JP7478178B2 - Method for estimating the depth position of rebar in reinforced concrete body - Google Patents

Description

The present invention relates to a method for estimating the depth position of rebar in a reinforced concrete body.

A non-destructive inspection method for reinforced concrete bodies using so-called electromagnetic wave radar is known, for example, as disclosed in Patent Document 1 (JP Patent Publication No. 2005-331404). According to the non-destructive inspection method for reinforced concrete bodies in Patent Document 1, by irradiating the reinforced concrete body with an electromagnetic wave radar, it is possible to estimate the positions of the reinforcing bars and voids inside the reinforced concrete body by utilizing the fact that reflected wave data at the positions of the reinforcing bars and voids inside the reinforced concrete body differs from reflected wave data at the concrete portion.

JP 2005-331404 A

The non-destructive inspection method for reinforced concrete bodies disclosed in Patent Document 1 estimates the depth position of rebars and void positions inside the reinforced concrete body by having an analyst observe the reflected wave data obtained by irradiating the reinforced concrete body with an electromagnetic radar. As a result, the accuracy of the inspection results depends in part on the analyst's experience and intuition, and the analyst must visually observe a huge amount of reflected wave data, so there is a need for a more efficient non-destructive inspection method for reinforced concrete bodies. For such non-destructive inspection of reinforced concrete bodies, it is considered necessary to propose a technology that can accurately determine the depth position and spacing of rebars inside the reinforced concrete body in a short period of time.

The present invention is therefore intended to solve the above problems, and has the following objectives: to provide a method for estimating the depth position of rebars in a reinforced concrete body that can quickly and accurately determine the depth position and spacing of rebars inside the reinforced concrete body.

As a result of intensive research by the inventors to solve the above problems, the inventors have come up with the following configuration. That is, the present invention is a method for estimating a reinforcing bar depth position of a reinforced concrete body, comprising : a first divided reflected wave data generating step of generating first divided reflected wave data by dividing reflected wave data of an electromagnetic wave obtained by irradiating an electromagnetic wave in a depth direction while moving on a traveling surface located above a reinforced concrete body in the extension direction of the reinforced concrete body, the first divided reflected wave data being divided for each required length in the extension direction; a second divided reflected wave data generating step of generating second divided reflected wave data by dividing the first divided reflected wave data for each required depth range of the reinforced concrete body; a Fourier transform data generating step of performing a Fourier transform on a change in reflection intensity of each of the second divided reflected wave data in each of the first divided reflected wave data in the extension direction to generate Fourier transform data; a specific frequency component presence/absence confirmation step of confirming the presence or absence of a specific frequency component in the Fourier transform data; a reinforcing bar depth position extraction step of extracting a position where the specific frequency component is confirmed in the specific frequency component presence/absence confirmation step as a reinforcing bar depth position; and a reinforcing bar pitch calculation step of calculating a reinforcing bar pitch in the extension direction of the reinforced concrete body based on the specific frequency component .

This makes it possible to provide a simple and highly accurate method for estimating the depth position of rebars in a reinforced concrete body without relying on the experience or intuition of an analyst. Also, the reflected wave data obtained over a long distance using an irradiation device mounted on a vehicle can be divided and processed by appropriate section lengths, making it possible to process data in a short time and estimating the spacing of rebars in the extension direction of the reinforced concrete body.

In addition, it is preferable that the reinforcing bar depth position extraction step extracts, as the reinforcing bar depth position, a depth position corresponding to the second divided reflected wave data in which the specific frequency component is confirmed .

It is preferable that the method further includes an interface reflected wave data extraction step of extracting, as interface reflected wave data, the second divided reflected wave data in which the difference in reflection intensity between the second divided reflected wave data adjacent in the depth direction on the running surface side of the reinforcing bar depth position extracted by the reinforcing bar depth position extraction step exceeds a predetermined threshold value; a running surface height position extraction step of extracting, as the running surface height position, the depth position corresponding to the interface reflected wave data in which the reflection intensity is maximum among the interface reflected wave data; and a reinforced concrete body upper surface height position extraction step of extracting, as the reinforced concrete body upper surface height position, the depth position corresponding to the interface reflected wave data existing between the running surface height position and the reinforcing bar depth position.

