JP7642202B2 - Utility pole deterioration diagnosis method and utility pole deterioration diagnosis system - Google Patents

Description

The present invention relates to a utility pole deterioration diagnosis method and utility pole deterioration diagnosis system for diagnosing deterioration of reinforcing bars in utility poles with reinforced concrete structure.

Understanding the state of corrosion of the internal rebar is important for evaluating the strength of reinforced concrete utility poles. It has been revealed that the main deterioration process of reinforced concrete utility poles is a "crack-first" type, where cracks appear on the surface of the pole, which then progresses to rebar corrosion. Utility pole maintenance inspections are generally performed by visually inspecting the exterior for abnormalities. However, it is difficult to accurately evaluate the strength of internal rebar deterioration from cracks that appear on the concrete surface.

A diagnostic method using a non-destructive inspection device that uses X-ray transmission is known as a method for inspecting the condition of internal rebars (see Patent Document 1). Specifically, the non-destructive inspection device includes an X-ray source that irradiates the utility pole with X-rays, an imaging device that detects the X-rays emitted from the X-ray source and transmitted through the utility pole, and a control unit that generates an image based on a signal from the imaging device. With this technology, the rebars inside the utility pole can be generated as an X-ray transmission image.

Patent No. 6763526

However, in the conventional technology of Patent Document 1, for example, when only a portion of the circumferential surface of a reinforcing bar is thinned, imaging from one direction may not be able to obtain the outline of the thinned portion of the reinforcing bar, so it is necessary to capture multiple images from different angles. Furthermore, the application of such a method of capturing multiple images from different angles is limited in places with a lot of pedestrian traffic, such as urban areas, due to the risk of traffic obstruction and radiation damage.
Furthermore, in the conventional technology of Patent Document 1, in order to diagnose the deterioration state of the reinforcing bars based on X-ray transmission images, the diagnosis must be done visually by a skilled technician, which poses the problem that it is not possible to quantitatively evaluate the strength of the utility pole.

Therefore, the present invention aims to diagnose the deterioration of the reinforcing bars inside reinforced concrete utility poles in a short time with as few images as possible, and to quantitatively evaluate the strength of the utility poles.

In order to solve the above problem, the utility pole deterioration diagnosis method of the present invention is a utility pole deterioration diagnosis method for diagnosing deterioration of a utility pole having a cylindrical concrete pole and a plurality of reinforcing bars embedded in the concrete pole in a circumferentially aligned manner, and includes an image acquisition process in which an X-ray irradiation device is disposed facing the outer circumferential surface of the utility pole and an imaging panel is disposed on the opposite side of the utility pole from the X-ray irradiation device, and then X-rays are irradiated from the X-ray irradiation device to obtain an X-ray transmission image in which multiple reinforcing bars extending vertically of the utility pole are aligned horizontally; and a remaining wall thickness estimation process in which the utility pole deterioration diagnosis device analyzes the X-ray transmission image to identify deteriorated parts of the reinforcing bars based on the brightness of the reinforcing bar image, obtains a deteriorated part brightness profile, which is a profile of the brightness of multiple pixels aligned horizontally in the image corresponding to the deteriorated part, and estimates the remaining wall thickness of the reinforcing bars based on the peak area of the deteriorated part brightness profile.

In addition, the utility pole deterioration diagnosis system of the present invention is a utility pole deterioration diagnosis system for diagnosing deterioration of a utility pole having a cylindrical concrete pole and a plurality of reinforcing bars embedded in the concrete pole in a circumferentially aligned manner, and comprises an X-ray irradiation device that irradiates X-rays, an imaging panel that is arranged on the opposite side of the utility pole from the X-ray irradiation device and acquires X-ray transmission images of multiple reinforcing bars extending vertically of the utility pole lined up horizontally, and a utility pole deterioration diagnosis device that analyzes the X-ray transmission images acquired by the imaging panel.
The utility pole deterioration diagnosis device identifies deteriorated portions of rebars based on the brightness of the rebar image, obtains a deteriorated portion brightness profile which is a profile of the brightness of multiple pixels arranged horizontally in the image corresponding to the deteriorated portion, and estimates the remaining amount of rebar material based on the peak area of the deteriorated portion brightness profile.

According to this utility pole deterioration diagnosis method and utility pole deterioration diagnosis system, the deteriorated parts of the rebar are identified based on the brightness of the rebar image, and the remaining amount of rebar is estimated based on the peak area of the deteriorated part brightness profile in the image corresponding to the deteriorated part. This makes it possible to diagnose the deterioration status of the rebar in a short time with as few images as possible, and to quantitatively evaluate the strength of the utility pole.

In addition, in the utility pole deterioration diagnosis method, a deterioration degree RT indicating the degree of deterioration of the reinforcing bars is calculated based on the remaining wall amount estimated in the remaining wall amount estimation process, and the deterioration degree of each of the n reinforcing bars in the portion of the concrete pole to which a tensile load is applied is defined as RTn, the distance from the nth reinforcing bar in the portion to which the tensile load is applied to the neutral plane is defined as ln, and the deterioration degree of the utility pole is defined as RP.
RP = Σ(RTn×ln)
The deterioration degree RP of the utility pole may be calculated in this manner to evaluate the utility pole.

