JP5562118B2 - Ultrasonic nondestructive measuring method, ultrasonic nondestructive measuring device, and program - Google Patents

Description

  The present invention relates to a technique for measuring the ultrasonic propagation velocity of a concrete structure, and in particular, an ultrasonic nondestructive measurement method, an ultrasonic nondestructive measurement device, and a program for measuring the ultrasonic propagation velocity of a concrete structure by a reflected wave method. About.

  In concrete structures such as bridges, tunnels, retaining walls, etc., nondestructive inspection equipment using ultrasonic waves is used for the purpose of soundness diagnosis against construction quality control and deterioration deformation. General inspection items include crack depth (depth of cracks going from the surface of the concrete structure to the inside), internal crack depth (cracks existing inside the concrete structure from the surface of the concrete structure, etc.) Measurement of the thickness of concrete structures is known.

  The Architectural Institute of Japan “Non-destructive testing method manual for concrete strength estimation (1983.2)” shows that there is a correlation between the ultrasonic propagation velocity and compressive strength in concrete structures. For example, as shown in FIG. 16, for example, as shown in FIG. 16, it is possible to estimate the compressive strength by measuring the velocity of ultrasonic waves (ultrasonic propagation velocity) in concrete.

  For the measurement of the ultrasonic propagation velocity, the transmission probe 4 shown in FIG. 14A and the reception probe 5 shown in FIG. 14B are used. The transmission probe 4 includes a voltage generator 41 inside, and the voltage generator 41 generates a voltage for generating an ultrasonic wave by a control signal given from the outside. The reception probe 5 includes a receiver 51 inside, and the receiver 51 converts the vibration as a received signal as a voltage waveform and sends it to the outside. The contact media 42 and 52 are made of, for example, glycerin paste or grease interposed between the vibrator and the concrete structure 1.

  In the estimation of the compression strength based on the ultrasonic wave propagation speed in Non-Patent Document 1, a “transmission method” as shown in FIG. In the transmission method, the transmission probe 4 and the reception probe 5 are arranged with the concrete structure 1 sandwiched between them when the ultrasonic wave propagation speed is obtained from the reception signal from the reception probe 5. 1, the ultrasonic wave propagation speed (hereinafter referred to as “transmitted sound speed”) can be calculated from the thickness of the concrete structure 1 by measuring the time of propagation through the ultrasonic wave.

  On the other hand, in the “surface method” as shown in FIG. 15 (b), the transmission probe 4 and the reception probe 5 are arranged on the surface of the concrete structure 1, and ultrasonic waves propagate on the surface of the concrete structure 1. Thus, by determining the arrival time, the ultrasonic propagation velocity (hereinafter referred to as “surface sound velocity”) can be calculated.

  These transmission methods and surface methods are methods for measuring the ultrasonic propagation velocity of typical concrete structures, but the surface sound velocity represents the surface properties, and the transmitted sound velocity representing the internal properties of the concrete structure. Is different in nature. In other words, when performing nondestructive inspection using ultrasonic waves on the concrete structure itself, in general, not only the compressive strength of the concrete structure, but also the crack depth, internal crack depth, and thickness of the concrete structure 1 are determined. It is recommended to use the transmission method to measure.

  Separately from the transmission method and the surface method described above, the transmission probe 4 and the reception probe 5 are arranged on the surface of the concrete structure 1 at a predetermined interval, and the transmission probe 4 extends from the surface of the concrete structure to the bottom surface. The reception probe 5 detects the component of the ultrasonic wave reflected from the bottom of the concrete structure as a received signal, and measures the arrival time of the reflected wave in the concrete structure 1 from the voltage waveform of the received signal. A technique for calculating the speed of sound wave propagation (hereinafter referred to as “reflected wave method”) is known (see, for example, Patent Document 1). In particular, the technique of Patent Document 1 measures the reflected wave arrival time in a concrete structure by “superimposed wave filtering processing” for obtaining the intersection coordinate time from the smoothness of the peak time position of the ultrasonic reception signal, and measures the concrete to be measured. The ultrasonic wave propagation velocity of the structure (hereinafter also referred to as “reflection sound velocity”) is determined. However, this method assumes that the thickness of the structure is an existing value.

Japanese Patent No. 4308719

Edited by the Architectural Institute of Japan, “Non-destructive testing method manual for estimating concrete strength”, published by the Architectural Institute of Japan, Maruzen Co., Ltd., June 25, 1983 (1st edition, 2nd print), p. 29, 39

(First problem) Structure dependency of the structure to be measured When measuring the transmitted sound velocity by the transmission method, the probe is placed with a concrete structure sandwiched between two probes, a transmission probe and a reception probe. Although it is necessary, it is impossible to place a probe on the ground in the measurement of underground structures such as tunnels and manholes. In the case of the transmission method, since it is assumed that the thickness of the concrete structure is known, if the thickness of the concrete structure cannot be measured, the transmitted sound velocity cannot be measured.

  When the surface sound velocity is measured by the surface method, the ultrasonic wave propagating through the surface of the concrete structure is measured, so that it is different from the transmitted sound velocity propagating through the concrete structure as in the transmission method. The surface of existing concrete structures often has fine cracks, and the coarse aggregate (gravel) is slightly less, so the surface sound speed is lower than the transmitted sound speed, and the surface sound speed is not stable. Is significantly reduced.

  Further, even in the reflected wave method in the technique of Patent Document 1, if the surface of an existing concrete structure is finely cracked, there is a possibility that the reflected wave arrival time in the concrete structure to be measured is erroneously measured. In some cases, it was necessary to core a part of the concrete structure to be measured and to measure the sound velocity transmitted through the sampling core.

(Second problem) Dependence of concrete structure on concrete material Concrete material determines the amount of cement, water, aggregate and gravel at the time of production, but strictly speaking, the composition of the concrete material is not uniform. It is. This non-uniform composition in the concrete material erroneously measures the propagation time of ultrasonic waves in the concrete structure to be measured in any of the transmission method, the surface method, and the reflected wave method in the technique of Patent Document 1. there is a possibility.

  Typically, FIG. 17 shows an example in which the reflected wave arrival time in the concrete structure to be measured is erroneously measured for the reflected wave method in the technique of Patent Document 1. FIGS. 17A and 17B show examples of measuring the propagation time of ultrasonic waves in the concrete structure 1 including aggregates and the like. FIG. 17A shows a case where the reception probe 5 detects, as a reception signal, a component reflected by the bottom surface of the concrete structure 1 by the ultrasonic wave from the transmission probe 4 without being affected by the aggregate ( FIG. 17 (a) shows the left side), and shows that the received signal can be obtained as a simple reflected waveform and the ultrasonic propagation time Ta is correctly obtained (right side shown in FIG. 17 (a)). FIG. 17B is affected by the aggregate, and the component (normal component) in which the ultrasonic wave from the transmission probe 4 is reflected from the bottom surface of the concrete structure 1 and the component (noise) reflected from the aggregate. Is detected by the reception probe 5 (shown on the left side of FIG. 17B), the ultrasonic wave propagation time Ta cannot be correctly obtained as a reflected waveform with noise superimposed, and has an error ΔT. The state of obtaining the ultrasonic propagation time Ta ′ is shown (shown on the right side of FIG. 17B).