This makes it possible to more easily and accurately estimate the positions of the vehicle's running surface and the top surface of the reinforced concrete body based on the reflected wave data obtained by irradiating electromagnetic waves onto the reinforced concrete body while a vehicle equipped with an electromagnetic wave irradiation device is running.

In addition, after the rebar depth position extraction process is performed, it is preferable to perform the Fourier transform data generation process, the specific frequency component presence/absence confirmation process, and the rebar depth position extraction process on the next reflected wave data in the extension direction.

This makes it possible to estimate the height position of the driving surface (pavement surface) and the top surface of the reinforced concrete body , which cannot be seen directly from the driving surface, when pavement is laid on top of the reinforced concrete body.

According to the present invention, it is possible to provide a simple and highly accurate method for estimating the depth position of reinforcing bars in a reinforced concrete body without relying on the experience or intuition of an analyst. Also, it is possible to divide and process reflected wave data obtained over a long distance using an irradiation device mounted on a vehicle into appropriate intervals, which enables data processing in a short time and also makes it possible to estimate the spacing of reinforcing bars in the extension direction of a reinforced concrete body.

1 is a schematic configuration diagram of a reinforced concrete body reinforcing bar depth estimation system according to an embodiment of the present invention; 1 is a schematic process diagram of a method for estimating reinforcing bar depth in a reinforced concrete body according to an embodiment of the present invention. FIG. This is an image diagram of reflected wave data obtained by irradiating an electromagnetic radar onto a reinforced concrete body. FIG. 4 is an explanatory diagram showing an example in which the reflected wave data shown in FIG. 3 is divided into required ranges in the extension direction. FIG. 13 is an explanatory diagram showing the positions of divided data at a required depth position of a reinforced concrete body. FIG. 6 is a plot diagram showing the intensity of reflected signals in the divided data of FIG. 5 . FIG. 7 is a correlation diagram between amplitude and frequency showing a state in which the plot diagram shown in FIG. 6 is subjected to Fourier transform processing. 6 is an explanatory diagram showing the positions of divided data at a depth position different from that in FIG. 5; FIG. 9 is a plot diagram showing the intensity of reflected signals in the divided data of FIG. 8 . FIG. 10 is a correlation diagram between amplitude and frequency showing a state in which the plot diagram shown in FIG. 9 is subjected to Fourier transform processing. FIG. 1 is an explanatory diagram showing an analysis range consisting of a required range in the extension direction and a required depth range of a reinforced concrete body. 12 is a spectrogram in the analysis range shown in FIG. 11 . FIG. 13 is an explanatory diagram showing a state in which the analysis ranges in a reinforced concrete body partially overlap in the extension direction. 11A and 11B are explanatory diagrams of reflected wave data in an example in which the number of noteworthy sample data in the reflected wave data is reduced. 15 is an explanatory diagram showing a reflection intensity plot diagram and Fourier transform data of reflected wave data in a representative depth direction in FIG. 14 . FIG. This is a spectrogram summarizing the Fourier transform data in the depth direction in the detailed area of interest of the rebar position. FIG. 1 is an explanatory diagram showing an example of reflected wave data and a spectrogram of an RC slab including a damaged area. 10 is a conceptual diagram for calculating a travel surface height position and a boundary surface height position based on reflected wave data. FIG.

As shown in FIG. 1, the reinforced concrete body rebar depth position estimation device (hereinafter referred to as rebar position estimation device 100) in this embodiment is mounted on a vehicle VH that travels on the top surface (travel surface) of an RC slab 10 as a reinforced concrete body. The rebar position estimation device 100 includes an electromagnetic wave radar 20 attached to the front position of the vehicle VH and a computer 30 disposed inside the vehicle VH. The computer 30 in the reinforced concrete body rebar position estimation device 100 in this embodiment can be in a portable form such as a notebook computer, or a computer 30 separate from the vehicle VH can be used. A reinforced concrete body rebar depth position estimation program (hereinafter referred to as program PGM) is pre-stored (installed) in the memory unit 32 of the computer 30.

