforcing steel, separation of the reinforcing steel from the concrete, etc. Before doing so, it is desirable to know the extent of its degradation. Conventionally, in order to measure the degree of deterioration of the internal structure of a concrete structure, a sample is taken from a predetermined portion of the concrete structure, a compression test is performed, the composition is further made into powder, and the composition is analyzed to determine the degree of lime alteration. Deterioration measurement method to detect,
It is generally known as a means for surely knowing the degree of deterioration, and, as disclosed in JP-A-8-29413, drilling a plurality of thin inspection holes in a concrete structure,
Methods of inserting a fiberscope or the like to inspect the progress of cracks and the like are known, but in any case, it is necessary to collect a sample or drill an inspection hole. Therefore, a method of nondestructively detecting the degree of deterioration of the internal structure of a concrete structure is required. Conventionally, the approximate degree of deterioration can be known visually from the appearance of a concrete structure by its color, etc. Various methods of detecting the degree of deterioration of concrete structures have been proposed in order to make it difficult to obtain an evaluation and to obtain an objective evaluation in a non-destructive manner.

[0003] For example, a method is known in which a displacement gauge or a strain gauge is installed on the surface of a concrete structure, and the degree of deterioration is determined by measuring the deformation caused by corrosion of the reinforcing bar over time. In addition, as proposed in Japanese Patent Application Laid-Open No. 8-15126, each surface of a concrete structure is scanned with an ultrasonic wave, and the obtained distance measurement value is compared with a preset reference value of the entire building. And the degree of deterioration is detected. Further, as proposed in Japanese Patent Application Laid-Open No. H11-30510, unevenness on the surface of a concrete structure is measured by scanning a distance sensor on a straight line, and a deterioration state is detected from the measured unevenness. Furthermore, as disclosed in JP-A-5-108796, the surface temperature distribution of the concrete structure is detected by an infrared sensor, and compared with the temperature distribution of the concrete structure in a healthy state, a unique temperature distribution is obtained. When it was detected, it was judged and evaluated as a deteriorated part.

[0004] As a method of measuring deterioration of a concrete structure, which has been relatively well-established, a method of measuring a natural potential and analyzing a degree of deterioration is known.

[0005]

However, in the above-mentioned conventional method for inspecting and measuring the degree of nondestructive deterioration of a concrete structure, for example, in a method for measuring a change in shape with time using a strain gauge, etc. Deterioration at a shallow site can be detected relatively accurately, but there is a problem that the degree of deterioration of an internal tissue, particularly at a deep site, cannot always be measured and detected accurately. Also, in the method of measuring the surface temperature distribution by an infrared sensor, deterioration at a shallow portion from the surface can be detected relatively accurately, but the degree of deterioration of internal tissue, particularly at a deep portion, cannot always be measured and detected accurately. In addition to the point, there was a problem that the temperature control was difficult. Further, the method of measuring the self-potential is most suitable for mainly detecting the degree of deterioration of a reinforcing bar, but is not suitable for detecting deterioration or cracks of concrete itself.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a concrete structure capable of non-destructively measuring and detecting the degree of deterioration at a deep portion inside a concrete structure. An object of the present invention is to provide a method for measuring deterioration of an object and a measuring device therefor.

[0007]

