JP2014211333A - Detached survey method and device inside concrete - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a detached survey method and device inside concrete capable of solving the problem of a method focusing on a difference in the cycle of a conventional survey technology by improving an analysis method of a measurement waveform from the concrete surface, and improving survey accuracy by preventing an influence due to the magnitude of impact force.SOLUTION: The concrete surface 10 is struck by a steel ball 11, and a vibration waveform generated by the strike is measured by an accelerometer 12 and recorded in a survey device body 13. By software included in the survey device body 13, a measurement waveform is standardized by commonalizing the maximum value of an amplitude value. The absolute value of the amplitude value of the standardized measurement waveform is calculated, and an amplitude adding value is calculated by adding the absolute value within a fixed time period. The survey device body 13 compares the amplitude adding value with a reference value, and evaluates that a detachment portion 17 exists when the amplitude adding value becomes larger than the reference value.

Description

  The present invention relates to a method and apparatus for exploring delamination inside concrete in which the presence / absence and range of a delamination portion inside concrete in a concrete structure is explored.

  If a concrete structure is used for many years, initial defects such as cold joints and cracks may partially peel due to aging, and in the worst case, a fatal accident may occur, such as a defective part falling off. From now on, it is an effective means for maintaining and managing a concrete structure to periodically check the state of occurrence of deterioration by a nondestructive test that directly inspects the structure without breaking it. In addition, when abnormalities are found as a result of periodic inspections, repairs and reinforcements are carried out by various methods. The purpose of repair / reinforcement is to restore or improve the mechanical performance of members and structures, and is a measure that contributes to extending the life of structures. However, if the actual repair / reinforcement work is not carried out according to the plan / design due to poor work, etc., and there are defects such as delamination inside, it will be a cause of re-deterioration, etc. It is thought that it cannot be done. From now on, it is an effective means for maintenance management of concrete structures to carry out repair and reinforcement construction management by nondestructive testing.

  The exploration exploration inside a concrete structure (about 100 mm deep from the concrete surface) is generally an artificial exploration in which a hammer is struck and the presence or absence of an abnormality is judged from the vibration sound detected by the ear.

  In recent years, a separation exploration technique using a nondestructive inspection apparatus has also been developed.

  For example, there is a nondestructive inspection method and apparatus for hitting a concrete surface and comparing the measured frequency with the ideal natural frequency of the hit object (for example, see Patent Document 1).

  In addition, by striking a concrete structure and Fourier transforming the relationship between the intensity of the generated signal and the elapsed time of the signal, the spectrum is replaced with the relationship between the strength of the signal and the frequency, and the sampling data detected by the sensor There is a non-destructive diagnosis method and apparatus for determining a quality of a concrete structure by setting a threshold value and comparing the threshold value with measurement data (see, for example, Patent Document 2).

  Furthermore, the average value of the intensity of the impact sound at the initial stage among the transient phenomena from the occurrence of the impact sound to the decay is struck, and the calculated average value is compared with a preset reference value. There is a concrete soundness evaluation method and apparatus evaluated by the above (for example, see Patent Document 3).

JP 2002-340869 A JP 2008-020425 A JP 2003-057217 A

  The exploration techniques disclosed in Patent Document 1 and Patent Document 2 are based on the period (frequency, vibration) between a flexural vibration that occurs when a peeling portion exists inside concrete and a longitudinal elastic wave or Rayleigh wave that occurs when sound is healthy. This method is general, but even if there is a peeled part, the period (frequency, frequency) may be the same depending on the position and size of the part. . Further, the exploration technique disclosed in Patent Document 3 has a problem of being affected by the strength of the striking force. For this reason, none of the conventional exploration techniques can provide reliable exploration accuracy.

  The present invention has been made in view of the above points, and has improved the analysis method of the measurement waveform from the concrete surface to solve the problem of the method focusing on the difference in the period of the conventional exploration technique, and the impact force. It is an object of the present invention to provide a method for exploring delamination inside concrete and an apparatus therefor that can improve the exploration accuracy by eliminating the influence of strength.