The utility pole deterioration diagnosis method may also include a remaining wall thickness estimation step of estimating the remaining wall thickness ratio of the rebar by comparing a first area, which is a peak area of the deteriorated portion brightness profile, with a second area corresponding to the peak area of the brightness profile of the portion where the rebar is not deteriorated.

This allows the rebar's remaining wall thickness to be estimated with high accuracy.

The utility pole deterioration diagnosis method also includes a rebar position identification process for identifying at least one rebar position Xn, which is the horizontal position of the rebar, for each rebar image in the X-ray transmission image; a rebar brightness acquisition process for acquiring a rebar brightness profile, which is a profile of the brightness of multiple pixels arranged vertically at the rebar position Xn in the X-ray transmission image; and a determination process for determining that the rebar corresponding to the rebar position Xn is deteriorated when a peak with a locally higher brightness than the surrounding area is detected in the rebar brightness profile. The method may identify a peak position Yp, which is the vertical position of the X-ray transmission image corresponding to the peak of the rebar brightness profile, and acquire the deteriorated portion brightness profile at the peak position Yp of the X-ray transmission image.

This makes it possible to determine which of multiple rebars arranged horizontally are deteriorated.

In addition, in the reinforcing bar position identification process, a position identification profile, which is a profile of the brightness of multiple pixels arranged horizontally at at least one vertical position in the X-ray transmission image, may be obtained, a peak position Xp where the brightness becomes small may be detected in the position identification profile, and the reinforcing bar position Xn may be identified based on the peak position Xp.

In addition, in the reinforcing bar position identification process, a position shifted from the lateral center of the reinforcing bar image may be determined as the reinforcing bar position Xn.

This allows a rebar brightness profile to be obtained for the portion near the outer periphery of the rebar where thinning occurs from the outer periphery side, making it possible to obtain the rebar brightness profile of the thinned portion.

In addition, in the remaining wall ratio estimation process, a comparison position Yc, which is a vertical position of the X-ray transmission image away from the peak of the rebar brightness profile, may be determined, and a comparison brightness profile, which is a profile of the brightness of multiple pixels arranged horizontally at the comparison position Yc of the X-ray transmission image, may be obtained, and the peak area of the comparison brightness profile may be calculated as the second area.

The present invention makes it possible to diagnose the deterioration of the reinforcing steel inside a reinforced concrete utility pole in a short time with as few images as possible, and to quantitatively evaluate the strength of the utility pole.

1 is a diagram showing a utility pole deterioration diagnosis system according to an embodiment of the present invention. 1A and 1B are diagrams showing an example of a method for photographing reinforcing bars inside a utility pole. 1A is a diagram showing an X-ray image, FIG. 1B is a diagram showing a position identification profile, and FIG. 1C is an enlarged view for explaining a method for identifying the position of the first reinforcing bar. FIG. 4A shows an X-ray transmission image, and FIG. 4B shows a rebar brightness profile. 1A is an enlarged view of an image of a deteriorated portion of a rebar, FIG. 1B is a luminance profile of the deteriorated portion, and FIG. 1C is a comparative luminance profile. FIG. 1A is a diagram showing the state in which a bending load is applied to a utility pole, and FIG. 1B is a B-B cross-sectional view showing the distance between the reinforcing bar and the neutral plane. 4 is a flowchart showing the operation of the utility pole deterioration diagnosis device. 13A to 13F show the peak areas of the brightness profile of the deteriorated part of the rebar when the outline of the deteriorated part of the rebar can be obtained and when it cannot be obtained due to differences in the shooting direction. FIG. 13 is a diagram showing an example in which multiple reinforcing bar positions are set for one reinforcing bar image.

Next, an embodiment of the present invention will be described in detail with reference to the drawings as appropriate.
As shown in Fig. 1, the utility pole deterioration diagnosis system 1 is a system for diagnosing the deterioration of a utility pole 2. The utility pole 2 has a cylindrical concrete pole 21 and a plurality of reinforcing bars 22 embedded in the concrete pole 21 so as to be aligned in the circumferential direction.

The utility pole deterioration diagnosis system 1 includes an X-ray irradiation device 11, an imaging panel 12, a utility pole deterioration diagnosis device 13, a first cover 14, and a second cover 15. The X-ray irradiation device 11 is a device that irradiates X-rays, and is fixed to the utility pole 2 so as to face the outer circumferential surface of the utility pole 2.

The imaging panel 12 is a panel that detects X-rays from the X-ray irradiation device 11 that have passed through the utility pole 2, and obtains an X-ray transmission image of the horizontal rows of reinforcing bars 22 that extend vertically on the utility pole 2. The imaging panel 12 is disposed on the opposite side of the utility pole 2 from the X-ray irradiation device 11, and is fixed to the utility pole 2. The imaging panel 12 is, for example, a flat panel detector that can detect X-rays, and has a light receiving section in which pixels are arranged in a matrix. Each pixel of the imaging panel 12 is, for example, provided with a pixel that accumulates an electric charge corresponding to the amount of X-rays received, and a control circuit. This allows an electrical signal corresponding to the amount of X-rays received from each pixel to be output to the utility pole deterioration diagnosis device 13 via an analog-digital conversion circuit disposed at the end.