In order to solve the above-mentioned problems, according to the first aspect of the present invention, in a concrete structure having a portion having substantially the same thickness, a sound portion of a concrete structure to be measured in advance is used. To measure the resonance frequency of the sound part to create a reference resonance frequency spectrum of the sound part, and to excite other measurement parts to measure the resonance frequency of the measurement part to create the resonance frequency spectrum of the measurement part. This is a method for measuring the deterioration of a reinforced concrete structure in which the created two resonance frequency spectra are superimposed and the degree of the deterioration of the internal structure is determined by analyzing the degree of deviation between the two resonance frequency spectra. Then, analyze the degree of complexity that is more complicated than the sound part spectrum, or
By analyzing the degree of dulling of the peak of the spectrum, the degree of softening, cracking, and detachment of the reinforcing steel from the concrete at the measuring point is measured. In order to solve the above-mentioned problem, the invention according to claim 2 is a method of vibrating a sound portion of a concrete structure to be measured in advance in a sound structure of a concrete structure having a portion having substantially the same thickness. Detect the reference resonance frequency of the fundamental mode of vibration, calculate the value of the reference phase velocity from the reference resonance frequency, and excite other measurement units to peak the resonance frequency of the vibration measurement unit near the reference frequency. , A phase velocity value of the vibration is calculated from the resonance frequency of the measuring part at the peak, the two phase velocity values are compared, and the value of the difference is analyzed to determine the degree of deterioration of the internal structure of the reinforced concrete structure. This is a method for measuring the deterioration of the device. Then, the degree of deterioration of the internal structure of the reinforced concrete structure is quantitatively determined based on the value of the phase velocity of the vibration. In order to solve the above-mentioned problem, the invention according to claim 3 provides a concrete structure having a portion having substantially the same thickness, and vibrates a sound part of the concrete structure to be measured in advance to reduce the resonance frequency. Measure and create a reference resonance frequency spectrum of the healthy part, and also vibrate the other measurement parts to measure the resonance frequency of the measurement part, create the measurement part resonance frequency spectrum, and create the two resonance frequency spectra Are superimposed on each other, and the degree of deviation between the two resonance frequency spectra is analyzed to determine the degree of deterioration of the internal structure. To solve the above issues,
According to a third aspect of the present invention, in a concrete structure having a portion having substantially the same thickness, a sound portion of a concrete structure to be measured is vibrated in advance to set a reference resonance frequency of a fundamental mode of vibration in the sound portion. Detecting and calculating the value of the reference phase velocity from the reference resonance frequency, and vibrating another measurement unit to detect a peak of the resonance frequency of the vibration measurement unit near the reference frequency, and measuring at the peak. This is a deterioration measurement device for a reinforced concrete structure that calculates a phase velocity value of vibration from a partial resonance frequency, compares the two phase velocity values, and analyzes the difference value to determine the degree of deterioration of the internal structure.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Here, a method and a device for measuring the degree of deterioration of the internal structure of a concrete structure suitable for the present invention will be described. First, the method for measuring the degree of deterioration of the internal structure of a concrete structure according to the present invention will be described. And the principle of the measuring device will be described.
The present inventors have generally noted that one of physical quantities representing the strength of an object is a Young's modulus E. The larger the Young's modulus E, the higher the compressive strength of the object, and in a non-destructive state,
Measuring the compressive strength inside a reinforced concrete structure has been studied extensively. As a method of measuring the Young's modulus E, there is a method of measuring the Young's modulus E of an object by measuring the resonance frequency of the object. This measuring method uses a finite-sized elastic material such as a concrete structure. The body has a number of natural vibration modes, and these mode frequencies are numerical values determined by the material, shape, and dimensions of the concrete structure. When a concrete structure that is an elastic body is hit, a natural vibration mode of the concrete structure is excited by a finite size, for example, a thickness or a dimension, and vibrates at the natural frequency (resonance phenomenon). Is excited depends on the hitting position and how to hit. For example, there are many natural vibration modes of a floor slab concrete structure of a bridge, but as described above, the mode to be excited generally differs depending on the hitting position. The present inventors have found that in a floor slab concrete structure, when the thickness of the floor slab concrete is substantially constant, there are several modes that are excited regardless of the hitting position.

These are vibration modes of transverse and longitudinal waves in the thickness direction of the floorboard, and the frequencies of the fundamental modes of these vibrations are given by the following equations (1) to (4). (1) Shear wave resonance frequency fs = vs / 2h (2) Shear wave propagation velocity vs = √1 / 2 (1 + σ) E / ρ (3) Longitudinal wave resonance frequency fp = vp / 2h (4) Longitudinal wave propagation velocity vp = √ (1−σ) / (1 + σ) (1-2σ) · E / ρ where h: thickness of floorboard, σ: Poisson's ratio, ρ: density,
It is. However, in practice, the above-mentioned transverse wave and longitudinal wave are complex waves and cannot be strictly distinguished, so strictly speaking, in the present invention and the examples, the transverse wave is “transverse wave” and the longitudinal wave is “longitudinal wave”. However, in this specification, they are simply defined as “lateral wave” and “longitudinal wave”.