  According to the first aspect of the present invention, when there is a peeling portion inside the concrete of the concrete structure, flexural vibration due to flexure occurs, and when the concrete interior is healthy, longitudinal elastic waves and Rayleigh waves are generated, and flexural vibration occurs. Is a method for exploring delamination inside concrete that uses a characteristic that has a larger amplitude value than longitudinal elastic waves and Rayleigh waves. By applying striking force to the concrete surface, the vibration waveform generated by this striking is measured and recorded. Then, this measurement waveform is standardized by sharing the maximum value of the amplitude value, the absolute value of the amplitude value of this standardized measurement waveform is calculated, and the absolute value is added within a certain time to calculate the amplitude addition value Then, this amplitude addition value is compared with a reference value, and when the amplitude addition value becomes larger than the reference value, the peeling exploration method inside the concrete evaluates that there is a peeling portion.

  In the invention described in claim 2, when there is a peeling portion inside the concrete of the concrete structure, flexural vibration due to flexure occurs, and when the concrete interior is healthy, longitudinal elastic waves and Rayleigh waves occur, and flexural vibration occurs. Is a delamination exploration device inside concrete that uses a characteristic with a large amplitude compared to longitudinal elastic waves and Rayleigh waves, and is an impact instrument that strikes the concrete surface and an accelerometer that measures the vibration waveform generated by this impact And record the measurement waveform measured by this accelerometer, standardize this measurement waveform by sharing the maximum value of the amplitude value, calculate the absolute value of the amplitude value of this standardized measurement waveform, and within a certain time The absolute value is added to calculate the amplitude addition value, and this amplitude addition value is compared with the reference value. If this amplitude addition value becomes larger than the reference value, it is evaluated that there is a peeling portion. It is a concrete internal peeling exploration device including a portable locator body for.

  According to the first aspect of the present invention, a striking force is applied to the concrete surface, a vibration waveform generated by the striking is measured and recorded, and the measurement waveform is standardized by sharing the maximum value of the amplitude value. When the amplitude addition value is calculated by adding the absolute value of the amplitude value of the standardized measurement waveform within a certain time, and this amplitude addition value is compared with the reference value. Since it is evaluated that there is a peeling part, focusing on the amplitude of the measurement waveform can eliminate the problem of the method focusing on the difference in the period (frequency, frequency) of the conventional exploration technique, and the amplitude value of the measurement waveform By performing standardization at the maximum value and evaluation using the amplitude addition value, it is possible to eliminate the influence of the strength of the striking force, thereby improving the search accuracy. Furthermore, objective evaluation is possible compared to artificial delamination exploration techniques, and year-to-year comparison is possible by data recording.

  According to the second aspect of the present invention, the peeling exploration method in the concrete according to the first aspect can be easily carried out by the peeling exploration device including the hitting tool, the accelerometer, and the portable exploration device main body.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram which shows one Embodiment of the peeling exploration method and the apparatus for the concrete inside which concern on this invention, (a) is a schematic diagram in case a longitudinal elastic wave and a Rayleigh wave generate | occur | produce, (b) is bending It is a schematic diagram in case a vibration generate | occur | produces. It is a characteristic view which shows an example of the measurement vibration in a specimen, and a frequency analysis result. It is a graph which shows the comparison of the frequency fmax from which an amplitude becomes the maximum under each measurement condition. It is a graph which shows the comparison of the amplitude addition value Ys on each measurement condition. It is a histogram of the frequency fmax where the amplitude of all measured values becomes the maximum. It is a histogram of the amplitude addition value Ys of all the measured values. It is a distribution map which shows the measurement result of the frequency fmax where the amplitude in all the measurement points becomes the maximum. It is a distribution map which shows the measurement result of the amplitude addition value Ys in all the measurement points.

  Hereinafter, the present invention will be described in detail based on the embodiments supported by the measurement or experiment shown in FIGS.

  Detachment between base material concrete and repair / reinforcement material, such as cross-section repair method, thickening method, concrete winding method, etc. A method for inspecting the surface by the shock elastic wave method is examined. At that time, the repair / reinforcement material was assumed to be polymer cement mortar (hereinafter referred to as PCM) having a thickness of about 20 mm to 100 mm.