The electromagnetic wave radar 20 in this embodiment has an electromagnetic wave emitting section 22 and a reflected wave receiving section 24, with the electromagnetic wave emitting section 22 disposed forward in the traveling direction (scanning direction) of the vehicle VH, and the reflected wave receiving section 24 disposed rearward in the traveling direction of the electromagnetic wave emitting section 22. The on/off operation of the electromagnetic wave radar 20 is switched by an assistant aboard the vehicle VH or the driver before or after driving by operating an on/off switch (not shown). As shown in FIG. 1, the electromagnetic wave radar 20 in this embodiment is attached to the front end (front bumper (not shown)) of the vehicle VH, but the electromagnetic wave radar 20 can also be attached to the bottom or rear end (rear bumper) of the vehicle VH, or to a towing vehicle (not shown).

In this embodiment, the electromagnetic wave emitting unit 22 and the reflected wave receiving unit 24 of the electromagnetic wave radar 20 have multiple channels in the width direction of the vehicle VH (the direction perpendicular to the running direction in the horizontal plane). The electromagnetic wave emitting unit 22 and the reflected wave receiving unit 24 have the same number of channels, and the channels form pairs. This allows the electromagnetic wave emitting unit 22 to emit electromagnetic waves for each divided area 12 obtained by dividing the RC slab 10, which is the object of the survey, at required intervals in a direction perpendicular to the extension direction of the RC slab 10 in the horizontal plane, and the reflected wave receiving unit 24 to receive the reflected waves for each divided area 12. The reflected wave data HSD received by the reflected wave receiving unit 24 is sequentially stored in the memory unit 32 of the computer 30 by the control unit 34 in a state linked to each divided area 12.

The control unit 34 of the computer 30 can be exemplified by a CPU and a GPU. The control unit 34 operates as various functions to execute the method for estimating the depth position of rebar in a reinforced concrete body based on the program PGM. The specific functions and their contents will be described later.

Next, a method for estimating the depth position of rebars in a reinforced concrete body using the rebar position estimation device 100 described above will be described. FIG. 2 is a schematic process diagram of the method for estimating the depth position of rebars in a reinforced concrete body according to this embodiment. As shown in FIG. 1, the measurer operates a start switch (not shown) mounted on the vehicle VH while driving the vehicle VH equipped with the rebar position estimation device 100 in the extension direction of the RC slab 10, which is the reinforced concrete body to be inspected, to cause the control unit 34, which has a reflected wave data collection function, to collect reflected wave data HSD (S-1). The reflected wave data HSD collected in this way can be represented as grayscale image data as shown in FIG. 3. The reflected wave data HSD obtained in this way is stored in the memory unit 32 in a state linked to the divided areas 12 divided in the extension direction and width direction of the RC slab 10.

The grayscale image data shown in FIG. 3 is an image of the required length and depth range of the RC slab 10 in the extension direction. In this embodiment, a range of 1.2 m in the extension direction of the RC slab 10 and a range of 18 cm in the depth direction are extracted. The extraction range of the grayscale image based on the reflection intensity of the reflected wave data HSD, which is the extraction range of the reflected wave data HSD, is not limited to the numerical values in this embodiment, and any extraction range can be set. In addition, in the grayscale image data in FIG. 3, the part with the highest reflection intensity of the reflected wave data HSD appears as a black part, and the part with the lowest reflection intensity of the reflected wave data HSD appears as a white part, and is represented in gray gradations according to the reflection intensity of the reflected wave data HSD at each point in the extraction range.