As described above, the deterioration of the reinforced concrete structure is caused by the softening of cement, cracking,
Although the phenomenon such as separation of the reinforcing bars occurs, the present inventors have found that the relationship between the deterioration of the reinforced concrete structure and the above-mentioned resonance frequency is related to h: the thickness of the floorboard, σ: Poisson's ratio, and ρ: density. , For concrete structures having the same thickness,
With respect to the phenomenon of cement softening, it has been found that any of the above resonance frequencies shifts to a lower one and the peak of the spectrum becomes dull. It has also been found that the spectrum becomes complicated and the peak of the resonance frequency is not clear for phenomena such as cracks and loosening of reinforcing bars.

In this embodiment, based on the above findings, FIG.
The measurement system shown in Fig. 1 was assembled and used, and the system will be described below with reference to the drawings. The reinforced concrete structure to be measured to confirm the above principle is
As shown in FIG. 2, this is a sound floor model of reinforced concrete having a thickness h = 0.23 m and a floor plate of 1 m square. First, as a vibrating means for applying vibration to the reinforced concrete structure 10 (in FIG. 1, a reinforced concrete floor plate model, or a reinforced concrete to be measured), an impulse method in which an impact hammer 11 strikes a predetermined portion,
Or vibration is given by a vibrator that generates sinusoidal vibration,
A sweep method for sweeping the frequency can be applied. In this embodiment, the impact hammer 11 is used. This hammer 1
1 is provided with exciting force detecting means for detecting an exciting force by a force detecting pickup 12 and outputting an electric signal. This electric signal is amplified as a vibration detecting signal 13 by a preamplifier 14 and Analyzer 15 (fast fourier transfor
m) of the first channel 15 of the FFT analyzer section (not shown)
Entered in 1. As a vibration detecting means for detecting the vibration of the reinforced concrete structure 10, an acceleration pickup 16 is attached to the upper end surface of the reinforced concrete structure 10. This mounting means is firmly mounted via an adhesive such as an instantaneous adhesive in order to increase the accuracy of vibration detection. The acceleration pickup 16 is a piezoelectric acceleration pickup capable of detecting a vibration component, and converts the vibration in each direction into a vibration detection signal 17 of an electric signal and outputs the signal. This vibration detection signal 17 is amplified by the charge amplifier 18 and
The signal is input to a second channel 152 of an FFT analyzer (not shown) of the T analyzer 15.

The FFT analyzer unit converts the input excitation detection signal 13 and vibration detection signal 17 into A / D signals, respectively.
After that, a Fourier transform is performed by an arithmetic processing by a computer, and the vibration waveform is analyzed into a frequency spectrum. By the way, in the case of the impulse method in which the reinforced concrete structure 10 is hit with the impact hammer 11,
Since the frequency spectrum of the excitation force is not flat, the standard is determined by taking the ratio between the frequency spectrum of the excitation detection signal 13 obtained by detecting the excitation force of the impact hammer 11 and the frequency spectrum of the vibration detection signal 17. And measure it as a frequency response. A frequency response function (frequency spectrum) obtained by analyzing the frequency of the vibration detection signal 17 thus measured is displayed on the display screen. If necessary, the output of the frequency spectrum may be input to the peak reading device 19, and the necessary data may be extracted and printed out from the printer 21 via the personal computer 20, and the analyzed frequency spectrum data may be output. The data is recorded on a recording medium such as a floppy disk (FD). The shape calculation device of the FTT analyzer 15 is configured using a microcomputer including an input device, a calculation processing device, a storage device, an output device, and the like. The storage device stores in advance the items necessary for the shape measurement calculation processing, such as the resonance condition formulas, related calculation formulas, and calculation processing programs set based on the above-described principle. A frequency spectrum is calculated from the output from the pickup 16, that is, a graph of the frequency response function is output via an output device such as the display of the FTT analyzer 15 or the printer 21.