  As shown in FIG. 17B, when a minute reflected wave is superimposed, the reflected wave spectrum becomes rough, and the superimposed minute reflected wave becomes noise. As the amount of noise increases, the reflected wave spectrum becomes coarser and the reflected wave from the thickness of the concrete structure 1 becomes unclear. For this reason, in a rough reflected wave spectrum, there is a possibility that the reflected wave from the thickness of the concrete structure 1 and the arrival time T (regular ultrasonic wave propagation time Ta) may be mistaken. And when the thickness of the concrete structure 1 and the speed of sound in the concrete structure 1 are calculated using the arrival time T (error detection ultrasonic propagation time Ta ′) having an error, these naturally also have an error. Value.

  Therefore, even in this case, it may be necessary to core a part of the concrete structure to be measured and to measure the transmitted sound speed of the sampled core.

  The object of the present invention has been made in view of the above problems, an ultrasonic nondestructive measurement method, an ultrasonic nondestructive measurement device, which measures the ultrasonic propagation velocity of a concrete structure with a reflected wave method with high accuracy, And providing a program.

  As an outline, the present invention performs waveform analysis by changing the installation distance and the installation position of a pair of transmission probes and reception probes (hereinafter also simply referred to as “probes”), and the bottom surface of a concrete structure. The reflected wave arrival time is calculated so as to minimize the measurement error of the reflected wave from and the ultrasonic wave propagation speed inside the concrete structure is determined.

That is, the ultrasonic nondestructive measuring apparatus of the present invention uses the transmission probe and the reception probe arranged at a predetermined interval on the surface of the concrete structure to measure the ultrasonic propagation velocity of the concrete structure by the reflected wave method. An ultrasonic nondestructive measuring device for measuring, wherein the ultrasonic wave generating means controls to generate ultrasonic waves from the transmission probe, and the reception reflected from the bottom surface of the concrete structure from the reception probe. A reception signal processing unit that controls to acquire a signal as a reception signal waveform starting from the generation time of the ultrasonic wave, and frequency analysis is performed on the reception signal waveform to determine whether the signal is a single frequency signal and a frequency analyzing means for determining whether the received signal noise is superimposed, from the received signal waveform, the received signal waveform of the reception signal received signal waveform that to calculate the midpoint of the waveform intermediate based on the amplitude Reflection determining means, said single frequency and reflection time calculated from the midpoint of the received signal waveform thus noise on the frequency analysis hand stage is determined not to be superimposed regular in the concrete structure Reflected wave arrival time determining means to determine the ultrasonic wave propagation speed by executing the predetermined reflected sound velocity calculation from the reflected wave arrival time determining means to determine the wave arrival time and the calculated reflected wave arrival times corresponding to different probe intervals. And means.

In the ultrasonic nondestructive measuring apparatus of the present invention, the received signal waveform intermediate point determining means has an amplitude of 0 between the point where the amplitude of the received signal waveform is maximum and the second largest point. A point is calculated as the intermediate point.

Further, in the ultrasonic nondestructive measurement apparatus of the present invention, the frequency analysis hand stage, when the noise in the received signal waveform is judged to be superimposed, by changing the installation distance and the installation position of the probe And means for generating a command to re-measure.

  Further, in the ultrasonic nondestructive measuring apparatus of the present invention, in order to change the installation distance and the installation position of the probe, the installation positions of the transmission probe and the reception probe are changed in the concrete structure. The apparatus further comprises means for changing the measurement point at an axis at a predetermined rotational speed.

Further, in the ultrasonic nondestructive measurement apparatus of the present invention, the transmitting probe and the receiving probe is configured installation distance and the installation position from the plurality of sets of different respectively, automatically switching the plurality of sets again It further comprises a measurement position switching signal generating means for generating a measurement position switching signal for measurement.

Furthermore, the ultrasonic nondestructive measurement method of the present invention uses a transmitting probe and a receiving probe arranged at a predetermined interval on the surface of a concrete structure to measure the ultrasonic propagation velocity of the concrete structure by a reflected wave method. An ultrasonic nondestructive measurement method for measuring, comprising: (a) controlling to generate ultrasonic waves from the transmitting probe; and (b) from the receiving probe on the bottom surface of the concrete structure. A step of controlling the reflected received signal to be acquired as a received signal waveform starting from the generation time of the ultrasonic wave; and (c) performing frequency analysis on the received signal waveform to determine whether the signal is a single frequency signal. and determining whether the received signal noise is superimposed or discriminated by a from; (d) the received signal waveform, absent step to calculate the midpoint of the received signal waveform based on the amplitude of the received signal waveform When, regular reflected wave arrives at the single frequency and the concrete structure of the reflection time calculated from the midpoint of e) receiving a signal waveform the thus noise to step (c) is determined not to be overlapped And (f) executing a predetermined reflected sound velocity calculation from the calculated reflected wave arrival times corresponding to different probe intervals, and determining an ultrasonic wave propagation velocity. Features.

Further, in the ultrasonic nondestructive measuring method of the present invention, the step (d) is the point at which the amplitude of the amplitude of the received signal waveform exists between the points large points and the second as the maximum becomes 0 It is calculated as an intermediate point.

In the ultrasonic nondestructive measurement method of the present invention, the step (c ) may change the installation distance and the installation position of the probe when it is determined that noise is superimposed on the received signal waveform. And generating a command to remeasure.

  In the ultrasonic nondestructive measurement method of the present invention, in order to change the installation distance and the installation position of the probe, the installation positions of the transmission probe and the reception probe are changed in the concrete structure. The method further includes the step of changing the measurement point at an axis at a predetermined rotational speed.

Further, the present invention provides an ultrasonic nondestructive measurement in which the ultrasonic wave propagation speed of a concrete structure is measured by a reflected wave method using a transmission probe and a reception probe arranged at predetermined intervals on the surface of the concrete structure. A computer configured as an apparatus; (a) controlling to generate ultrasonic waves from the transmission probe; and (b) receiving signals reflected on the bottom surface of the concrete structure from the reception probe. A step of performing control so as to obtain a reception signal waveform starting from the generation time of the ultrasonic wave, and (c) performing frequency analysis on the reception signal waveform to determine whether the signal is a single frequency signal. and determining whether the received signal noise is superimposed, and Luz step to calculate the midpoint of (d) from the received signal waveform, the received signal waveform based on the amplitude of the received signal waveform, ( ) Said single frequency and regular reflection time in the concrete structure the reflection time calculated from the midpoint of the received signal waveform the thus noise to step (c) is determined not to be overlapped And (f) executing a predetermined reflected sound velocity calculation from the calculated reflected wave arrival times corresponding to different probe intervals, and determining an ultrasonic wave propagation velocity. It can also be configured as a program.

  Even if there is no basic information (thickness information of the concrete structure) according to the present invention, the normal ultrasonic propagation time can be increased with high accuracy without causing the need to core a part of the concrete structure. Because it is possible to measure, it is possible to measure the ultrasonic propagation velocity inside the concrete non-destructively in the underground structure. This allows crack depth, internal crack depth, concrete structure thickness, concrete structure. It becomes possible to estimate the compressive strength of an object with high accuracy.