  First, it was confirmed by test specimen experiments how the measurement value of the shock elastic wave method changes depending on the peeling condition between the base material concrete and PCM, and the inspection method and application conditions were examined. In addition, measurements were made on actual bridges that were 15 years after reinforcement by the bottom surface thickening method, and the inspection method for the peeling condition between the base concrete and PCM, which was examined by test specimen tests, was verified.

(Measurement principle and outline of experiment)
FIG. 1 (a) shows a delamination exploration device inside concrete used for inspecting or measuring the delamination state between the base material concrete and PCM in a concrete structure in which PCM having a thickness of several tens of mm is bonded to the base material concrete. This exfoliation exploration device shows a steel ball 11 as a striking tool that strikes the concrete surface 10, an accelerometer 12 that detects and measures a vibration waveform generated by this striking, and detects by this accelerometer 12 A surveying device main body 13 having a portable analysis function for recording the measured measurement waveform and performing the arithmetic processing described below to evaluate the presence or absence of the peeling portion is provided. The exploration device body 13 is integrally provided with a personal computer function unit 13b having a display unit 13a.

  And the measuring method installs the accelerometer 12 on the surface of PCM, measures the vibration waveform which generate | occur | produces when the PCM surface of the adjacent position adjacent to the accelerometer 12 is hit | damaged with the steel ball 11, and the search apparatus main body 13 However, the built-in software performs arithmetic processing focusing on the amplitude of the measured waveform, and evaluates the PCM peeling state.

  First, with reference to the schematic diagram of FIG. 1, the influence of the presence of a void such as a peeling portion inside the concrete of the concrete structure on the vibration generated by striking the steel ball 11 will be described.

  As shown in FIG. 1 (a), when there is no peeling portion inside the concrete, the longitudinal elastic wave 14 propagating spherically inside the concrete is reflected by the concrete surface 10 and the reflecting surface 15 such as the back surface. It repeats or propagates on the concrete surface 10 so that the Rayleigh wave 16 draws an ellipse in the vertical direction.

  On the other hand, as shown in FIG. 1B, when the peeling portion 17 exists in the concrete, and the input wavelength due to the impact of the steel ball 11 becomes longer than the depth to the peeling portion 17, Then, vibration due to the deflection 18 of the peeling portion 17 (hereinafter referred to as flexural vibration) occurs.

The frequency generated by the longitudinal elastic wave 14 that repeats reflection on the concrete surface 10 and the reflecting surface 15 in FIG. 1A is a frequency fo shown in the equation [Equation 1]. Further, if the cross-sectional shape of the peeling portion 17 in FIG. 1B is a circle, the frequency generated by the flexural vibration is the frequency fmn shown in the equation [2].

  Here, Vp is the propagation velocity of the longitudinal elastic wave 14, D is the depth of the longitudinal elastic wave 14 to the reflecting surface 15, E is the longitudinal elastic modulus, ρ is the density, ν is the Poisson's ratio, and h is the separation part 17. Depth, a is a radius of the peeling portion 17, and Rmn is an eigenvalue that forms a flexural vibration.

  As described above, the type and frequency of vibration to be measured change depending on whether or not there is a gap such as the peeling portion 17 in the concrete, and if these changes are noted, the PCM and the base material concrete The peeling condition can be inspected.

  Therefore, first, PCM plates with different thicknesses were manufactured as test specimens, and vibrations measured when in close contact with concrete test specimens were compared, and the inspection method and application conditions by the shock elastic wave method were compared. investigated.

  In addition, measurements were made on actual bridges that were 15 years after reinforcement by the bottom surface thickening method, and the inspection method for the peeling condition between the base concrete and PCM, which was examined by test specimen tests, was verified.

The PCM used is a polyacrylate copolymer resin-based special polymer cement mortar, polymer / cement ratio = 12%, W / C = 32%, and the standard value of compressive strength at the age of 28 days in standard curing is 30. It is an ON / mm ^2. The accelerometer 12 used for the measurement by the shock elastic wave method is a piezoelectric accelerometer (sensitivity 10 mV / (m / s ² ), frequency range 0.3 Hz to 12 kHz), and the sampling interval is 10 μs. The frequency analysis method for measurement vibration was the maximum entropy method.