The reinforced concrete structure 10 to be measured here is a sound slab model 101 of reinforced concrete with a thickness of h = 0.23 m and a 1 m square slab shown in FIG.
FIG. 3 is a graph showing the result of measuring the floor panel model 101 using the above-described measurement system. And, as described above, in the floor slab concrete structure, there are several modes that are excited regardless of the hitting position, and the fundamental mode frequency of the transverse and longitudinal wave vibration modes in the thickness direction of the floor slab is as described above ( It is given by 1) to (4). In the graph of FIG. 3, the horizontal axis represents the resonance frequency and the vertical axis represents the vibration intensity function.
As described above, the vibration intensity function is normalized by taking the ratio between the frequency spectrum of the vibration detection signal 13 obtained by detecting the vibration force of the impact hammer 11 and the frequency spectrum of the vibration detection signal 17, and FTT measured as number response
It is a dimensionless value that is a value standardized by the analyzer 15. In this case, it suffices if the peak frequency of the frequency response can be detected,
In the present invention, a value of the vibration intensity itself is not particularly required. The measurement results show that the floor panel model 101 is a square prism having a finite length of 1 m square and a thickness of h: 0.23 m. Therefore, many frequency peaks appear in the graph of FIG. The frequencies of the fundamental modes of the transverse and longitudinal vibration modes of the obtained concrete structure also appear as relatively sharp peaks with the following values. As will be described later, in a sound part such as a wall having a wide area with a thickness h: 0.23 m serving as an actual measurement part, the number of peaks is relatively small with a relatively simple spectrum.

(1) Resonance frequency of shear wave: fs = 5.3 kHz Propagation velocity of shear wave with respect to the above frequency: vs = 2.4 km / s (2) Resonance frequency of longitudinal wave: fp = 8.3 kHz Propagation speed of longitudinal wave with respect to: vp = 3.8km / s

Based on the above fact, the spectrum of the resonance vibration of the actual reinforced concrete structure was measured. In fact, we measured the part of the concrete wall of the floorboard where the thickness of the Tohoku Expressway Toyosawa River Bridge was about 0.23m. And the thickness
h: In the sound part of a concrete structure with a floor panel of 0.23 m, the fundamental mode frequency of transverse and longitudinal wave modes is fs = 5.3
kHz, fp = 8.3kHz
Analyze the frequency spectrum of the resonance vibration in the vicinity, calculate the phase velocity value from the peak frequency value, and further take a sample of the concrete structure part, and check the actual state of the cracked state and free lime state Was analyzed and the two were compared.

[Embodiment 1] Next, a first embodiment of a concrete deterioration measuring method and a measuring apparatus by resonance frequency measurement of the present invention will be described. As a result of vibration of a concrete floor plate with a thickness h: 0.23m of the object to be measured and measurement and analysis of the resonance frequency of the concrete structure, the concrete structure in the actual healthy part showed a shear wave around 5kHz. It was found that the peak of the resonance frequency appeared clearly, but the peak of the longitudinal resonance frequency, which should appear around 8 kHz, was unclear. It is considered that disturbance noise is apt to be mixed in at a high frequency of 8 kHz, and at present, only a low-sensitivity measuring instrument can be obtained. Also,
It was found that the spectrum of the cracked portion became complicated and that the resonance frequency was not clear. As a matter of course, if the peak of the resonance frequency can be clearly determined depending on the target concrete structure or the measuring instrument even at the high frequency of 8 kHz, the measurement may be performed using the high frequency longitudinal vibration of 8 kHz.

Next, specific results obtained by measuring an actual concrete structure will be described with reference to FIGS. FIG.
The spectrum of the concrete structure having the spectrum shown in FIG. 5 to FIG. 5 is relatively simple, the peak of the resonance frequency of the shear wave clearly appears around 5 kHz, and the vibration intensity function represented by the vertical axis is large. The vibration intensity function on the vertical axis in FIGS. 3 to 9 is a value related to the vibration intensity, but is an output of the FTT analyzer 15 when conditions such as the sensitivity of the measured value are constant, It is a value related to the vibration intensity.
The value is standardized by the TT analyzer 15 and is dimensionless.
In contrast, the concrete structure having the spectra of FIGS. 6 and 7 has a relatively complicated spectrum,
Near the z, the peak of the resonance frequency of the shear wave is gentle,
In addition, the vibration intensity function is also low. Further, the concrete structure having the spectrum shown in FIGS. 8 and 9 has a complicated resonance frequency spectrum, and the peak of the resonance frequency of the shear wave is not clear around 5 kHz. In particular, one of the features of this crack detection is that it is a clear detection means that a deep and sharp valley appears in the resonance frequency spectrum and cannot be obtained by other known deterioration measurement means.