It is the schematic which applies the ultrasonic nondestructive measuring device of one Example by this invention. It is the schematic of the ultrasonic nondestructive measuring device of one Example by this invention. It is a block diagram which shows the detail of the received signal waveform analysis part in the ultrasonic nondestructive measuring device of one Example by this invention. It is a flowchart which shows operation | movement of the ultrasonic nondestructive measuring apparatus of one Example by this invention. (A) includes a transmission probe and a reception probe arranged at a probe interval La on a surface of a concrete structure, and a transmission probe and a reception probe arranged at a probe interval Lb. It is the top view written together, (b) is the front view. (A), (b) is the distance between the probes La and Lb, respectively, by a non-destructive measuring apparatus according to an embodiment of the present invention for a concrete structure having a predetermined thickness provided on a natural ground. It is explanatory drawing which calculates | requires the reflected wave arrival time Ta and Tb, and calculates | requires the value of reflected sound velocity V. FIG. (A), (b) are the probe intervals La, Lb for a concrete structure 1 having a predetermined thickness H provided on a natural ground by an ultrasonic nondestructive measuring apparatus according to an embodiment of the present invention. FIG. 6 is an explanatory diagram of received signal waveform examples Fa (t) and Fb (t) respectively corresponding to reflected wave arrival times Ta and Tb that are finally determined. With the ultrasonic nondestructive measuring apparatus according to one embodiment of the present invention, the reflected wave arrival times Ta and Tb corresponding to the probe intervals La and Lb are calculated with reference to the ultrasonic reflection point O, and the value of the reflected sound velocity V is calculated. It is explanatory drawing which calculates | requires. (A) shows an example in the case where the ultrasonic nondestructive measuring apparatus according to one embodiment of the present invention determines that the received signal waveform is a single frequency signal, and (b) shows one embodiment according to the present invention. It is a figure which shows the example in the case of determining with an example ultrasonic nondestructive measuring device that a received signal waveform is not a signal of a single frequency. (A), (b) is a figure which shows an example of the received signal waveform in the determination process of reflected wave arrival time by the ultrasonic nondestructive measuring device of one Example by this invention. A probe that fixes a plurality of sets of transmission probes and reception probes at different predetermined intervals in order to automatically change the installation distances of the probe intervals La and Lb by the ultrasonic nondestructive measuring apparatus according to the second embodiment. It is explanatory drawing of the measurement assistance apparatus which consists of a fixing device and a probe switch. In order to automatically change the installation distances and installation positions of the probe intervals La and Lb by the ultrasonic nondestructive measuring apparatus according to the third embodiment, a plurality of sets of transmission probes and reception probes are fixed at different predetermined intervals. It is explanatory drawing of the measurement auxiliary | assistance apparatus which consists of a probe fixing device, a probe switch, and the rotation mechanism which rotates a probe fixing device by making the center of the probe space | interval fixed at a predetermined interval into a rotating shaft. A plurality of sets of transmission probes and reception probes having probe intervals La and Lb constituting the respective sets are fixed to the installation distance and the installation position that can be changed in advance by the ultrasonic nondestructive measuring apparatus according to the fourth embodiment. It is explanatory drawing of a measurement auxiliary | assistance apparatus provided with the probe fixing device to perform. (A) is a schematic diagram of a transmission probe, and (b) is a schematic diagram of a reception probe. (A) is explanatory drawing of the measurement technique by the transmission method using a transmission probe and a reception probe, (b) is the measurement technique by the surface method using a transmission probe and a reception probe. It is explanatory drawing of. It is a figure which shows the relationship between the sound velocity (ultrasonic propagation velocity) of the ultrasonic wave in concrete, and the compressive strength of a concrete structure. (A), (b) It is a figure which shows the example which measures the reflected wave arrival time in the concrete structure of measurement object accidentally.

  First, the ultrasonic nondestructive measuring apparatus according to the first embodiment of the present invention will be described. The ultrasonic nondestructive measuring method and program according to the present invention will become clear from the description of the ultrasonic nondestructive measuring apparatus according to the first embodiment of the present invention.

〔Device configuration〕
FIG. 1 is a schematic diagram to which an ultrasonic nondestructive measuring apparatus according to an embodiment of the present invention is applied. The ultrasonic nondestructive measuring device 6 of the present embodiment is a device that measures the ultrasonic propagation velocity of a concrete structure by a reflected wave method. The transmitting probe 4 and the receiving probe 5 are placed on the surface of the concrete structure 1. Are arranged at predetermined intervals, and the reception probe 5 detects the component reflected by the bottom surface of the concrete structure 1 from the transmission probe 4 and the ultrasonic wave 9 from the surface to the bottom surface of the concrete structure 1 as a reception signal. The probe installation distance and installation position are made variable to detect a reception signal without noise, and the propagation time of the ultrasonic wave 9 in the concrete structure 1 is measured from the voltage waveform of the reception signal to determine the ultrasonic wave propagation speed. The calculated propagation velocity is displayed on the display device 7. In the first embodiment, every time a received signal waveform in a probe at a predetermined interval is measured, the received signal waveform is displayed on the display device 7 to determine whether or not the measured signal includes noise, and the received signal waveform includes noise. In this case, the reception signal waveform of the probe at a predetermined interval can be installed at a different installation position. However, in the following explanation, it is determined whether or not the reception signal waveform contains noise. A case in which the ultrasonic nondestructive measuring device 6 automatically performs will be described.

  As shown in FIG. 1, when calculating the propagation velocity of the concrete structure 1 using the transmission probe 4 and the reception probe 5 shown in FIG. An example in which the concrete structure 1 is provided will be described. Unlike the prior art, the ultrasonic nondestructive measuring apparatus 6 of the present embodiment performs waveform analysis by changing the installation distance and installation position of the probe, and reflects the reflected wave from the bottom surface of the concrete structure 1. The reflected wave arrival time is calculated so as to minimize the measurement error, and the ultrasonic wave propagation speed inside the concrete structure 1 is determined. Details will be described below.

  FIG. 2 is a schematic diagram of an ultrasonic nondestructive measuring apparatus according to an embodiment of the present invention. The ultrasonic nondestructive measuring device 6 includes a user interface 61, a control unit 62, a storage unit 63, a control signal generation unit 64, a reception signal processing unit 65, a display control unit 66, and a measurement position switching signal generation unit. 67. The control unit 62 includes a control signal start setting unit 621, a reception signal waveform recording unit 622, a typical FFT calculation unit 623 as a spectrum calculation, and a reception signal waveform analysis unit 624. Note that these functions particularly indicate functions different from the conventional ones, and are not intended to exclude other functions. The ultrasonic nondestructive measuring apparatus 6 can be preferably configured by a computer, and the user interface 61 can be configured by an arbitrary man-machine interface for inputting measurement parameters. In order to realize each function by the central processing unit (CPU), a program to be executed by the CPU can be stored in a predetermined area of the storage unit 63. In addition, data required for realizing each function can be temporarily or permanently stored in the storage unit 63. Such a storage unit 63 can be appropriately configured by a ROM, RAM, hard disk, or the like inside the computer, or can be configured by using an external storage device (for example, an external hard disk).

  The control signal generation unit 64 has a function of giving a control signal of a voltage according to a command from the control signal start setting unit 621 to the transmission probe 4.

  The reception signal processing unit 65 obtains an ultrasonic reception signal reflected in the concrete structure 1 via the reception probe 5-1, and starts from the time when the control signal generation unit 64 generates the control signal ( It has a function of processing the received signal waveform starting from the generation time of the ultrasonic wave and sending it to the received signal waveform recording unit 622.

  The display controller 66 has a function of displaying the analysis result of the received signal waveform analyzer 624 on the display device 7.