(Experimental result of specimen)
The outline of the experiment using the specimen was a PCM plate having a length x width of 300 mm x 300 mm and thicknesses of 20 mm, 52 mm, and 102 mm different from each other. Using the central position of these PCM plates as a measurement point, vibration generated by hitting a steel ball 11 having diameters of 10 mm, 15 mm, and 20 mm was measured. This measurement was performed in a state in which the PCM plate was not in close contact with the concrete specimen and in a state in which the PCM plate was in close contact with a water-stopping material mainly composed of an ultrafast hard inorganic compound. The concrete specimen has a shape of 870 mm × 900 mm × thickness 300 mm, W / C = 48.0%, and the compressive strength at the age of 28 is 36.2 N / mm ² . Moreover, the water-stopping material used the 15-35 minute hardening time type, and measured it 2 hours after making a PCM board adhere to a concrete test body.

(1) Examination by frequency analysis FIG. 2 shows an example of measured vibration and frequency analysis results under each condition, and FIG. 3 shows the frequency fmax having the maximum amplitude in all frequency analysis results.

  Focusing on the measurement results before adhesion, the frequency fmax was 4.7 kHz for a 20 mm thick PCM plate, 5.0 kHz for 52 mm, and 6.4 kHz for 102 mm, regardless of the diameter of the steel ball 11. The frequency fmax before adhesion increases as the thickness of the PCM plate increases. This is a result consistent with the fact that the frequency due to the flexural vibration shown in the equation [2] varies depending on the depth to the peeling portion 17, that is, the thickness of the PCM plate. From this, it is considered that the flexural vibration was measured on the PCM plate before adhesion regardless of the diameters of the steel balls 11 of 10 mm, 15 mm and 20 mm for the thicknesses of 20 mm, 52 mm and 102 mm.

  Next, it can be seen that the frequency fmax after adhesion changes from that before adhesion, regardless of the diameter of the steel ball 11, for thicknesses of 20 mm, 52 mm, and 102 mm. From this, it is considered that vibrations other than the flexural vibration due to the flexure 18 were measured after the contact. However, the measured frequency fmax varies depending on the diameter of the steel ball 11, and the frequency due to multiple reflection represented by the equation [Equation 1] is not always measured. Specifically, the frequency due to multiple reflection on both the PCM plate and the concrete specimen is 20 mm in thickness (total thickness 320 mm) according to the formula [1], assuming that the longitudinal elastic wave velocity is 4000 m / s. This PCM plate is 6.3 kHz, 52 mm is 5.7 kHz, and 102 mm is 5.0 kHz, but this frequency was measured with 52 mm and 102 mm thick PCM plates with a steel ball 11 diameter of 20 mm. Only if. In addition, looking at how the measured frequency fmax changes before and after the adhesion, only the thickness of 102 mm and the diameter of the steel ball 11 is 20 mm. It can be seen that the content of the change in the frequency fmax due to the adhesion varies depending on conditions such as the thickness of the PCM plate and the diameter of the steel ball 11 to be measured.

  As shown in FIG. 1, these causes are that a plurality of vibrations such as the Rayleigh wave 16 are generated in the measurement by hitting the steel ball 11, and therefore the measured frequency fmax varies depending on the diameter of the steel ball 11 to be measured. by. That is, the frequency band of the input vibration varies depending on the diameter of the steel ball 11 to be measured, but the measured frequency fmax is a vibration frequency that approximates the frequency band of the input vibration.

  From the above results, it is difficult to predict the frequency fmax measured when the PCM and the base concrete are in close contact. Further, the frequency of flexural vibration measured when the peeling portion 17 is present varies depending on the depth to the peeling portion 17 and the cross-sectional dimension of the peeling portion 17. From these, depending on conditions such as the shape and position of the peeled portion 17 and the diameter of the steel ball 11 to be measured, the frequency measured when closely attached may coincide with the frequency due to flexural vibration. In other words, it is considered that in the hammering test for determining the presence or absence of deformation with the human ear, the determination is made by paying attention to the change in the frequency of the generated vibration. It is considered that there is a case where the determination of the state of peeling from concrete is wrong.