From these facts, the method and apparatus for measuring the degree of deterioration of a concrete structure according to the embodiment of the present invention vibrate a reinforced concrete structure to be measured, measure a resonance frequency spectrum, and measure the internal structure of the reinforced concrete structure. Is determined based on the following criteria, and whether or not the part is sound is checked. (1) When the resonance frequency spectrum has a complex uneven, deep and sharp valley, and the peak of the resonance frequency of the inherent transverse wave due to the thickness is unclear → It is determined that there is a crack. (2) If the peak of the resonance frequency of the inherent shear wave due to the thickness of the resonance frequency spectrum is gentle and the vibration intensity function is low, it is determined that free lime is present. (3) If the above does not apply to (1) and (2), and the peak of the resonance frequency of the inherent transverse shear wave due to the thickness of the resonance frequency spectrum is clear and the vibration intensity function is high → it is determined to be a healthy part .

In the states (1), (2), and (3), an average resonance frequency spectrum of a sound part is created and used as a reference resonance frequency spectrum. Is determined by visual observation of the degree,
By calculating the degree of displacement quantitatively, the degree of deterioration of the internal structure of the reinforced concrete structure can be measured.

The specific configuration of the measuring device is as follows:
A known FTT analyzer 15 is used, and the shape calculation device is configured using a microcomputer including an input device, a calculation processing device, a storage device, an output device, and the like. Recall this reference resonance frequency spectrum, superimpose the measured resonance frequency spectrum measured in the above-described procedure on the display, and display the area where the measured resonance frequency spectrum is lower than the reference resonance frequency spectrum in red. In addition, the area outside the upper value is displayed in green, and the above (1) (2)
The degree of deterioration is visually determined from the screen by the operator based on the determination criteria of (3), or the degree of deviation is quantitatively calculated to determine the degree of deterioration inside the reinforced concrete structure. The configuration of the apparatus at this time may be appropriately selected from screen analysis software such as peak analysis software suitable for the above-described measurement method. Also,
If the comparison spectrum is output on paper via an output device such as a printer as needed, it can be used as objective deterioration degree data of a reinforced concrete structure, unlike a simple visual inspection of concrete.

In the first embodiment described above, the thickness
It is intended for structures with 0.23m concrete walls, roads and ceilings.Of course, concrete with a constant thickness other than 0.23m, for example, 1m thick concrete walls, roads,
For the ceiling structure, the average resonance frequency spectrum of the sound part is created in the same procedure as described above and used as the reference resonance frequency spectrum, and the measured resonance frequency spectrum of the measurement site is overlapped with the above (1) ( 2) The degree of deterioration of the internal structure of the reinforced concrete structure can be measured by visually determining the degree of deviation or quantitatively calculating the degree of deviation based on the criteria of (3). Further, even in a concrete structure having many places of the same geometric shape and dimensions, if the same thickness h is present, the spectrum becomes complicated, but for the same thickness h, a transverse wave in the thickness direction is generated. Since there is a reference resonance frequency of the longitudinal wave vibration mode, the measurement target is not limited to the floor plate, but to a concrete structure having the same geometric shape and dimensions, for example, a cubic or polyhedral concrete structure. Of course, it is applied.

[Embodiment 2] Next, a concrete embodiment of a concrete deterioration measuring method and a measuring apparatus by resonance frequency measurement according to the present invention will be described. At present, the relationship between the self-potential of the self-potential measurement method which has been relatively well-established and the phase velocity of the shear wave at the peak of the resonance frequency of the shear wave at around 5 kHz according to the present invention is analyzed. The result is shown in FIG. This will be described with reference to a graph and [Table 1] in FIG.

[Table 1] in FIG. 11 will be described. First, as described in the above (1), when the resonance frequency spectrum has a complex irregularity and a deep and sharp valley, and the peak of the resonance frequency of the shear wave is unclear, the cracks are seen at a glance without measuring. Was excluded from the comparison, but the compressive strength of the concrete X to be measured was very weak at σ = 238, and the degree of deterioration was clearly inferior. In addition, judgment of healthy part or free lime part,
A sample of the concrete at the site was collected and subjected to a compression test and the like, and further, the powder was analyzed for its composition to detect the degree of lime alteration.