The control unit 34 as the first divided reflected wave data generating function executes a first divided reflected wave data generating step (S-2) in which the reflected wave data HSD shown in FIG. 3 is divided into a predetermined required length range in the extension direction of the RC slab 10 to generate the first divided reflected wave data BHSD1. The required range is the range indicated by the arrow in FIG. 4, which is a range of 256 sample data in this embodiment. Next, the control unit 34 as the second divided reflected wave data generating function executes a second divided reflected wave data generating step (S-3) in which the first divided reflected wave data BHSD1 is divided into a predetermined required depth (1 mm intervals in this embodiment) to generate the second divided reflected wave data BHSD2. In this way, the reflected wave data HSD is divided into a plurality of first divided reflected wave data BHSD1, and each of the first divided reflected wave data BHSD1 is divided into a plurality of second divided reflected wave data BHSD2. The division intervals of the first divided reflected wave data BHSD1 and the second divided reflected wave data BHSD2 are not limited to the division intervals in this embodiment, and any division interval can be adopted.

Next, a method of analyzing a certain first divided reflected wave data BHSD1 will be described. The control unit 34, which functions as a specific depth position reflected wave plot function, executes a specific depth position reflected wave plot generation process (S-4) to generate a plot of the reflected wave signal strength and the extension direction of the RC slab 10 (hereinafter sometimes referred to as the scanning direction) for each second divided reflected wave data BHSD2 in the first divided reflected wave data BHSD1, starting from the top row. As a specific example, the processing of the depth position indicated by the arrow in Figure 5 will be described. If the grayscale value at the position of the arrow in Figure 5 is taken as the value on the vertical axis and the scanning direction of the first divided reflected wave data BHSD1 (the direction in which the cumulative number of sample data increases) is taken as the horizontal axis, a specific depth position reflected wave plot PR shown in Figure 6 is obtained. When generating a specific depth position reflected wave plot PR using the second divided reflected wave data BHSD2 at a specific depth position, if there are multiple grayscale values in an area enclosed within a minimum division range that was previously set when dividing the second divided reflected wave data BHSD2, the average value of each grayscale value can be used.

Next, the control unit 34, which functions as a Fourier transform data generation function, executes a Fourier transform data generation step (S-5) in which a fast Fourier transform is performed on the specific depth position reflected wave plot PR shown in FIG. 6 in the scanning direction to generate Fourier transform data FTD. Note that before executing the Fourier transform data generation step, the control unit 34 can also execute a process of multiplying the specific depth position reflected wave plot PR by a Hilbert variable. This makes it possible to prevent the frequency data output in the Fourier transform from having negative components, and allows comparison only in the positive region. FIG. 7 shows Fourier transform data FTD showing the relationship between amplitude and frequency, which shows the result of Fourier transform processing of the specific depth position reflected wave plot PR in FIG. 6. In the Fourier transform data FTD in FIG. 7, the fluctuation in reflection intensity in the specific depth position reflected wave plot PR where the Fourier transform processing is performed is small, so the graph shows a prominent 0 for the specific frequency. In other words, it can be determined that the internal structure of the RC slab 10 in the scanning direction is uniform at the depth position in FIG. 5.

In contrast, if the specific reflected wave plot generation process is performed at the depth position indicated by the arrow in Figure 8 in the same manner as for the depth position shown in Figure 5, a specific depth position reflected wave plot PR as shown in Figure 9 is obtained. Figure 10 shows the Fourier transform data FTD obtained by performing the Fourier transform data generation process in the scanning direction of this specific depth position reflected wave plot PR. Unlike the Fourier transform data FTD shown in Figure 7, the Fourier transform data FTD in Figure 10 has peaks in parts other than where the frequency is 0, as shown by the arrow in Figure 10. This peak means that foreign objects (here, rebars) are present at required intervals inside the RC slab 10.

The control unit 34 repeatedly executes a specific depth position reflected wave plot generation process and a Fourier transform data generation process for the entire depth direction of the first divided reflected wave data BHSD1 (the area surrounded by a square in FIG. 11). The Fourier transform data FTD corresponding to each of the second divided reflected wave data BHSD2 obtained in this manner is overlapped in the depth direction by the control unit 34 as a depth direction overlap data generation function to generate depth direction overlap data (not shown) in a depth direction overlap data generation process (S-6).