  The measurement position switching signal generation unit 67 has a function of generating a measurement position switching signal outside to change the installation distance and the installation position of the probe intervals La and Lb according to the analysis result of the received signal waveform analysis unit 624. (Detailed in Example 2 to Example 4).

  The control signal start setting unit 621 has a function of giving a command to the control signal generation unit 64 so as to emit ultrasonic waves from the transmission probe 4-1 with a predetermined voltage.

  The reception signal waveform recording unit 622 has a function of recording a reception signal waveform starting from the time when the control signal is issued from the reception signal processing unit 65.

  The FFT operation unit 623 functions to perform a Fourier transform process on the recorded received signal waveform, and send a received signal waveform corresponding to the waveform data subjected to the Fourier transform process to the received signal waveform analyzing unit 624.

  The reception signal waveform analysis unit 624 performs frequency analysis to determine whether or not the signal is a single frequency signal from the waveform data subjected to the Fourier transform processing obtained from the FFT operation unit 623, and the reception signal waveform has a single frequency. When the signal is determined to be a signal, the reflected wave arrival time is determined by determining the intermediate point of the received signal waveform based on the amplitude of the received signal waveform from the received signal waveform corresponding to the value fp of the single frequency. It has a function of calculating and determining the ultrasonic wave propagation speed (reflection sound speed) from the reflected wave arrival time obtained at the interval between the tentacles. When the received signal waveform analysis unit 624 determines that the received signal waveform is not a single frequency signal (noise is superimposed), the measurement is performed again by changing the installation distance and installation position of the probe. It functions to generate a command, display a measurement error on the display device 7 via the display control unit 66, and notify the measurer.

  Details of the received signal waveform analysis unit 624 are shown in FIG. The reception signal waveform analysis unit 624 includes a dominant frequency determination unit 6241, a reception signal waveform intermediate point determination unit 6242, a reflected wave arrival time determination unit 6243, and a reflected sound speed calculation unit 6244.

  The dominant frequency determination unit 6241 has a function of performing frequency analysis to determine whether or not the signal is a single frequency (predominant frequency fp) from the waveform data subjected to the Fourier transform processing obtained from the FFT operation unit 623.

  The reception signal waveform intermediate point determination unit 6242 calculates the maximum waveform peak time Pn (the maximum peak time is P1 and the second largest peak time is P2) in the reception signal waveform from the reception signal waveform recorded in the reception signal waveform recording unit 622. It has a function of detecting and calculating a time T0 (intermediate point) when the acoustic amplitude value between P1 and P2 is zero.

  The reflected wave arrival time determination unit 6243 subtracts the 1 / fp half-wavelength that is superior from the intermediate point determined by the received signal waveform intermediate point determination unit 6242 based on the dominant frequency fp determined by the dominant frequency determination unit 6241. The reflected wave arrival time is calculated.

  The reflected sound speed calculation unit 6244 calculates the reflected sound speed (ultrasonic propagation speed) V by executing the reflected sound speed calculation based on Equation (3) to be described later from the corresponding reflected wave arrival time calculated for different probe intervals. It has the function to do.

  Hereinafter, the operation of the ultrasonic nondestructive measuring apparatus 6 of this embodiment will be described with reference to FIG.

  In step S <b> 1, as a measurement preparation, the measurer sets a measurement parameter in the ultrasonic nondestructive measurement apparatus 6 through the user interface 61. The measurement parameters are the probe interval (La, Lb, etc.) between the transmission probe 4 and the reception probe 5, and the voltage applied to the transmission probe 4, and are set before starting the measurement. In the following description, after the ultrasonic propagation time Ta is measured at the probe interval La between the transmission probe 4 and the reception probe 5, the probe installation position is made variable as necessary. An example in which the ultrasonic propagation time Tb is measured at the probe interval Lb between the transmission probe 4 and the reception probe 5 (the installation position of the probe is made variable as necessary) will be described. Therefore, the transmission probe 4 and the reception probe 5 arranged at the probe interval La are represented by the transmission probe 4-1 and the reception probe 5-1, respectively, and arranged at the probe interval Lb. The transmission probe 4 and the reception probe 5 are represented by a transmission probe 4-2 and a reception probe 5-2, respectively. In an actual implementation example, La = 60 mm and Lb = 120 mm.

  When the probe is installed, energy loss between the transducer in the transmission probe 4-1 and the reception probe 5-1 and the surface of the concrete structure 1 tends to increase. It is preferable that grease or the like is applied between the ceramic structure 1 and the concrete structure 1 to expel air intervening on the contact surface so that the vibrator is in close contact with the surface of the concrete structure 1. Further, when the target concrete structure 1 is a reinforced concrete structure, the presence or absence of the influence of the reinforcing bars may be determined from a statistical viewpoint after measuring a plurality of locations according to the method of the present invention. It is preferable to install the probe after measuring the position by the electromagnetic wave radar method, the electromagnetic induction method or the like and determining in advance a point that is not affected by the reinforcing bar as much as possible. Moreover, when there are large irregularities on the surface of the concrete structure 1, it is necessary to smooth the surface by polishing or the like.

  In steps S2 and S3, the ultrasonic nondestructive measuring device 6 measures the ultrasonic propagation time Ta at the probe interval La between the transmission probe 4-1 and the reception probe 5-1. More specifically, the transmission probe 4-1 and the reception probe 5-1 are installed at the inter-probe interval La, and the transmission probe 4-1 is set at a predetermined voltage by the control signal start setting unit 621. The control signal generator 64 gives a command to the control signal generator 64 to emit ultrasonic waves, and the control signal generator 64 gives a control signal of a voltage corresponding to the command from the control signal generator 64 to the transmission probe 4-1. On the other hand, the reception signal processing unit 65 obtains the reception signal of the ultrasonic wave reflected in the concrete structure 1 via the reception probe 5-1, and the time when the control signal generation unit 64 issues the control signal ( The received signal waveform is processed starting from the time when generation of the ultrasonic wave is zero) and sent to the received signal waveform recording unit 622. The reception signal waveform recording unit 622 records a reception signal waveform starting from the time when the control signal is generated from the reception signal processing unit 65 (the time when the generation of ultrasonic waves is started is zero).

  Next, the ultrasonic nondestructive measuring apparatus 6 reads out the received signal waveform recorded in the received signal waveform recording unit 622 by the FFT operation unit 623, performs a Fourier transform process on the received signal waveform, and performs the Fourier transform process. The received signal waveform corresponding to the waveform data is sent to the received signal waveform analyzing unit 624.

  The reception signal waveform analysis unit 624 performs frequency analysis to determine whether or not the signal is a single frequency signal from the waveform data subjected to the Fourier transform processing obtained from the FFT operation unit 623, and the reception signal waveform has a single frequency. When it is determined that the signal is a signal, the reflected wave arrival time determination Ta is determined by determining an intermediate point of the received signal waveform based on the amplitude of the received signal waveform from the received signal waveform corresponding to the single frequency value fp. . On the other hand, if the received signal waveform analysis unit 624 determines that the received signal waveform is not a single-frequency signal (noise is superimposed), the display device 7 indicates a measurement error via the display control unit 66. To display to the measurer. When the measurer knows that the measurement error has occurred, each probe is detected at the probe interval La between the transmission probe 4-1 and the reception probe 5-1 until the received signal waveform becomes a single frequency value fp. The ultrasonic wave propagation time Ta is measured at the probe interval La between the transmission probe 4-1 and the reception probe 5-1 by changing the installation position of the probe. Even if the installation position of each probe is changed by 360 degrees with the probe interval La between the transmission probe 4 and the reception probe 5, the result that the reception signal waveform becomes a single frequency value fp is obtained. If not, change the measurement point.