In the above-mentioned method of measuring the natural potential, the possibility of corrosion of the steel material of the concrete structure is determined as follows: if the value of the natural potential mV is: (1) -200 mV <E, there is a probability of 90% or more of no corrosion. If -350mV <E ≤ -200mV, the degree of corrosion is uncertain. (3) If E ≤ -350mV, the probability of corrosion is 90% or more. Then, the natural potential in the natural potential measurement method for the reinforced concrete structure to be measured and the phase velocity of the shear wave at the peak of the resonance frequency of the shear wave near 5 kHz are expressed by the following equation: (1) The resonance frequency of the shear wave fs = vs / 2h FIG. 1 shows a comparison with a phase velocity value obtained by calculating back vs.
As shown in the graph of 0, a correlation was observed, and it was also confirmed that there was reliability. That is, in the graph of FIG. 10, it can be seen that the self-potential of the healthy part is located on the left side and above.

From the measurement results shown in [Table 1] in FIG.
When the shear wave phase velocity value vs (km / s) at the peak of the shear wave resonance frequency near 5 kHz is 1. (1) 2.25> vs (km / s), the amount of free lime is large and the free lime portion ( Y1 to Y6: Compressive strength of concrete σc = 270 (kg · f / cm2)) (2) If 2.25> vs (km / s)> 2.28, the degree of free lime is uncertain (3) vs (km If / s) ≥ 2.28, there is almost no free lime and it can be determined that the part is sound (Z1 to Z4: compressive strength of concrete σc = 288 (kg · f / cm2)). In order to make the above judgment as a more definitive judgment criterion in comparison with the result of the self potential measurement method,
Data Y6 and Z1 are (2) -350mV
<E ≦ −200 mV, and the degree of corrosion is in an uncertain range. In this range, if the degree of free lime is uncertain, the following 2. And become more qualified.

2. (1) In the case of 2.23> vs (km / s) (Y1 to Y5), the amount of free lime is large, and the free lime portion is (2) 2.23> vs (km / s) ≧ 2.44 (Y6, Z1) In the case of, the degree of free lime is uncertain. (3) In the case of vs (km / s) ≥ 2.44 (Z2 to Z4), there is almost no free lime and there is a healthy part.

As described above, the resonance frequency measuring method and the measuring apparatus according to the second embodiment vibrate a concrete structure to be measured, measure the resonance frequency of the concrete structure, and measure the thickness h: In the case of 0.23 m, the peak of the resonance frequency of the shear wave clearly appears around 5 kHz. The phase velocity value of the shear wave at the peak of the resonance frequency of the shear wave near 5 kHz is calculated, and the value of this phase speed vs (km / s) is (1) 2.25> vs (km / s)
In the case of 2.23> vs (km / s), more free lime is determined to be a free lime portion, and (2) 2.25> vs (km / s)> 2.
28, More preferably, if 2.23> vs (km / s) ≧ 2.44, the degree of free lime is determined to be indeterminate, and (3) vs (km / s)
In the case of ≧ 2.28, more preferably vs (km / s) ≧ 2.44, it is determined that there is almost no free lime portion and that it is a healthy portion. However, the resonance frequency measuring method of the second embodiment is based on (1) the resonance frequency of the transverse wave fs = vs / 2h (2) the resonance frequency of the longitudinal wave fp = vp / 2h Yes, if the thickness of the concrete structure to be measured changes from h: 0.23 m, the above-mentioned (1) resonance frequency of transverse wave fs = vs / 2h (2) resonance frequency of longitudinal wave fp = vp / 2h Also changes, the peak of the resonance frequency of the shear wave also moves from around 5 kHz. In each case, the reference resonance frequency value of the shear wave and the reference phase velocity value of the shear wave of the sound part at the thickness are set, and The degree of deterioration of the internal structure may be measured and determined in the same procedure as described above.

Then, the configuration of the above specific measuring device is as follows:
As in the first embodiment, the FTT analyzer 15 is used, and the shape calculation device is configured using a microcomputer including an input device, a calculation processing device, a storage device, an output device, and the like.
When the thickness of the concrete structure to be measured is h: 0.23 m, the peak of the shear wave resonance frequency is detected near 5 kHz, and the phase velocity of the shear wave at the peak of the resonance frequency vs.
Is detected, and its vs (km / s) value is calculated as 1. Or 2.
(1) When the amount of free lime is free lime, the degree of free lime is uncertain, and (3) There is almost no free lime and it is healthy Are displayed by classification, and the configuration of the apparatus at this time may be selected as appropriate from screen analysis software suitable for the above-described known measurement method. Also, if necessary, if the paper is output via an output device such as a printer, unlike the judgment of the visual appearance of concrete,
It can be used as objective degradation data of reinforced concrete structures.