Next, the control unit 34 as a spectrogram generating function executes a spectrogram generating step (S-7) to generate a spectrogram SPC as shown in FIG. 12 from the depth direction overlapping data. When a spectrogram SPC as shown in FIG. 12 is generated, the strength of the reflected wave data HSD in the first divided reflected wave data BHSD1 can be represented in a color-coded state. Then, the control unit 34 as a scanning direction data synthesizing function executes a scanning direction data synthesizing step (S-8) to generate scanning direction synthesized data SGD that synthesizes the first divided reflected wave data BHSD1 over the entire range of the scanning direction.

At this time, the control unit 34 can also generate the scanning direction synthetic data SGD in a state in which the required ranges in the scanning direction of the first divided reflected wave data BHSD1 adjacent to each other in the scanning direction are overlapped with each other, as shown in FIG. 13. Specifically, of the first divided reflected wave data BHSD1 adjacent to each other in the front and rear of the scanning direction, 50 sample data on the end side of the first divided reflected wave data BHSD1 located in the front and 50 sample data on the tip side of the first divided reflected wave data BHSD1 located in the rear are overlapped with each other. By performing such processing, the continuity of the spectrogram SPC in the first divided reflected wave data BHSD1 is guaranteed, and the estimation accuracy of the depth position and installation interval of the reinforcing bars can be improved.

The above process may be repeated in the entire extension direction of the RC slab 10 to be surveyed to obtain a spectrogram SPC in the entire extension direction of the RC slab 10. The control unit 34 as a specific frequency component presence/absence confirmation function executes a specific frequency component presence/absence confirmation process to confirm the presence/absence of a specific frequency component from the spectrogram SPC in the entire extension direction of the RC slab 10 (S-9). When a specific frequency component is confirmed by the specific frequency component presence/absence confirmation process, the control unit 34 as a reinforcing bar depth position extraction function executes a reinforcing bar depth position extraction process to extract the depth position at which a specific frequency response corresponding to the reinforcing bar pitch appears as the reinforcing bar depth position TFI (depth position of arrow A in FIG. 12) (S-10). At this time, the control unit 34 as a reinforcing bar pitch calculation function can also execute a reinforcing bar pitch calculation process to extract the normalized frequency (length corresponding to the number of data samples: normalized frequency of arrow B in FIG. 12) at the reinforcing bar depth position TFI as the reinforcing bar arrangement interval TKP in the extension direction of the RC slab 10 (S-11).

When estimating the rebar depth position TFI in an RC slab 10 in a bridge or the like, if the number of sample data is large, the number of rebars included in the reflected wave data HSD may be too large. In addition, the depth position of rebars in most reinforced concrete bodies, including RC slabs 10, is in the range of 10 to 35 cm, and the rebar pitch is often 5 to 20 cm. Therefore, in practice, a method of estimating the depth position of rebars by setting a certain number of conditions like these is sometimes adopted. Figure 14 shows the reflected wave data HSD in a form in which the number of sample data is set to 0 to 64 for the first divided reflected wave data BHSD1 of the previous embodiment. For each of the second divided reflected wave data BHSD2 divided in the required depth direction for BHSD1 in Figure 14, a specific depth position reflected wave plot PR and Fourier transform data FTD obtained by Fourier transforming this are calculated as shown in Figure 15. In addition, in Figure 15, the specific depth position reflected wave plot PR and Fourier transform data FTD are shown only for the representative depth positions (10 cm, 20 cm, 30 cm).