The first cover 14 is a member that covers the X-ray irradiation device 11 and is fixed to the utility pole 2. The second cover 15 is a member that covers the imaging panel 12 and is fixed to the utility pole 2. The first cover 14 and the second cover 15 are made of, for example, lead that blocks X-rays, and can keep the radiation level on the surface of the device below the standard value (0.6 μSv/h).

The utility pole deterioration diagnosis device 13 is a device that analyzes the X-ray transmission images acquired by the imaging panel 12 to determine the deterioration of the reinforcing bars. The utility pole deterioration diagnosis device 13 is equipped with a screen 13A that displays the images, and a control unit (not shown). The control unit has a CPU, ROM, RAM, rewritable non-volatile memory, etc., and executes a program that has been stored in advance.

The X-ray irradiation device 11, the imaging panel 12, and each cover 14, 15 can be fixed at any position in the circumferential direction on the outer periphery of the utility pole 2. This makes it possible to select the reinforcing bar 22 to be subjected to deterioration judgment and obtain an X-ray transmission image of the selected reinforcing bar 22.

Specifically, as shown in Figs. 2(a) and 2(b), for example, the reinforcing bars 22 to be subjected to deterioration judgment can be selected from the reinforcing bars 22 placed in the cylindrical concrete pole 21 at the portion where the tensile load is applied. Here, the utility pole 2 is subjected to bending moments due to the forces of overhead lines and wind, so that a tensile load is applied to a portion of the concrete pole 21 and a compressive load is applied to the other portion. Since concrete has characteristics that are strong against compression and weak against tension, the current strength of the utility pole 2 can be accurately evaluated by judging the deterioration of the reinforcing bars 22 placed on the tension side. The portion where the tensile load is applied can be identified, for example, by cracks formed on the outer surface of the concrete pole 21 or the position of the overhead lines attached to the utility pole 2. Fig. 2 shows an example in which a tensile load is applied to the portion of the concrete pole 21 on the left side of the straight line L1 indicating the neutral plane, and a compressive load is applied to the portion of the concrete pole 21 on the right side of the straight line L1.

When photographing multiple reinforcing bars 22 to be subjected to deterioration judgment, first, the X-ray irradiation device 11 and the imaging panel 12 are placed at the first position shown in FIG. 2(a) to obtain an X-ray transmission image. In detail, the imaging panel 12 is placed so as to face the outer peripheral surface of the portion of the concrete pole 21 to which a tensile load is applied. Then, the X-ray irradiation device 11 and the imaging panel 12 are rotated around the pole 2 and placed at the second position shown in FIG. 2(b) to obtain an X-ray transmission image. In this way, by appropriately rotating the X-ray irradiation device 11 and the imaging panel 12, etc., and photographing at different positions, it is possible to photograph all of the reinforcing bars 22 to which a tensile load is applied. In other words, in the photographing, all of the reinforcing bars 22 to which a tensile load is applied are photographed, and the reinforcing bars 22 to which a compressive load is applied are not photographed. This makes it possible to shorten the work time compared to, for example, photographing all of the reinforcing bars 22 arranged around the entire circumference of the concrete pole 21.

During imaging, the shadow of the reinforcing bar 22 on the compression side closer to the X-ray irradiation device 11 may overlap with the shadow of the reinforcing bar 22 on the tension side closer to the imaging panel 12. However, since the shadow of the reinforcing bar 22 on the compression side is a faint and blurred image, if the shading and contour of the image of the reinforcing bar 22 on the tension side are clear, the X-ray transmission image with the overlapping shadows can be used for the deterioration judgment described below. Note that deterioration judgment can be performed by acquiring multiple X-ray transmission images with different imaging angles and selecting an image of the reinforcing bar 22 on the tension side on which the shadow of the compression side is not overlapped from the multiple X-ray transmission images, so that the shadow of the compression side is not overlapped for all images of the reinforcing bar 22 on the tension side.

The utility pole deterioration diagnosis device 13 is capable of executing an image acquisition process, a deterioration determination process, a remaining wall thickness ratio estimation process including a remaining wall thickness estimation process, and an evaluation process. In the image acquisition process, the utility pole deterioration diagnosis device 13 acquires an X-ray transmission image G as shown in FIG. 3(a) from the imaging panel 12. In the deterioration determination process, the utility pole deterioration diagnosis device 13 analyzes the X-ray transmission image G to determine the deterioration of the reinforcing bar 22.

In detail, the deterioration assessment process includes a rebar position identification process, a rebar brightness acquisition process, and an assessment process. The rebar position identification process is a process for identifying at least one rebar position Xn, which is the lateral (X) position of the rebar 22, for one rebar image Gs in the X-ray transmission image G. In this embodiment, an example is shown in which only one rebar position Xn is identified for one rebar image Gs.

In the rebar position identification process, the utility pole deterioration diagnosis device 13 first obtains a position identification profile PF1 shown in FIG. 3(b), which is a profile of the brightness of multiple pixels arranged horizontally at a specific vertical position Ya in the X-ray transmission image G. Next, the utility pole deterioration diagnosis device 13 detects a peak position Xp where the brightness becomes small in the position identification profile PF1, and identifies the rebar position Xn based on the peak position Xp.