In the second embodiment, the thickness
Although it was intended for 0.23m concrete wall-shaped, road-surface and ceiling structures, the same applies to concrete wall-shaped, road-surface and ceiling structures of almost constant thickness other than 0.23m. The average resonance frequency spectrum of the healthy part is created in the same procedure as the reference resonance frequency spectrum, and the phase velocity there is calculated and compared with the phase velocity in the healthy part to quantitatively determine the internal structure of the reinforced concrete structure. The degree of deterioration can be measured. Also, in the case of a concrete structure having many places of the same geometrical shape and dimensions, for example, a cube or a polyhedron, if the same thickness h is present, the spectrum becomes complicated. Since the reference resonance frequency exists in the transverse and longitudinal wave vibration modes in the vertical direction, the measurement target is not limited to the floorboard, but can be applied to concrete structures with the same geometric shape and dimensions. Of course.

It is needless to say that the present invention is not limited to the above-mentioned two embodiments unless the characteristics of the present invention are impaired. For example, as described above, the object to be measured is a floor plate in the embodiment. However, it is a matter of course that the concrete structure may have a geometric shape having the same thickness.
As for the thickness, it is of course possible to measure a concrete structure having a thickness other than 23 cm as a measurement target. In the above two cited examples, a transverse wave or a relatively low transverse wave-like resonance frequency (5 kHz) is measured. However, as a matter of course, a longitudinal wave or a relatively high longitudinal wave-like resonance frequency (8 kHz
Even in z), when the peak of the resonance frequency can be clearly determined depending on the target concrete structure or the measuring instrument, the measurement may be performed on a high frequency longitudinal wave or longitudinal wave vibration.

[0031]

As described above, according to the first and third aspects of the present invention, in a concrete structure having portions of substantially the same thickness, the soundness of the concrete structure to be measured in advance is determined. Excitation of the part to measure the resonance frequency, create a reference resonance frequency spectrum of the healthy part, and excite other measurement parts to measure the resonance frequency of the measurement part, and measure the resonance frequency spectrum of the measurement part. A method for measuring the deterioration of a reinforced concrete structure, which determines the degree of deterioration of the internal structure by analyzing the degree of deviation between the two resonance frequency spectra by superimposing the created two resonance frequency spectra, and a measuring device. Therefore, based on the Young's modulus, which is an element related to the compressive strength of concrete, non-destructive concrete structures, shallow parts and deep inside The degree of deterioration can be measured appropriately, and the cracks can also be measured appropriately, especially from the degree of complexity that is more complicated than the sound part spectrum, that is, deep and sharp valleys with complex irregularities From the resonance frequency spectrum where the part appears, easily measure the degree of cracking at the measurement location, the degree of liberation of the reinforcing steel from the concrete, and the degree of softening of the cement at the measurement location from the degree of the peak of the spectrum being dull. Is obtained.

According to the second and fourth aspects of the present invention, in a concrete structure having a portion having substantially the same thickness, a sound portion of the concrete structure to be measured is vibrated in advance. The reference resonance frequency of the fundamental mode of the vibration in the sound part is detected, the value of the reference phase velocity is calculated from the reference resonance frequency, and another measurement unit is vibrated to measure the vibration around the reference frequency. The peak of the resonance frequency is detected, the phase velocity value of the vibration is calculated from the resonance frequency of the measuring unit at the peak, the two phase velocity values are compared, and the difference value is analyzed to determine the degree of deterioration of the internal tissue. Because it is a method and a measuring device for measuring the deterioration of reinforced concrete structures, the surface and shallowness of concrete structures are non-destructive based on the Young's modulus, a factor related to the compressive strength of concrete. It is said that the degree of deterioration in the deeper parts inside as well as the parts can be easily measured quantitatively and appropriately, and the degree of deterioration of the internal structure of the reinforced concrete structure can be quantitatively determined by the value of the phase velocity of vibration. The effect is obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory view schematically illustrating a system of a measuring device used in a method for measuring deterioration of a concrete structure according to one embodiment of the present invention.