Then, by compiling the Fourier transform data FTD over the entire depth direction of the first divided reflected wave data BHSD1 and then generating a spectrogram SPC as shown in FIG. 16, the depth position of the foreign object (reinforcing bar) inside the RC slab 10 and the spacing of the reinforcing bars can be estimated in more detail. Since the color tone of the area circled and indicated by the arrow in the spectrogram SPC in FIG. 16 is clearly different from the surrounding area, this part can be estimated as the depth position of the reinforcing bars (value on the vertical axis) and the spacing of the reinforcing bars (value on the horizontal axis).

In addition, when there is a damaged area inside the RC slab 10, the reflected wave data HSD often has a state in which continuity in the scanning direction is broken, as shown in Figure 17. For the damaged area SSH in Figure 17, the spectrogram SPC obtained by processing the reflected wave data HSD in the same manner as described above shows that the difference between the color tone of the frequency indicating the depth position of the rebar and the spacing of the rebar corresponding to Figure 16 and the surrounding color tone is less clear than in Figure 16. In other words, by making the spectrogram SPC of the same depth range continuous across the scanning direction, it becomes possible to estimate the depth position of the rebar and the position of the damaged area in the scanning direction, respectively.

As explained above, by applying a Fourier transform to the reflected wave data HSD obtained by irradiating the RC slab 10 with electromagnetic waves from the electromagnetic radar 20 in the extension direction of the RC slab 10, the depth position and spacing of the reinforcing bars inside the RC slab 10 can be estimated efficiently in a short time. In addition, by creating a spectrogram SPC for the entire range of the reflected wave data HSD, the depth position and spacing of the reinforcing bars can be visually determined when the analyst performs the analysis, which is advantageous in that the analyst can efficiently perform reconfirmation work.

Also, as shown in FIG. 18, if the difference in reflection intensity of the reflected wave data HSD in the required depth range (adjacent second divided reflected wave data BHSD2 in the depth direction) on the running surface side (upper side in FIG. 18) of the rebar depth position TFI extracted by the rebar depth position extraction step (S-10) exceeds a preset threshold value, an interface reflected wave data extraction step (S-12) can be executed to extract the second divided reflected wave data BHSD2 with the higher reflection intensity as the interface reflected wave data KHSD. Following this, a running surface height position extraction step (S-13) can be executed to extract the depth position of the second divided reflected wave data BHSD2 corresponding to the maximum interface reflected wave data KHSDm with the highest reflection intensity among the interface reflected wave data KHSD as the running surface height position SKMT. Note that in FIG. 18, there is only one interface reflected wave data KHSD, so this becomes the maximum interface reflected wave data KHSDm.

Furthermore, a reinforced concrete body top surface height position extraction process (S-14) can be executed to extract the depth position of the second divided reflected wave data BHSD2 corresponding to the boundary surface reflected wave data KHSD existing between the running surface height position SKMT and the reinforcing bar depth position TFI that exceeds a preset second threshold as the reinforced concrete body top surface height position TKJT. In addition, since the top surface of the RC slab 10 is the running surface in FIG. 18, the height positions of the running surface height position SKMT and the reinforced concrete body top surface height position TKJT are the same in FIG. 18. Normally, multiple reactions occur in the reflected wave data HSD due to ringing, so it is not easy to estimate the boundary surface of the top surface of the RC slab 10, the top surface of the pavement, etc. In contrast, the present invention is advantageous in that it is possible to estimate the depth position of the reinforcing bar, and therefore it is possible to estimate the boundary surface between the reinforcing bar and the running surface from the reaction of the reflected wave at the reinforcing bar and the running surface.

In addition, the boundary surface reflected wave data extraction step (S-12), the running surface height position extraction step (S-13), and the reinforced concrete body top surface height position extraction step (S-14) can be omitted. In the above description, the boundary surface reflected wave data extraction step (S-12), the running surface height position extraction step (S-13), and the reinforced concrete body top surface height position extraction step (S-14) are performed after the reinforcing bar depth position extraction step (S-10), but this is not limited to this form. At any timing after the specific depth position reflected wave plot generation step (S-4) is performed, the boundary surface reflected wave data extraction step (S-12), the running surface height position extraction step (S-13), and the reinforced concrete body top surface height position extraction step (S-14) can be performed.