In detail, since the position identification profile PF1 includes peaks P1 to P8 corresponding to each of the multiple rebar images Gs1 to Gs8, the utility pole deterioration diagnosis device 13 detects peak positions Xp1 to Xp8 for each of the peaks P1 to P8. More specifically, when identifying the first peak position Xp1 corresponding to the first peak P1, the utility pole deterioration diagnosis device 13 plots a quadratic approximation curve that is close to the waveform of the first peak P1, and sets the horizontal position of the apex of this quadratic approximation curve as the first peak position Xp1. The first peak position Xp1 identified in this way is usually a position corresponding to the horizontal center of the first rebar image Gs1. After identifying the first peak position Xp1, the utility pole deterioration diagnosis device 13 identifies a position that is horizontally shifted from the first peak position Xp1 and within the horizontal width of the first rebar image Gs1 (within the horizontal range from the peak start to the peak end) as the first rebar position X1, as shown in FIG. 3(c). The method for identifying other rebar positions Xn is similar, so explanation is omitted.

The method of identifying the peak position Xp and the rebar position Xn may be other methods. For example, the midpoint of the horizontal range from the peak start to the peak end of the peak may be set as the peak position Xp corresponding to the horizontal center of the rebar image Gs, and the rebar position Xn may be identified using the method described above based on this peak position Xp. Also, the position of the peak top of the peak may be set as the peak position Xp, and the peak position Xp may be directly set as the rebar position Xn.

Note that multiple position identification profiles PF1 may be obtained by setting multiple predetermined vertical positions Ya for acquiring the position identification profile PF1. In this case, for example, the average value of multiple rebar positions Xn identified by each of the multiple position identification profiles PF1 may be set as the rebar position Xn.

The rebar brightness acquisition process is a process for acquiring a rebar brightness profile PF2, which is a profile of the brightness of multiple pixels arranged vertically at the rebar position Xn in the X-ray transmission image G, as shown in Figures 4(a) and (b). The example shown in Figures 4(a) and (b) shows the rebar brightness profile PF2 on the vertical line L2 at the fourth rebar position X4. When a deteriorated image Gd, such as the fourth rebar image Gs4, which is an image corresponding to a deteriorated part of the rebar 22, exists, the utility pole deterioration diagnosis device 13 detects a peak P11 in the rebar brightness profile PF2 that is locally brighter than the surrounding area. Specifically, the utility pole deterioration diagnosis device 13 detects, for example, a peak whose peak height is equal to or greater than a predetermined value as a peak P11 that is locally brighter than the surrounding area.

The judgment process is a process in which, if a peak P11 is detected in the rebar brightness profile PF2, the rebar 22 corresponding to the rebar position Xn is judged to be deteriorated. If the peak P11 is not detected in the judgment process, the utility pole deterioration diagnosis device 13 judges that the rebar 22 corresponding to the rebar position Xn is sound. If the utility pole deterioration diagnosis device 13 judges that the rebar 22 is deteriorated in the judgment process, it executes a remaining wall thickness estimation process.

The remaining wall thickness ratio estimation process is a process for estimating the remaining wall thickness ratio of the rebar 22. In the remaining wall thickness ratio estimation process, the utility pole deterioration diagnosis device 13 first determines a peak position Yp, which is a position in the vertical direction of the X-ray transmission image G corresponding to the peak P11 of the rebar brightness profile PF2, and a comparison position Yc, which is a position in the vertical direction of the X-ray transmission image G separated horizontally from the peak P11 of the rebar brightness profile PF2, as shown in FIG. 4(b). The method of determining the peak position Yp can be the same as the method of determining the peak position Xp described above, for example, by setting the position of the peak top of the peak P11 as the peak position Yp. The method of determining the comparison position Yc can be, for example, by setting a position separated by a predetermined distance from the peak position Yp as the comparison position Yc.

Next, as shown in FIG. 5(a), the utility pole deterioration diagnosis device 13 acquires a deteriorated portion brightness profile PF3 (see FIG. 5(b)), which is a brightness profile of multiple pixels arranged horizontally on a horizontal line L3 at a peak position Yp of the X-ray transmission image G (an enlarged image is shown in FIG. 5). The utility pole deterioration diagnosis device 13 also acquires a comparison brightness profile PF4 (see FIG. 5(c)), which is a brightness profile of multiple pixels arranged horizontally on a horizontal line L4 at a comparison position Yc of the X-ray transmission image G.

In detail, as shown in FIG. 5(a), a horizontal range R includes one rebar image Gs (Gs4 in the example shown) that is the target for obtaining each profile PF3, PF4, but does not include other rebar images Gs. Within this range R, the luminance profiles of multiple pixels aligned horizontally are obtained at the peak position Yp and the comparison position Yc to obtain each profile PF3, PF4. Note that range R can be set, for example, to a range of ±α (a predetermined value) based on peak position Xp.