FIG. 2 is a perspective view of a floor panel model of a reinforced concrete structure.

FIG. 3 is a spectrum diagram of a resonance vibration frequency of a floor panel model.

FIG.

FIG. 5 is a spectrum diagram of a resonance vibration frequency of a sound part of a reinforced concrete structure to be measured.

FIG.

FIG. 7 is a spectrum diagram of a resonance vibration frequency of a free lime portion of a reinforced concrete structure to be measured.

FIG.

FIG. 9 is a spectrum diagram of a resonance vibration frequency of a crack in a reinforced concrete structure to be measured.

FIG. 10 shows the natural potential and 5 kHz in the method for measuring the natural potential.
A graph showing the relationship between the phase velocity of the shear wave at the peak of the resonance frequency of the shear wave near z,

FIG. 11 shows the natural potential and 5 kHz in the method for measuring the natural potential.
FIG. 6 is a diagram showing, as [Table 1], a relationship between a shear wave phase velocity and a peak of a shear wave resonance frequency near z.

[Explanation of symbols]

10: Reinforced concrete floor plate model or reinforced concrete to be measured 11: Impact hammer 12: Force detection pickup 13: Excitation detection signal 14: Preamplifier 15: FTT analyzer 151: First channel of FFT analyzer section 152: Same as above 2 channels 16 Acceleration pickup 17 Vibration detection signal 18 Charge amplifier 19 Peak reader 20 PC 21 Printer

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Yoshio Soriai 2-28-27 Kuromatsu, Izumi-ku, Sendai City, Miyagi Prefecture (72) Inventor Yoshiyasu Matsumura 5-9-9, Nagamachi, Taihaku-ku, Sendai City, Miyagi Prefecture 10-1003 F-term (Reference) 2E176 AA01 BB38 2F068 AA00 BB26 CC11 DD13 FF23 FF25 FF28 GG05 KK16 QQ00 QQ05 QQ10 QQ25 RR01 RR13

Claims (4)

[Claims] In a concrete structure having a portion having substantially the same thickness, a healthy part of a concrete structure to be measured is vibrated in advance to measure a resonance frequency, and a reference resonance frequency spectrum of the healthy part is created. At the same time, the other measuring unit is vibrated to measure the resonance frequency of the measuring unit, and the measuring unit resonance frequency spectrum is created. A method for measuring the deterioration of a reinforced concrete structure, characterized in that the degree of deterioration of the internal structure is determined by analyzing the degree of deterioration. 2. In a concrete structure having a portion having substantially the same thickness, a sound portion of a concrete structure to be measured is vibrated in advance to detect a reference resonance frequency of a fundamental mode of vibration in the sound portion. While calculating the value of the reference phase velocity from the reference resonance frequency, the other measurement unit is excited to detect a peak of the measurement unit resonance frequency of the vibration near the reference frequency, and from the measurement unit resonance frequency at the peak. A method for measuring deterioration of a reinforced concrete structure, comprising calculating a phase velocity value of vibration, comparing the two phase velocity values, and analyzing a difference between the two to determine a degree of deterioration of an internal structure. 3. In a concrete structure having a portion having substantially the same thickness, a healthy portion of the concrete structure to be measured is vibrated in advance to measure a resonance frequency, and a reference resonance frequency spectrum of the healthy portion is created. At the same time, the other measuring unit is vibrated to measure the resonance frequency of the measuring unit, and the measuring unit resonance frequency spectrum is created. A deterioration measuring device for a reinforced concrete structure, characterized in that the degree of deterioration of an internal structure is determined by analyzing the degree of deterioration. 4. In a concrete structure having a portion having substantially the same thickness, a sound portion of the concrete structure to be measured is vibrated in advance to detect a reference resonance frequency of a fundamental mode of vibration in the sound portion. While calculating the value of the reference phase velocity from the reference resonance frequency, the other measurement unit is excited to detect a peak of the measurement unit resonance frequency of the vibration near the reference frequency, and from the measurement unit resonance frequency at the peak. An apparatus for measuring deterioration of a reinforced concrete structure, comprising calculating a phase velocity value of vibration, comparing the two phase velocity values, and analyzing a difference value between the two to determine a degree of deterioration of an internal structure.