(2) Examination Focusing on Amplitude Value of Measured Vibration Focusing on the attenuation of the measured vibration over time shown in FIG. 2, it is confirmed that there is a difference before and after contact. This is thought to be due to the fact that flexural vibration has a narrower propagation range of vibration and energy loss than other vibrations. Therefore, the amplitude addition value Ys under each measurement condition was calculated by the equation [Equation 3] and compared.

  Here, y (t) is the amplitude value of the measurement waveform at time t, and is a relative amplitude value standardized by the maximum value within the measurement time in order to eliminate the influence of the impact strength.

  In other words, since the amplitude value of the recorded measurement waveform changes depending on the strength of the striking force, the influence of the difference due to the striking force is eliminated by standardizing the maximum amplitude value. Further, if standardized, the maximum value of amplitude is common to all measurement points, and the occurrence of flexural vibration due to the deflection 18 cannot be confirmed with the standardized maximum value of amplitude. Therefore, the absolute value of the amplitude value of the standardized measurement waveform is calculated, and the amplitude absolute value Ys is calculated by adding the absolute value within a predetermined time, and this amplitude added value Ys is compared with the reference value. This is a method for extracting the occurrence of flexural vibration in which the amplitude addition value Ys is larger than the reference value.

  A comparison of the amplitude addition value Ys under each measurement condition is shown in FIG. Regardless of the thickness of the steel ball 11 in the thicknesses of 20 mm, 52 mm, and 102 mm, the PCM plate and the concrete specimen are in close contact with each other, so that no bending vibration is observed, and the amplitude addition value Ys is extremely small. I understand that

  From the investigation by frequency analysis in (1), there is a possibility that the judgment result of the peeling state between PCM and base material concrete is wrong in comparison by frequency analysis. On the other hand, the amplitude addition value Ys showed a change that becomes remarkably small due to the contact, regardless of the thickness of the PCM plate or the diameter of the steel ball 11. From this, it is considered that the amplitude addition value Ys becomes a measurement value effective for evaluation of the peeling state.

(Experimental results for actual structures)
The outline of the experiment in the actual structure will be explained. If the PCM and the base material concrete are separated from each other, the flexural vibration due to the flexure 18 is generated and the amplitude is maximized in the frequency analysis result. It was confirmed that the frequency fmax and the amplitude addition value Ys change. In order to verify these with actual structures, an experiment was conducted on two road bridges (A and B bridges) constructed in the Showa 40s and reinforced by the underside thickening method in 1995.

  These A and B bridges are thickened to a thickness of about 20 mm by PCM of the same material as in the specimen experiment. The base concrete of the floor slab has a thickness of about 150 mm, and the composition of the concrete used is unknown. When the longitudinal elastic wave velocity was measured by the propagation time difference method of the shock elastic wave method on the side surface of the base material concrete, it was 3886 m / s for the A bridge and 3888 m / s for the B bridge. Measurement points were set in a grid pattern at intervals of 50 mm in the bridge axis direction and the transverse direction, and measurement was performed at 5 points × 10 points on the A bridge and 7 points × 9 points on the B bridge. The diameter of the steel ball 11 used for these measurements is 10 mm.

(1) Examination of determination method In the above experimental results, it has been confirmed that the frequency fmax and the amplitude addition value Ys at which the amplitude is maximum change in the frequency analysis result. However, it is not possible to set a quantitative determination reference value. Not done. Therefore, there is no significant difference in the thickness of the A and B bridge members, the PCM material used, the PCM thickness, and the longitudinal elastic wave velocity. The criteria were set by FIG. 5 and FIG. 6 and Table 1 show the calculation results of the histogram (frequency distribution diagram) of all the measured values, the average value m, and the standard deviation σ.

  From the above experimental results, it is conceivable that the frequency fmax having the maximum amplitude may be higher or lower than the frequency of the flexural vibration of the peeling portion 17 when in close contact. In addition, it has been confirmed that the amplitude addition value Ys is smaller when closely attached than when the peeling portion 17 is present. From these, the calculation result of the average value m, and the standard deviation σ, it is considered that the data 3σ away from the average value m is an abnormal value, and the frequency fmax at which the amplitude is maximum is out of the range of 8.5 kHz to 17.6 kHz. If the amplitude addition value Ys is 32.0 or more, a determination reference value is set as an abnormal value.