5(b) and 5(c), the utility pole deterioration diagnosis device 13 calculates a first area Sa, which is a peak area of the deterioration portion luminance profile PF, and a second area Sb, which is a peak area of the comparison luminance profile PF4, and compares the areas Sa and Sb to estimate the rebar wall thickness remaining ratio D. In this embodiment, the rebar wall thickness remaining ratio D is determined by the following formula based on the ratio of the areas Sa and Sb.
D (%) = Sa/Sb × 100

The second area Sb may be any value that corresponds to the peak area of the luminance profile of the portion of the rebar that is not deteriorated, and may be, for example, a fixed value. The fixed value may be set, for example, by determining in advance, through experiments or simulations, the peak area of the comparative luminance profile PF4 that corresponds to a rebar in a healthy state.

The first area Sa, which is the peak area of the deterioration portion brightness profile PF, corresponds to the remaining wall thickness of the deteriorated portion of the reinforcing bar 22. Therefore, the utility pole deterioration diagnosis device 13 also executes a remaining wall thickness estimation process in the remaining wall thickness ratio estimation process.

The utility pole deterioration diagnosis device 13 calculates the remaining wall thickness ratio D for all reinforcing bars 22 that it determines to be deteriorated using the method described above. In addition, the utility pole deterioration diagnosis device 13 determines the remaining wall thickness ratio D to be 100% for reinforcing bars 22 that it determines to be healthy.

The evaluation process is a process of calculating a deterioration degree RT indicating the degree of deterioration of the reinforcing bar 22 based on the remaining wall ratio D estimated in the remaining wall ratio estimation process, and evaluating the utility pole 2 based on the deterioration degree RT. The deterioration degree RT may be a numerical value that increases as the degree of deterioration of the reinforcing bar 22 increases, and is calculated, for example, by the following formula.
RT (%) = 100-D

The utility pole deterioration diagnosis device 13 calculates the deterioration degree RT for each of the multiple reinforcing bars 22, and calculates the deterioration degree RP of the utility pole 2 using the following formula, thereby evaluating the utility pole 2.
RP = Σ(RTn×ln)
RTn: Degree of deterioration of each of n reinforcing bars 22 in a portion of the concrete column 21 where a tensile load is applied; ln: Distance from the nth reinforcing bar 22 in the portion where a tensile load is applied to the neutral plane

As shown in Figures 6(a) and 6(b), when wind pressure load is applied to the electric wires of the utility pole 2, a difference in the overhead line tension occurs, generating a bending load. When such bending loads occur repeatedly, cracks appear on the outer surface of the concrete pole 21 at the part where the tensile load is applied. As the cracks progress, rainwater etc. seeps into the concrete pole 21, and corrosion of the reinforcing bars 22 progresses.

On the other hand, the bending strength of the utility pole 2 is dominated by the reinforcing bar 22 on the tensile side of the utility pole cross section. In addition, when a bending load is applied to the utility pole 2, the tensile load applied to each of the multiple reinforcing bars 22 in the part of the concrete pole 21 where the tensile load is applied increases as the distance l from the neutral plane (L1) increases. Therefore, among the multiple reinforcing bars 22 in the part where the tensile load is applied, the strength deterioration of the reinforcing bar 22 located farthest from the neutral plane (L1) has the greatest effect on the decrease in the bending strength of the utility pole 2. Therefore, as in the above-mentioned formula RP = Σ (RTn × ln), the deterioration degree RP of the utility pole 2, which indicates the degree of decrease in the bending strength of the utility pole 2, can be accurately calculated by integrating the value obtained by multiplying the deterioration degree RTn of the reinforcing bar 22 by the distance ln from the reinforcing bar 22 to the neutral plane (L1).

In other words, it is possible to determine the deterioration of the bending strength of the utility pole 2 with respect to the load direction of the load applied to the utility pole 2. For example, by identifying the bending load, load direction, and the part to which the tensile load is applied due to the difference in overhead line tension when the design wind speed is applied to the utility pole 2 to be diagnosed, and calculating the aforementioned remaining wall thickness ratio D as the remaining cross-sectional strength of the part to which the tensile load is applied, detailed deterioration diagnosis is possible. It is also possible, for example, to arbitrarily set the load direction and diagnose the remaining utility pole bending strength for each load direction.

After completing the evaluation process, the utility pole deterioration diagnosis device 13 notifies the worker of the evaluation results by displaying the evaluation results on the screen 13A. Note that the notification method may be other methods, and for example, the evaluation results may be notified by voice.

The display on the screen 13A in each process of the utility pole deterioration diagnosis device 13 can be set arbitrarily. For example, in the rebar position identification process, the X-ray transmission image G shown in FIG. 3(a) and the position identification profile PF1 shown in FIG. 3(b) can be displayed on the screen 13A. Also, for example, in the rebar brightness acquisition process, the X-ray transmission image G shown in FIG. 4(a) and the rebar brightness profile PF2 shown in FIG. 4(b) can be displayed on the screen 13A. In this case, a vertical line L2 indicating the rebar position Xn corresponding to the rebar brightness profile PF2 can be displayed on the X-ray transmission image G.

For example, in the remaining wall ratio estimation process, the X-ray image G shown in FIG. 5(a) and the profiles PF3 and PF4 shown in FIGS. 5(b) and 5(c) can be displayed on the screen 13A. In this case, a vertical line L2 indicating the reinforcing bar position Xn, a horizontal line L3 indicating the peak position Yp, and a horizontal line L4 indicating the comparison position Yc can be displayed on the X-ray image G.