  FIGS. 9A and 9B are diagrams illustrating an operation example of frequency analysis by the reception signal waveform analysis unit 624. FIG. FIG. 9A shows an example in which the received signal waveform is determined by the received signal waveform analysis unit 624 to be a single frequency signal. Since no noise is superimposed, the received signal waveform is controlled. It is obtained as a simple reflected waveform after the ultrasonic wave propagation time Ta starting from the time when the signal is emitted, and a single frequency value fp can be obtained by performing frequency analysis by Fourier transform. On the other hand, FIG. 9B is an example in the case where the received signal waveform analysis unit 624 determines that the received signal waveform is not a single frequency signal, and is a case where noise is superimposed. It is obtained as a reflected waveform in which noise is superimposed on the ultrasonic propagation time Ta ′ starting from the time when the control signal is issued. When frequency analysis by Fourier transform is executed, a single frequency value fp cannot be obtained, and the noise component A result including one or more of (fn) is obtained. That is, a simple reflected wave spectrum in which only the reflected wave from the thickness of the concrete structure is measured without noise superimposition is aggregated in a certain frequency band, but it is a rough spectrum with a large amount of noise superimposed. As for the reflected wave spectrum, it can be seen that it is distributed over a wide frequency band. Therefore, the signal component of the received signal waveform that is assumed not to be affected by the aggregate or the like can be identified by obtaining the single frequency value fp by the frequency analysis of the received signal waveform analysis unit 624. Become.

  Subsequently, referring to FIGS. 5A and 5B, the probe interval La between the transmission probe 4 and the reception probe 5 is changed until the reception signal waveform becomes a single frequency value fp. An example of changing the installation position of the probe will be described. FIG. 5A shows a transmission probe 4-1 and a reception probe 5-1 arranged at the probe interval La on the surface of the concrete structure 1, and a transmission probe arranged at the probe interval Lb. It is a top view in which the transducer 4-2 and the reception probe 5-2 are written together, and the lines (measurement line 1 and measurement line 2) to be measured when changing the installation positions of the respective probes are indicated by broken lines. ing. FIG. 5B shows a transmission probe 4-1 and a reception probe 5-1 arranged at the probe interval La on the surface of the concrete structure 1, and a transmission probe arranged at the probe interval Lb. It is the front view which wrote together the touch element 4-2 and the receiving probe 5-2. The ultrasonic reflection point is on the bottom surface of the concrete structure 1, and referring to FIG. 5B, if there is no reflection factor such as aggregate on the ultrasonic propagation path, the received signal waveform is received by the FFT calculation unit 623. Can be determined to be single frequency signals. On the other hand, when there is a reflection factor such as aggregate on the ultrasonic wave propagation path, the received signal waveform analysis unit 624 can determine that the received signal waveform is not a single-frequency signal. As shown in FIG. 5, the installation positions of the probes are changed along the survey line 1 at the probe interval La between the transmission probe 4-1 and the reception probe 5-1 along the survey line 1. In the measurement, the received signal waveform can be acquired almost in real time to know whether the received signal waveform is a single frequency signal. Therefore, the measurement is performed at a constant speed in the circumferential direction around the ultrasonic reflection point. It is preferable to search the installation position of the probe where the received signal waveform becomes a single frequency signal while moving, and as soon as the installation position of the probe where the received signal waveform becomes a single frequency signal is found, The process proceeds to the process of determining the reflected wave arrival time.

  The reflected wave arrival time determination process will be described with reference to FIG. FIGS. 10A and 10B are diagrams illustrating an example of a received signal waveform in the reflected wave arrival time determination process. In determining the reflected wave arrival time Ta in the transmission probe 4-1 and the reception probe 5-1 arranged at the probe interval La, the ultrasonic nondestructive measuring device 6 first receives the received signal waveform intermediate point. The maximum waveform peak time Pn (maximum peak) in the received signal waveform is selected by the determination unit 6242 so as to select an intermediate point that minimizes the measurement error from the reflected waves (1 to 1.5 waves) from the bottom surface of the concrete structure 1. The time T0 (intermediate point) when the acoustic amplitude value between P1 and P2 is 0 is calculated by detecting the time P1 and the second largest peak time P2). Subsequently, the reflected wave arrival time determination unit 6243 subtracts a half wavelength of 1 / fp that is dominant from the midpoint based on the dominant frequency fp determined by the dominant frequency determination unit 6241 as shown in Expression (1). The reflected wave arrival time Ta is automatically calculated.

  The reflected wave from the bottom surface of the concrete structure 1 is a set of waves (1 to 1.5 waves) having the largest acoustic amplitude (sound pressure). The maximum amplitude point P1 is given as a time when the acoustic amplitude is maximum. The second largest amplitude point P2 is given as the time when the acoustic amplitude is the second largest. The intermediate point T0 is given as a time when the acoustic amplitude becomes 0 between the maximum amplitude point and the second largest amplitude point in the concrete reflected wave. The reflected wave arrival time is given as the time when the reflected wave on the bottom surface of the concrete is received. In the case of the probe interval La, the reflected wave arrival time Ta is obtained from the intermediate point T0a and the dominant frequency fp as shown in Expression (1).

  Here, Ta is the reflected wave arrival time at the probe interval La, T0a is the midpoint of the received signal waveform at the probe interval La, and fp is the dominant frequency.

  When the received signal waveform intermediate point determination unit 6242 cannot detect the maximum waveform peak time Pn (the maximum peak time is P1 and the second largest peak time is P2) in the received signal waveform due to the presence of noise. The reception signal waveform intermediate point determination unit 6242 functions to display a measurement error message on the display device 7 via the display control unit 66 and notify the measurement person. Also in this case, as shown in FIG. 5A, the installation positions of the probes are set along the survey line 1 at the probe interval La between the transmission probe 4-1 and the reception probe 5-1. change.

  In measurement, since the received signal waveform can be obtained almost in real time to know whether or not the received signal waveform includes noise, as shown in FIG. It is also possible to search for the installation position of the probe in which the received signal waveform becomes a signal that does not contain noise while moving at a constant speed in the circumferential direction. Further, when determining the dominant frequency fp and the received signal waveform capable of detecting the maximum waveform peak time Pn (the maximum peak time is P1, the second largest peak time is P2), each search associated with these determinations is performed. Since the installation positions of the transducers do not have to coincide with each other, the dominant frequency fp can be determined after the reception signal waveform is determined, that is, the probe installation positions are individually searched. Can do. In addition, in order to determine the received signal waveform and the dominant frequency fp at the same time, the reflected waveform was recorded after the probe was fixed and moved on the arc around the midpoint between the probes. It can also be configured to determine whether the reflected wave arrival time is determined by determining whether noise is superimposed on the received signal waveform. For example, while rotating and scanning the probe (while changing the ultrasonic traveling direction), the received signal waveform is recorded, and the probe is rotated and scanned to determine whether noise is superimposed on the recorded received signal waveform. However, if it is determined that noise is superimposed, it is possible to perform measurement with excellent real-time performance by changing the probe interval or measurement location and performing the same operation. .