(2) Measurement results The measurement results and determination results of the frequency fmax at all measurement points of the A bridge are shown in FIG. 7 and Table 2, and the measurement results and determination results of the amplitude addition value Ys at all measurement points of the A bridge are shown in FIG. FIG. 8 and Table 3 show. 7 and Table 2 are comparisons by period (frequency, frequency), and FIG. 8 and Table 3 are comparisons focusing on the amplitude of the measured waveform.

  From the measurement results, the A bridge was determined to be an abnormal value at 2 measurement points at the frequency fmax at which the amplitude was maximum, and at 3 measurement points at the amplitude addition value Ys. At the measurement point in the bridge axis direction of 750 mm and the transverse direction of 200 mm, the frequency fmax is a normal value and the amplitude addition value Ys is an abnormal value, and the determination results by both do not match. That is, in comparison by period (frequency, frequency), it is not possible to search for anomalies in the bridge axis direction of 750 mm and the transverse direction of 200 mm.

  The reason why the judgment results do not match is that the frequency of the flexural vibration caused by the peeling portion 17 varies depending on the depth position where the peeling portion 17 is generated and the cross-sectional dimension of the peeling portion 17 as shown in the equation [2]. Therefore, it is conceivable that the determination by the frequency fmax could not be determined as an abnormal value because it coincided with the frequency within the determination criterion.

Here, from the equations [Equation 1] and [Equation 2], the condition that the frequency fo due to multiple reflection coincides with the frequency fmn due to flexural vibration is the condition of the equation [Equation 4]. Assuming a first order flexural vibration with a Poisson's ratio ν of 0.2 and Rmn = 1, the equation of [Equation 5] is obtained from the equation of [Equation 4].

  The bridge A has a PCM thickness of 20 mm, and the depth h to the peeling portion 17 can be set to 20 mm.

  The depth D to the reflection surface 15 due to multiple reflection is about 150 mm from the thickness of the floor slab. By substituting these into the equation of [Equation 5], if the radius a of the peeling portion 17 is 23 mm, the frequency due to multiple reflections coincides with the frequency due to flexural vibration. Furthermore, since the determination reference value is a normal value with a frequency of ± 3σ from the average value m, the condition that the bending vibration is not determined as an abnormal value is wider than the condition where the radius a of the peeling portion 17 is 23 mm. become.

  From the above results, the presence or absence of separation between the PCM and the base concrete may not be accurately determined at the frequency fmax, and it is considered appropriate to determine based on the amplitude addition value Ys.

(Summary)
A method of confirming the peeling state between PCM and base material concrete in the bonding method by a shock elastic wave method which is a nondestructive inspection was examined. The obtained results are shown below.

  (1) When a 20mm, 52mm, or 102mm thick PCM plate is changed without being in close contact with a concrete specimen, it is confirmed that flexural vibration is generated by the impact of steel balls 11 with a diameter of 10mm, 15mm, and 20mm. It was done.

  (2) The frequency of flexural vibration varies depending on the position where the peeling portion 17 is generated and the cross-sectional dimensions. Further, the frequency measured when the PCM and the base material concrete are in close contact changes depending on conditions such as the diameter of the steel ball 11 to be struck. From these, it is conceivable that the frequency measured when the PCM and the base concrete are in close contact with the frequency due to the flexural vibration in the case where the PCM is not in close contact.

  (3) The flexural vibration has a small amplitude attenuation over time. From this, the amplitude addition value Ys shows a change that becomes remarkably small due to the close contact between the PCM plate and the concrete specimen, regardless of the thickness of the PCM plate or the diameter of the steel ball 11 to be hit.

  (4) From the above (2) and (3), there is a case where the judgment of the peeling state between the PCM and the base material concrete is wrong in the comparison only by the frequency. On the other hand, the amplitude addition value Ys is considered to be a measurement value effective for determination. Actually, when measuring with an actual structure after 15 years of reinforcement by the bottom surface thickening method, it was confirmed that accurate judgment might not be possible due to the cause shown in (2) in comparison by frequency. It is appropriate to make a determination based on the amplitude addition value Ys.