Next, the operation of the utility pole deterioration diagnosis device 13 will be described in detail with reference to FIG.
As shown in FIG. 7, when the utility pole deterioration diagnosis device 13 receives an instruction to execute image analysis, it first acquires an X-ray transmission image G from the imaging panel 12 (S1).

After step S1, the utility pole deterioration diagnosis device 13 obtains a position identification profile PF1 shown in FIG. 3(b) based on the X-ray transmission image G, and identifies reinforcing bar positions X1 to X8 for the multiple reinforcing bar images Gs1 to Gs8, respectively, based on the position identification profile PF1 (S2). After step S2, the utility pole deterioration diagnosis device 13 obtains a reinforcing bar brightness profile PF2 shown in FIG. 4(b) at reinforcing bar position Xn corresponding to one reinforcing bar image Gs (S3).

After step S3, the utility pole deterioration diagnosis device 13 determines whether or not there is a peak P11 in the reinforcing bar luminance profile PF2 (S4). If it is determined in step S4 that there is a peak P11 (Yes), the utility pole deterioration diagnosis device 13 determines that the reinforcing bar 22 is deteriorated, and identifies the peak position Yp and the comparison position Yc based on the reinforcing bar luminance profile PF2 (S5).

After step S5, the utility pole deterioration diagnosis device 13 acquires a deteriorated portion brightness profile PF3 at the peak position Yp (S6), as shown in FIG. 5. After step S6, the utility pole deterioration diagnosis device 13 acquires a comparison brightness profile PF4 at the comparison position Yc (S7).

After step S7, the utility pole deterioration diagnosis device 13 calculates a first area Sa, which is the peak area of the deterioration portion luminance profile PF, and a second area Sb, which is the peak area of the comparison luminance profile PF4 (S8). After step S8, the utility pole deterioration diagnosis device 13 calculates the deterioration degree RT based on the ratio between the first area Sa and the second area Sb (S9).

If it is determined in step S4 that there is no peak P11 (No), the utility pole deterioration diagnosis device 13 determines that the reinforcing bar 22 is sound (S12). After step S9 or step S12, the utility pole deterioration diagnosis device 13 determines whether deterioration judgment has been completed for all of the multiple reinforcing bar images Gs that are the subject of deterioration judgment (S10).

If it is determined in step S10 that the deterioration assessment has not been completed (No), the utility pole deterioration diagnosis device 13 returns to the processing of step S3. If it is determined in step S10 that the deterioration assessment has been completed (Yes), the utility pole deterioration diagnosis device 13 calculates the deterioration level RP of the utility pole 2 using the above-mentioned formula RP = Σ (RTn x ln). Then, based on the calculated deterioration level RP, the state of the utility pole 2 is evaluated, and this processing ends.

Next, a method for diagnosing deterioration of a utility pole will be described.
1 , the worker first identifies the portion of the utility pole 2 to which a tensile load is applied by, for example, cracks formed on the outer surface of the utility pole 2. Then, the worker positions the imaging panel 12 so that it faces the outer circumferential surface of the portion of the utility pole 2 to which the tensile load is applied. Next, the worker positions the X-ray irradiation device 11 on the opposite side of the imaging panel 12 with respect to the utility pole 2. Then, the worker places the first cover 14 over the X-ray irradiation device 11 and the second cover 15 over the imaging panel 12.

Then, the worker operates the X-ray irradiation device 11 to irradiate X-rays from the X-ray irradiation device 11, thereby acquiring, by the imaging panel 12, an X-ray transmission image G corresponding to the portion of the utility pole 2 to which the tensile load is applied (image acquisition process). Next, when the worker operates the utility pole deterioration diagnosis device 13 to input an instruction to start image analysis in the utility pole deterioration diagnosis device 13, the utility pole deterioration diagnosis device 13 analyzes the X-ray transmission image G and judges the deterioration of the reinforcing bar 22 (deterioration judgment process).

In the deterioration judgment process, the utility pole deterioration diagnosis device 13 identifies the reinforcing bar position Xn from the X-ray transmission image G (reinforcing bar position identification process) and acquires the reinforcing bar brightness profile PF2 at the reinforcing bar position Xn (reinforcing bar brightness acquisition process). After that, the utility pole deterioration diagnosis device 13 judges whether the reinforcing bar 22 is deteriorated or not by judging whether the reinforcing bar brightness profile PF2 has a peak P11 or not (judgment process). If it is judged that the reinforcing bar 22 is deteriorated in the judgment process, the utility pole deterioration diagnosis device 13 estimates the remaining wall thickness ratio D of the reinforcing bar 22 (reinforcing bar thickness estimation process). After the remaining wall thickness estimation process, the utility pole deterioration diagnosis device 13 calculates the deterioration degree RT of the reinforcing bar 22 based on the remaining wall thickness ratio D, calculates the deterioration degree RP of the utility pole 2 based on the deterioration degree RT, and evaluates the utility pole 2.