  Also, in the actual implementation example, when recording the reflected waveform while moving it on the arc around the midpoint between the probes, it is necessary to determine in advance a place where the influence of the reinforcing bar is not affected as much as possible. This is suitable for searching for an installation position by rotational scanning of the touch element. In the implementation example, the rotational scanning speed of the probe is set to about 6 mm / sec.

  In steps S4 and S5, the ultrasonic nondestructive measuring device 6 measures the ultrasonic propagation time Tb at the probe interval Lb in the same manner as the measurement of the ultrasonic propagation time Ta. Also in this case, as shown in FIG. 5A, the installation positions of the probes are determined along the survey line 2 at the probe interval Lb between the transmission probe 4-2 and the reception probe 5-2. Can be changed. The reflected wave arrival time Tb is obtained from Equation (2). When the measurement target is the same, it is not always necessary to measure the dominant frequency fp again. However, for the convenience of signal processing, the determination of the dominant frequency fp and the maximum waveform peak time Pn (the maximum peak time is P1, the second is the second). When the determination of the received signal waveform capable of detecting the large peak time P2) is executed as a series of processes, the dominant frequency fp can be set as an average value of the respective measurement results.

  Here, Tb: reflected wave arrival time at the probe interval Lb, T0b: intermediate point at the probe interval Lb, and fp: dominant frequency.

  In step S6, the ultrasonic nondestructive measuring apparatus 6 uses the reflected sound speed calculation unit 6244 to calculate the reflected wave arrival times Ta and Tb corresponding to the probe intervals La and Lb, respectively, based on Equation (3) described later. The reflected sound velocity calculation is executed to automatically calculate the reflected sound velocity (ultrasonic propagation velocity) V. In step S7, the ultrasonic nondestructive measuring device 6 displays the calculated reflected sound velocity V under the control of the display control unit 66. Display on device 7.

  The calculation of the reflected sound velocity V will be described in detail with reference to FIGS. 6 (a) and 6 (b) show a concrete structure 1 having a predetermined thickness H provided on the natural ground 2 by an ultrasonic nondestructive measuring device 6 at probe intervals La and Lb, respectively. It is explanatory drawing which calculates | requires the value of the reflected sound speed V from the corresponding calculated reflected wave arrival time Ta and Tb. 7 (a) and 7 (b) show a concrete structure 1 having a predetermined thickness H provided on the natural ground 2 by an ultrasonic nondestructive measuring device 6 at probe intervals La and Lb, respectively. It is explanatory drawing of the corresponding received signal waveform example Fa (t), Fb (t), and finally the reflected wave arrival time Ta, Tb. FIG. 8 is an explanatory diagram for obtaining the value of the reflected sound velocity V from the reflected wave arrival times Ta and Tb calculated respectively corresponding to the probe intervals La and Lb with the ultrasonic reflection point O as a reference.

Referring to FIG.
OP ² = (OC ² ) − (PC ² ) = (OD ² ) − (PD ² )
So,
(V × Ta / 2) ² − (La / 2) ² = (V × Tb / 2) ² − (Lb / 2) ²
By expanding for V, equation (3) is obtained.

  Here, V: reflected sound velocity, La, Lb: spacing between probes, Ta, Tb: reflected wave arrival time.

  Therefore, the calculated probe intervals La and Lb and the values of the reflected wave arrival times Ta and Tb at that time are substituted into the following formula (3) to perform the calculation, thereby propagating in the concrete structure 1. The ultrasonic wave propagation speed (reflection sound speed) can be calculated. Since it can be determined that the reflected sound speed from the thickness H of the concrete structure 1 at the probe interval La, Lb is the same, the ultrasonic wave propagation speed (reflected sound speed) in the concrete structure 1 is highly accurate. Can be obtained.

  In other words, in order to obtain the ultrasonic wave propagation speed (reflection sound speed) with high accuracy based on the expression (3), it depends on the measurement accuracy of the reflected wave arrival times Ta and Tb. Conventional measurement techniques for reflected wave arrival times Ta and Tb may cause variations in measurement multiple times. Noise caused by “structure dependency of measurement target structure” and “concrete material dependency of concrete structure” As a result, the reflected wave arrival times Ta and Tb can be accurately measured according to the ultrasonic nondestructive measuring apparatus 6 of the first embodiment of the present invention.

  As a result, even in underground structures such as tunnels and manholes, it is possible to measure the ultrasonic sound velocity that represents the internal properties of the concrete without destruction.

  Moreover, it is possible to estimate the crack depth, internal crack depth, concrete structure thickness, and compressive strength in a non-destructive manner using the ultrasonic velocity measured accurately.

  By estimating the compressive strength, it is possible to evaluate the soundness of the concrete structure nondestructively.

  In the first embodiment described above, when noise is confirmed by the measurer, the installation distance and the installation position of the probe intervals La and Lb are made variable, and the received signal waveform and its frequency distribution are respectively displayed on the display device 7. The example which implements many times of measurement, confirming by comparison was demonstrated. According to the first embodiment, the frequency range of the reflected wave from the thickness H of the concrete structure 1 which is a fixed point is present in a certain region by comparing and confirming each received signal waveform recorded. If it is confirmed by frequency analysis that the frequency distribution covers a wide area, it can be determined that the reflected wave spectrum contains a lot of noise and is used. It can also be determined that the data is not appropriate. Then, the reflected wave spectrum in which the frequency distribution is converged in a certain range can be determined as data having a low influence of noise.

  As described above, it is possible to identify the amount of noise by performing the frequency analysis shown in FIG. 9, but there are non-uniform ultrasonic scattering sources such as aggregate, gravel and bubbles in the concrete material. It is also true that it is difficult to completely eliminate individual differences. Therefore, not only the frequency analysis but also the acoustic amplitude existing between the point where the amplitude of the reflected wave from the bottom surface of the concrete structure 1 is the maximum and the point where the acoustic amplitude is the second largest as shown in FIG. By calculating the intermediate point, it is possible to further reduce variations in the arrival time of the reflected wave due to the influence of ultrasonic scattering reduction of aggregates, gravel, bubbles, etc. in the concrete material. Moreover, since it is known that the reflected wave with high accuracy is about 1 to 1.5 waves, the reflected wave arrival time can be obtained simply by subtracting the half wavelength of the wavelength 1 / fp which is excellent from the above-mentioned intermediate point. Can be calculated with high accuracy.

  In addition, by applying the “superimposed wave filtering process” for obtaining the intersection coordinate time from the smoothness of the peak time position of the ultrasonic reception signal in the technique of Patent Document 1 to the analysis of the reception signal waveform by the reception signal waveform analysis unit 624, Further, noise can be reduced, and the reflected wave arrival time can be calculated with higher accuracy.

  The ultrasonic nondestructive measuring device 6 of the present embodiment can measure the reflected wave sound velocity almost the same as the transmitted sound velocity, increasing the compressive strength, crack depth, internal crack depth, and concrete structure thickness. It is possible to estimate with accuracy.

  In addition, the ultrasonic nondestructive measuring device 6 of this embodiment estimates the crack depth, the internal crack depth, the thickness of the concrete structure, and the compressive strength in a nondestructive manner using the ultrasonic velocity measured accurately. It is possible.

  Moreover, it is possible to evaluate the soundness of a concrete structure nondestructively by estimating compressive strength with the ultrasonic nondestructive measuring apparatus 6 of a present Example.