In the above embodiment, when creating the specific depth position reflected wave plot PR, the average value of multiple grayscale values in the area enclosed by the preset required depth range and the minimum division range in the scanning direction when dividing the second divided reflected wave data BHSD2 is used, but this is not limited to this form. It is also possible to use a form in which the grayscale value at the center point of the area enclosed by the preset required depth range and the minimum division range in the scanning direction when dividing the second divided reflected wave data BHSD2 is used as the representative value.

In addition to the modifications described above, it is also possible to adopt a form that appropriately combines the modifications described in the embodiments.

10: RC slab (reinforced concrete body)
12: divided area 20: electromagnetic wave radar 22: electromagnetic wave emitting unit, 24: reflected wave receiving unit 30: computer 32: memory unit, 34: control unit 100: reinforcing bar position estimating device (reinforced concrete body reinforcing bar depth position estimating device)
BHSD1: First divided reflected wave data BHSD2: Second divided reflected wave data FTD: Fourier transform data HSD: Reflected wave data KHSD: Boundary surface reflected wave data KHSDm: Maximum boundary surface reflected wave data PGM: Program (reinforced concrete body rebar depth position estimation program)
PR: Plot of reflected waves at specific depths SGD: Scanning direction composite data SKMT: Height of running surface SPC: Spectrogram SSH: Damage area TFI: Reinforcement depth position TKJT: Height of upper surface of reinforced concrete body TKP: Reinforcement interval VH: Vehicle

Claims (4)

a first divided reflected wave data generating step of generating first divided reflected wave data by dividing the reflected wave data of the electromagnetic wave obtained by irradiating the electromagnetic wave in a depth direction while moving on a traveling surface located above the reinforced concrete body in the extension direction of the reinforced concrete body for each required length in the extension direction;
a second divided reflected wave data generating step of generating second divided reflected wave data by dividing the first divided reflected wave data for each required depth range of the reinforced concrete body;
a Fourier transform data generating step of performing a Fourier transform on a change in reflection intensity of each of the second divided reflected wave data in each of the first divided reflected wave data in the extension direction to generate Fourier transform data;
a step of confirming whether or not a specific frequency component exists in the Fourier transform data;
a reinforcing bar depth position extraction step of extracting a position where the specific frequency component is confirmed as a reinforcing bar depth position in the specific frequency component presence/absence confirmation step;
a reinforcement pitch calculation step of calculating a reinforcement pitch in the extension direction of the reinforced concrete body based on the specific frequency component . The reinforcing bar depth position extraction step includes:
A method for estimating the depth position of reinforcing bars in a reinforced concrete body according to claim 1, characterized in that a depth position corresponding to the second divided reflected wave data in which the specific frequency component is confirmed is extracted as the reinforcing bar depth position . an interface reflected wave data extraction process for extracting, as interface reflected wave data, the second divided reflected wave data in which the difference in reflection intensity between the second divided reflected wave data adjacent in the depth direction on the traveling surface side of the reinforcing bar depth position extracted in the reinforcing bar depth position extraction process exceeds a preset threshold value;
a travel surface height position extraction step of extracting, as a travel surface height position, a depth position corresponding to the boundary surface reflected wave data in which the reflection intensity is maximum from the boundary surface reflected wave data;
3. The method for estimating the reinforcing bar depth position of a reinforced concrete body as described in claim 1 or 2, further comprising a reinforced concrete body top surface height position extraction process for extracting a depth position corresponding to the boundary surface reflected wave data existing between the running surface height position and the reinforcing bar depth position as the reinforced concrete body top surface height position. After the reinforcing bar depth position extraction process is performed, the next reflected wave data in the extension direction is
A method for estimating the depth position of reinforcing bars in a reinforced concrete body according to any one of claims 1 to 3 , characterized in that the Fourier transform data generation process, the specific frequency component presence/absence confirmation process, and the reinforcing bar depth position extraction process are carried out.

Images