As described above, the following effects can be obtained in this embodiment.
Since the deteriorated portion of the reinforcing bar 22 is identified based on the brightness of the reinforcing bar image Gs and the remaining wall thickness of the reinforcing bar 22 is estimated based on the peak area of the deteriorated portion brightness profile PF3 in the image corresponding to the deteriorated portion, it is possible to diagnose the deterioration state of the reinforcing bar 22 in a short time with the smallest possible number of images, and to quantitatively evaluate the strength of the utility pole 2. The effects of this will be described in detail below.

As shown in FIG. 8(a), when one half of the reinforcing bar 22 is thinned, if an image is taken in a direction in which the outline 22A of the thinned portion overlaps the outline 22B of the non-thinned portion, the silhouette of the thinned reinforcing bar 22 (reinforcing bar image Gsa) may be the same as the silhouette of a normal reinforcing bar 22 (reinforcing bar image Gsb) as shown in FIG. 8(b). The reinforcing bar image Gsa corresponding to the thinned portion and the reinforcing bar image Gsb corresponding to the normal portion can be distinguished by the difference in shading, but depending on the degree of thinning, even an experienced person may have difficulty distinguishing between them. Therefore, in the conventional method of visually inspecting an X-ray transmission image to evaluate the deterioration of the reinforcing bar 22, it is necessary to take images from various angles to obtain a reinforcing bar image Gsa from which the outline 22A of the thinned portion can be obtained as shown in FIG. 8(d) and (e).

Since radiation is generated each time an X-ray image is taken, the risk of exposure increases as the number of images taken increases. In addition, depending on the amount of radiation generated, it may be necessary to set up a no-entry zone within a 5m radius of the X-ray source, making it difficult to carry out imaging examinations in residential areas with many utility poles or on busy streets.

In contrast, in the analysis method of this embodiment, a deteriorated portion brightness profile PF3 is obtained from the rebar image Gsa corresponding to the thinned portion, and a comparative brightness profile PF4 is obtained from the rebar image Gsb corresponding to the normal portion, so that when the rebar image Gs shown in Fig. 8(b) is obtained, profiles PF3 and PF4 as shown in Fig. 8(c) can be obtained, and when the rebar image Gs shown in Fig. 8(e) is obtained, profiles PF3 and PF4 as shown in Fig. 8(f) can be obtained. When the rebar image Gs shown in Fig. 8(b) is obtained and when the rebar image Gs shown in Fig. 8(e) is obtained, the waveforms of the deteriorated portion brightness profile PF3 are different, but the peak areas (Sa1, Sa2) are approximately the same. Therefore, in the analysis method of this embodiment, the peak area (Sa) of the deteriorated portion brightness profile PF3 is approximately the same regardless of the angle of the rebar image Gs, so the rebar 22 can be analyzed regardless of the direction from which the image is taken, and the amount of remaining material in the rebar 22 can be estimated regardless of the direction from which the X-ray image is taken. This analysis method has the advantage that the deterioration level (amount of remaining material) of the internal rebar can be calculated by taking an X-ray image from one direction, so the number of images taken is the minimum of one, and the radiation generated during the image taking is limited to only one image.

The rebar position Xn, which is the horizontal position of the rebar 22, is identified, and the rebar brightness profile PF2 is obtained at the identified rebar position Xn, so that it is possible to determine which of the multiple rebars 22 arranged horizontally are deteriorated.

The rebar position Xn is set to a position shifted from the lateral center of the rebar image Gs, so that the rebar luminance profile PF2 is obtained for the portion near the outer periphery of the rebar 22 where thinning occurs from the outer periphery side, and therefore the rebar luminance profile PF2 of the thinned portion can be obtained.

The remaining wall thickness ratio D of the reinforcing bar 22 is estimated by comparing the first area Sa, which is the peak area of the deteriorated portion luminance profile PF3, with the second area Sb, which corresponds to the peak area of the comparison luminance profile PF4, so that the remaining wall thickness ratio D of the reinforcing bar 22 can be estimated with high accuracy.

The present invention is not limited to the above-described embodiment, but can be used in various forms as exemplified below.
In the above embodiment, one reinforcing bar position Xn is set for one reinforcing bar image Gs, but the present invention is not limited to this, and multiple reinforcing bar positions Xn may be set for one reinforcing bar image Gs. For example, as shown in FIG. 9, three reinforcing bar positions X41 to X43 may be set for one fourth reinforcing bar image Gs4. In this case, a reinforcing bar luminance profile PF2 may be obtained for each of the reinforcing bar positions X41 to X43, and the deterioration of the reinforcing bar 22 may be determined by determining whether or not there is a peak P11 in at least one of the three reinforcing bar luminance profiles PF2. In addition, when there is a peak P11 in two or more reinforcing bar luminance profiles PF2, for example, the position of the peak P11 with the largest peak height among the multiple peaks P11 can be set as the peak position Yp.

In the above embodiment, the strength of the utility pole is evaluated using the degree of deterioration calculated based on the amount of remaining wall thickness, but the present invention is not limited to this, and the strength of the utility pole may be evaluated based on the amount of remaining wall thickness. Specifically, the remaining strength of the utility pole can be calculated from the remaining tensile strength related to the cross-sectional area of each reinforcing bar based on the amount of remaining wall thickness.