  In the first embodiment described above, when noise is confirmed by the measurer, the installation distance and the installation position of the probe intervals La and Lb are made variable, and the received signal waveform and its frequency distribution are respectively displayed on the display device 7. The example which implements many times of measurement, confirming by comparison was demonstrated. In the following embodiments, a configuration example in which the installation distances and the installation positions of the probe intervals La and Lb are automatically variable will be described.

  Hereinafter, application examples of the ultrasonic nondestructive measuring apparatus according to the second embodiment of the present invention will be described. FIG. 11 shows a plurality of sets of transmission probes and reception probes fixed at different predetermined intervals in order to automatically change the installation distances of the probe intervals La and Lb by the ultrasonic nondestructive measuring apparatus according to the second embodiment. It is explanatory drawing of the measurement auxiliary | assistance apparatus which consists of the probe fixing device 14 and the probe switchers 12 and 13 which switch a probe. The ultrasonic nondestructive measuring apparatus 6 of the second embodiment is the same as that shown in FIG. 2, but the installation distances of the probe intervals La and Lb are automatically changed using the measurement position switching signal from the measurement position switching signal generator 67. It is different in the point to do.

  The measurement auxiliary device shown in FIG. 11 is illustratively composed of three sets of a transmission probe 4-1 and a reception probe 5-1, a transmission probe 4-2 and a reception probe 5-2, and A probe fixture 14 for fixing the transmission probe 4-3 and the reception probe 5-3 at different predetermined intervals (for example, 60 mm, 120 mm, and 180 mm, respectively) is provided. Is shown as an example in which switching is performed by a measurement position switching signal from the ultrasonic nondestructive measuring device 6.

  In the first embodiment, an example is described in which, when obtaining a received signal waveform at each of the probe intervals La and Lb, when the received signal waveform includes noise, the interval is changed by the measurer. In FIG. 2, since the measurement assisting device shown in FIG. 11 is provided, it is possible to automatically obtain the received signal waveform at each of the probe intervals La and Lb. This has the advantage that when measuring the arrival times of the plurality of reflected waves, there is no deviation of measurement points.

  Therefore, the reception signal waveform analysis unit 624 in the ultrasonic nondestructive measurement apparatus 6 according to the second embodiment obtains the reception signal waveform at each of the two probe intervals, and the transmission probe 4-1 and the reception probe. Measurement is started from any one of the child 5-1, the transmission probe 4-2 and the reception probe 5-2, and the transmission probe 4-3 and the reception probe 5-3. When the reflected wave arrival time can be calculated, the transmission probe 4-1, the reception probe 5-1, the transmission probe 4-2, and the reception are different from the set of the calculated reflected wave arrival times. In order to start measurement by any one of the probe 5-2, the transmission probe 4-3, and the reception probe 5-3, the measurement position switching signal is sent via the measurement position switching signal generation unit 67. This is sent to the probe changers 12 and 13. The probe changers 12 and 13 are a transmission probe 4-1, a reception probe 5-1, a transmission probe 4-2, a reception probe 5-2, and a transmission probe 4-3. In addition, since any one of the reception probes 5-3 is switched without requiring the operator to change the arrangement, reception signal waveforms with different probe intervals can be automatically obtained.

  Note that the measurement assisting device shown in FIG. 11 exemplarily shows a transmission probe and a reception probe consisting of three groups, but this is only one set of the transmission probe and the reception probe. This is for the purpose of exemplifying such that even when noise such that the desired arrival time of the reflected wave cannot be calculated from the probe is included, it can be switched automatically. Therefore, in the second embodiment, the probe fixture 14 may fix two sets of transmission probes and reception probes, or fix four sets or more of transmission probes and reception probes. You may do it. Furthermore, as long as the measurement points are the same, the installation positions of the transmission probes and the reception probes of each set need not be on the same axis.

  Next, a configuration example in which the installation distance and the installation position of the probe intervals La and Lb are automatically changed from the application example of the second embodiment described above will be described.

  Hereinafter, application examples of the ultrasonic nondestructive measuring apparatus according to the third embodiment of the present invention will be described. FIG. 12 shows a plurality of sets of transmission probes and reception probes that are different from each other in order to automatically change the installation distances and installation positions of the probe intervals La and Lb by the ultrasonic nondestructive measuring apparatus according to the third embodiment. A probe fixing device 14 that is fixed at intervals, probe switchers 12 and 13, and a rotation mechanism that rotates the probe fixing device 14 with the center of the probe interval fixed at predetermined intervals as a rotation axis 21 (for example, , Motor) is an explanatory view of a measurement auxiliary device. The ultrasonic nondestructive measuring apparatus 6 according to the third embodiment is the same as that shown in FIG. 2, but using the measurement position switching signal from the measurement position switching signal generator 67, the installation distances and the installation positions of the probe intervals La and Lb. Is different in that it is automatically changed. It is preferable to replenish grease or the like between the transmitting probe and the receiving probe and the concrete structure 1 every time it rotates. The probe fixture 14 can be formed of any material such as metal or acrylic.

  Therefore, the reception signal waveform analysis unit 624 in the ultrasonic nondestructive measuring apparatus 6 of the third embodiment obtains the reception signal waveform at each of the two probe intervals, and the transmission probe 4-1 and the reception probe. Measurement is started from any one of the child 5-1, the transmission probe 4-2 and the reception probe 5-2, and the transmission probe 4-3 and the reception probe 5-3. In calculating the reflected wave arrival time, a measurement position switching signal is sent to the rotation mechanism 20 via the measurement position switching signal generator 67 so as to automatically perform the rotation operation described in FIG. Thereby, since the shift | offset | difference of a measurement point can be suppressed completely, the received signal waveform of a different probe space | interval can be obtained automatically with higher precision. Therefore, the received signal waveform analysis unit 624 in the ultrasonic nondestructive measuring apparatus 6 according to the third embodiment, together with the rotating mechanism 20, changes the transmission probe 4 and the reception in order to change the ultrasonic traveling direction in the concrete structure 1. The installation position of the probe 5 is configured as means for changing the measurement point in the concrete structure 1 with a predetermined rotational speed as an axis.

  Next, another configuration example in which the installation distances and the installation positions of the probe intervals La and Lb are automatically changed from the application example of the third embodiment described above will be described.

  Hereinafter, application examples of the ultrasonic nondestructive measuring apparatus according to the fourth embodiment of the present invention will be described. FIG. 13 shows a plurality of sets of transmission probes and reception probes of probe intervals La and Lb constituting each set at the installation distance and the installation position that can be varied in advance by the ultrasonic nondestructive measuring apparatus according to the fourth embodiment. It is explanatory drawing of a measurement assistance apparatus provided with the probe fixing device which fixes a probe. The ultrasonic nondestructive measuring apparatus 6 of the fourth embodiment is the same as that of FIG. 2, but in the third embodiment, the rotation mechanism 20 is used, whereas in the fourth embodiment, the measurement position switching signal generating unit 67 is used. When the installation distance and the installation position of the probe intervals La and Lb are automatically changed using the measurement position switching signal from the probe, the probe interval La constituting each set is set to the installation distance and the installation position that are variable in advance. , Lb, a plurality of sets of transmission probes and reception probes (transmission probe 4-1, reception probe 5-1, through transmission probe 4-6, and reception probe 5-6) are fixed. The difference is that a measurement auxiliary device including the probe fixture 15 is used. Grease or the like may be replenished between the transmitting probe and the receiving probe and the concrete structure 1, and the received signal waveform at each of the two probe intervals can be instantaneously obtained and the measurement point can be obtained. Therefore, the received signal waveforms with different probe intervals can be obtained with higher accuracy and higher speed. In order to improve the accuracy of determining whether or not it is affected by the noise shown in FIG. 17, as shown in FIG. 13, the transmission probe and the reception probe of the third embodiment are used. It is preferable to arrange each of them so as to have an alternating transmission / reception relationship in the circumferential direction. The probe fixture 15 can be formed of any material such as metal or acrylic.