  As described above, it was confirmed that the peeling state between the PCM having a thickness of about 20 mm to 100 mm and the base material concrete can be objectively evaluated by using the measured vibration amplitude addition value Ys. Further, in this method, since the measurement value can be recorded in the apparatus, it is possible to visually grasp the measurement result and to confirm the secular change, which is an effective inspection method in the maintenance management of the concrete structure.

  Based on the above points, this peeling exploration method generates flexural vibration due to the deflection 18 when the peeling portion 17 is present inside the concrete. On the other hand, when the peeling portion 17 does not exist inside the concrete, the method of longitudinal elasticity Using the principle that the wave 14 and Rayleigh wave 16 are generated and the flexural vibration has a larger amplitude value than the longitudinal elastic wave 14 and Rayleigh wave 16, the concrete surface 10 is hit by the steel ball 11 The vibration waveform generated by the impact is measured by the accelerometer 12 and recorded in the exploration device main body 13. The software built in the exploration device main body 13 standardizes the measurement waveform by sharing the maximum amplitude value, The absolute value of the amplitude value of the standardized measurement waveform is calculated, and the amplitude absolute value Ys is calculated by adding the absolute value within a predetermined time, and the amplitude added value Ys is compared with the reference value to obtain the amplitude. Addition value Ys is standard There is peeling portion 17 when the larger, otherwise evaluates that there is no peeling section 17.

  And by focusing on the amplitude of the measurement waveform, it is possible to eliminate the problem of the method of focusing on the difference in the period (frequency, frequency) of the conventional exploration technique, and to standardize the maximum amplitude value of the measurement waveform, By performing the evaluation based on the amplitude addition value Ys, it is possible to eliminate the influence due to the strength of the striking force, thereby improving the search accuracy. Furthermore, objective evaluation is possible compared to artificial delamination exploration techniques, and year-to-year comparison is possible by data recording.

  INDUSTRIAL APPLICABILITY The present invention has industrial applicability for business operators involved in construction and maintenance of concrete structures.

10 Concrete surface
11 Steel balls as striking tools
12 Accelerometer
13 Exploration equipment
14 Longitudinal elastic wave
16 Rayleigh waves
17 Peeling part
18 Deflection

Claims (2)

If there is an exfoliation part inside the concrete of a concrete structure, flexural vibration due to flexure occurs, and if the concrete interior is healthy, longitudinal elastic waves and Rayleigh waves are generated, and flexural vibration is compared with longitudinal elastic waves and Rayleigh waves. A method for exploring delamination inside concrete using a characteristic having a large amplitude value,
Apply striking force to the concrete surface, measure and record the vibration waveform generated by this striking,
Standardize this measurement waveform by sharing the maximum amplitude value,
Calculate the absolute value of the amplitude value of this standardized measurement waveform,
Add the absolute value within a certain time to calculate the amplitude addition value,
A method for exploring delamination inside concrete, wherein the amplitude addition value is compared with a reference value, and evaluation is made that there is delamination when the amplitude addition value is greater than the reference value. If there is an exfoliation part inside the concrete of a concrete structure, flexural vibration due to flexure occurs, and if the concrete interior is healthy, longitudinal elastic waves and Rayleigh waves are generated, and flexural vibration is compared with longitudinal elastic waves and Rayleigh waves. A delamination exploration device inside concrete that uses a characteristic with a large amplitude value,
An impact tool for striking the concrete surface;
An accelerometer that measures the vibration waveform generated by this impact,
Record the measurement waveform measured by this accelerometer, standardize this measurement waveform by sharing the maximum value of the amplitude value, calculate the absolute value of the amplitude value of this standardized measurement waveform, and calculate the above absolute value within a certain time A portable exploration device body that calculates an amplitude addition value by adding the values, compares the amplitude addition value with a reference value, and evaluates that there is separation when the amplitude addition value becomes larger than the reference value. A delamination exploration device inside concrete characterized by comprising.

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