The elements described in the above embodiments and variations may be implemented in any combination.

2 Utility pole 11 X-ray irradiation device 12 Imaging panel 13 Utility pole deterioration diagnosis device 21 Concrete pole 22 Reinforcing bar G X-ray transmission image

Claims (8)

A utility pole deterioration diagnosis method for diagnosing deterioration of a utility pole having a cylindrical concrete pole and a plurality of reinforcing bars embedded in the concrete pole so as to be aligned in a circumferential direction, comprising:
an image acquiring process of arranging an X-ray irradiator facing an outer peripheral surface of the utility pole and arranging an imaging panel on the opposite side of the utility pole from the X-ray irradiator, and then irradiating X-rays from the X-ray irradiator to acquire an X-ray transmission image of a plurality of reinforcing bars arranged in a horizontal direction and extending in a vertical direction of the utility pole;
a remaining wall thickness estimation process for analyzing the X-ray transmission image by a utility pole deterioration diagnosis device, identifying deteriorated portions of the rebar based on the brightness of the rebar image, obtaining a deteriorated portion brightness profile which is a profile of the brightness of multiple pixels arranged horizontally in the image corresponding to the deteriorated portion, and estimating the remaining wall thickness of the rebar based on a peak area of the deteriorated portion brightness profile. Calculating a deterioration degree RT indicating a degree of deterioration of the reinforcing bar based on the remaining amount estimated in the remaining amount estimation step;
The deterioration degree of each of the n reinforcing bars in the portion of the concrete pole to which the tensile load is applied is defined as RTn, the distance from the nth reinforcing bar in the portion to which the tensile load is applied to the neutral plane is defined as ln, and the deterioration degree of the utility pole is defined as RP.
RP = Σ(RTn×ln)
The utility pole deterioration diagnosis method according to claim 1, characterized in that the deterioration degree RP of the utility pole is calculated by the above method and the utility pole is evaluated. The utility pole deterioration diagnosis method according to claim 1 or 2, characterized in that it includes a remaining wall ratio estimation process for estimating the remaining wall ratio of the rebar by comparing a first area, which is a peak area of the deteriorated portion brightness profile, with a second area corresponding to a peak area of the brightness profile of the portion where the rebar is not deteriorated. A reinforcing bar position identification process for identifying at least one reinforcing bar position Xn, which is a position of the reinforcing bar in a lateral direction, for each reinforcing bar image in the X-ray radiographic image;
A reinforcing bar brightness acquisition process for acquiring a reinforcing bar brightness profile, which is a profile of brightness of a plurality of pixels arranged vertically at a reinforcing bar position Xn of the X-ray radiographic image;
and a determination step of determining that the reinforcing bar corresponding to the reinforcing bar position Xn is deteriorated when a peak having a locally higher brightness than the surrounding area is detected in the reinforcing bar brightness profile,
Identifying a peak position Yp, which is a position in the vertical direction of the X-ray transmission image corresponding to a peak of the reinforcing bar brightness profile;
The utility pole deterioration diagnosis method according to claim 3, characterized in that the deteriorated portion luminance profile is acquired at a peak position Yp of the X-ray transmission image. In the reinforcing bar position identification process,
The utility pole deterioration diagnosis method described in claim 4, characterized in that a position identification profile, which is a profile of the brightness of multiple pixels arranged horizontally at at least one vertical position in the X-ray transmission image, is obtained, a peak position Xp where the brightness becomes small is detected in the position identification profile, and the reinforcing bar position Xn is identified based on the peak position Xp. The utility pole deterioration diagnosis method according to claim 5, characterized in that in the rebar position identification process, a position shifted from the lateral center of the rebar image is set as the rebar position Xn. In the remaining meat ratio estimation step,
determining a comparison position Yc, which is a position in the vertical direction of the X-ray transmission image away from a peak of the rebar brightness profile;
A comparative brightness profile is obtained at a comparison position Yc of the X-ray transmission image, which is a profile of brightness of a plurality of pixels arranged in a horizontal direction;
The utility pole deterioration diagnosis method according to any one of claims 4 to 6, characterized in that a peak area of the comparative luminance profile is calculated as the second area. A utility pole deterioration diagnosis system for diagnosing deterioration of a utility pole having a cylindrical concrete pole and a plurality of reinforcing bars embedded in the concrete pole so as to be aligned in a circumferential direction, comprising:
an X-ray irradiation device that irradiates X-rays;
an imaging panel that is disposed on the opposite side of the utility pole from the X-ray irradiation device and captures an X-ray transmission image of a plurality of reinforcing bars extending in the vertical direction of the utility pole arranged in the horizontal direction;
and a utility pole deterioration diagnosis device that analyzes the X-ray transmission image acquired by the imaging panel,
The utility pole deterioration diagnosis device is a utility pole deterioration diagnosis system characterized in that it identifies deteriorated parts of rebars based on the brightness of a rebar image, obtains a deteriorated part brightness profile which is a profile of the brightness of multiple pixels arranged horizontally in an image corresponding to the deteriorated part, and estimates the remaining amount of rebar based on a peak area of the deteriorated part brightness profile.

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