  Although specific embodiments have been described in the above-described embodiments, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the invention. For example, in view of the advantages of the fourth embodiment, each of the transmission probe and the reception probe of the first embodiment may be arranged and measured so as to have an alternating transmission / reception relationship in the circumferential direction. Accordingly, the invention is not limited by the embodiments described above, but only by the claims.

  According to the present invention, since the normal propagation time of ultrasonic waves can be measured with high accuracy for various concrete structures 1, the crack depth, the internal crack depth, and the thickness of the concrete structure are measured. This is useful for estimating the compressive strength of concrete structures with high accuracy.

DESCRIPTION OF SYMBOLS 1 Concrete structure 2 Ground mountain 4,4-1,4-2,4-3,4-4,4-5,4-6 Transmission probe 5,5-1,5-2,5-3 5-4, 5-5, 5-6 Receiving probe 6 Ultrasonic nondestructive measuring device 7 Display device 9 Ultrasonic wave 12, 13 Probe switcher 14, 15 Probe fixing device 20 Rotating mechanism 21 Rotating shaft 41 voltage generator 42 contact medium 51 receiver 52 contact medium 61 user interface 62 control unit 63 storage unit 64 control signal generation unit 65 reception signal processing unit 66 display control unit 67 measurement position switching signal generation unit 621 control signal start setting unit 622 Received signal waveform recording unit 623 FFT calculation unit 624 Received signal waveform analysis unit 6241 Excellent frequency determination unit 6242 Received signal waveform midpoint determination unit 6243 Reflected wave arrival time determination unit 6244 Reflected sound speed calculation unit

Claims (10)

An ultrasonic nondestructive measuring device that measures the ultrasonic propagation velocity of a concrete structure by a reflected wave method with a transmission probe and a reception probe arranged at predetermined intervals on the surface of the concrete structure,
Ultrasonic wave generation means for controlling to generate ultrasonic waves from the transmission probe;
A reception signal processing means for controlling to acquire a reception signal reflected from the bottom surface of the concrete structure from the reception probe as a reception signal waveform starting from the generation time of the ultrasonic wave;
Frequency analysis means for performing frequency analysis on the received signal waveform, determining whether the signal is a single frequency signal, and determining whether the received signal is superimposed with noise;
From the received signal waveform, and the received signal waveform midpoint determining means that to calculate the midpoint of the received signal waveform based on the amplitude of the received signal waveform,
Said single frequency and reflection time calculated from the midpoint of the received signal waveform thus noise on the frequency analysis hand stage is determined not to be superimposed as a regular reflection time in the concrete structure A reflected wave arrival time determining means for determining;
Reflected sound speed calculation means for executing a predetermined reflected sound speed calculation from the calculated reflected wave arrival times corresponding to different probe intervals and determining an ultrasonic propagation speed,
An ultrasonic nondestructive measuring device comprising: The received signal waveform intermediate point determining means calculates, as the intermediate point , a point where the amplitude existing between the point where the amplitude in the received signal waveform is maximum and the second largest point is zero. The ultrasonic nondestructive measuring device according to claim 1. The frequency analysis hand stage, when the noise in the received signal waveform is judged to be superimposed, having means for generating a command to re-measured by changing the installation distance and the installation position of the probe The ultrasonic nondestructive measuring apparatus according to claim 1 or 2, characterized by the above.   Means for changing the installation positions of the transmission probe and the reception probe at a predetermined rotational speed around a measurement point in the concrete structure in order to change the installation distance and the installation position of the probe. The ultrasonic nondestructive measuring device according to claim 3, further comprising: The transmission probe and the reception probe are composed of a plurality of sets having different installation distances and installation positions, and a measurement position for generating a measurement position switching signal for automatically switching and re-measuring the plurality of sets. The ultrasonic nondestructive measuring apparatus according to claim 1, further comprising a switching signal generating unit. An ultrasonic nondestructive measurement method for measuring an ultrasonic propagation velocity of a concrete structure by a reflected wave method with a transmission probe and a reception probe arranged at predetermined intervals on the surface of the concrete structure,
(A) controlling to generate ultrasonic waves from the transmission probe;
(B) controlling to obtain a reception signal reflected from the bottom surface of the concrete structure as a reception signal waveform starting from the generation time of the ultrasonic wave, from the reception probe;
(C) performing frequency analysis on the received signal waveform, determining whether the signal is a single frequency signal, and determining whether the received signal has noise superimposed thereon;
From; (d) received signal waveform, and Luz step to calculate the midpoint of the received signal waveform based on the amplitude of the received signal waveform,
(E) a reflected wave of the normal to said single frequency and reflection time calculated from the midpoint of the received signal waveform the thus noise to step (c) is determined not to be superimposed in the concrete structure A step of determining the arrival time;
(F) performing a predetermined reflected sound velocity calculation from the calculated reflected wave arrival times corresponding to different probe intervals, and determining an ultrasonic propagation velocity;
The ultrasonic nondestructive measuring method characterized by including. The step (d) is characterized in that a point at which an amplitude existing between a point where the amplitude of the received signal waveform is maximum and a second largest point is 0 is calculated as the intermediate point. 6. The ultrasonic nondestructive measurement method according to 6. The step (c ) includes a step of generating a command to change the installation distance and installation position of the probe and perform measurement again when it is determined that noise is superimposed on the received signal waveform. The ultrasonic nondestructive measuring method according to claim 6 or 7, wherein   In order to change the installation distance and the installation position of the probe, the installation position of the transmission probe and the reception probe is changed at a predetermined rotation speed around the measurement point in the concrete structure. The ultrasonic nondestructive measurement method according to claim 8, further comprising: A computer configured as an ultrasonic nondestructive measuring device that measures the ultrasonic wave propagation velocity of a concrete structure by the reflected wave method using a transmitting probe and a receiving probe arranged at predetermined intervals on the surface of the concrete structure. ,
(A) controlling to generate ultrasonic waves from the transmission probe;
(B) controlling to obtain a reception signal reflected from the bottom surface of the concrete structure as a reception signal waveform starting from the generation time of the ultrasonic wave, from the reception probe;
(C) performing frequency analysis on the received signal waveform, determining whether the signal is a single frequency signal, and determining whether the received signal has noise superimposed thereon;
From; (d) received signal waveform, and Luz step to calculate the midpoint of the received signal waveform based on the amplitude of the received signal waveform,
(E) a reflected wave of the normal to said single frequency and reflection time calculated from the midpoint of the received signal waveform the thus noise to step (c) is determined not to be superimposed in the concrete structure A step of determining the arrival time;
(F) performing a predetermined reflected sound velocity calculation from the calculated reflected wave arrival times corresponding to different probe intervals, and determining an ultrasonic propagation velocity;
A program for running

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