JP3133424B2 - Concrete structure deterioration inspection method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for inspecting the deterioration of a concrete structure such as a railway concrete bridge.

[0002]

2. Description of the Related Art Conventionally, a concrete structure is inspected for deterioration by taking an image of the concrete structure with an infrared sensor and displaying the surface temperature distribution of the concrete structure on a display in a color tone. In verification, a method of copying and copying the site is performed.

[0003]

However, the conventional method for inspecting the deterioration of concrete structures relies on the work of experts having many years of experience, so that a wide range of inspections cannot be performed in a short time. There was a problem.

An object of the present invention is to extract a deteriorated portion of a concrete structure from the output of an infrared sensor by data processing by a computer and display the image.

[0005]

As a means for solving the problems of the present invention, a method for inspecting deterioration of a concrete structure according to the present invention, as shown in FIG. The surface temperature distribution is detected by an infrared sensor, the temperature distribution of the concrete structure in a healthy state is simulated based on the specifications and conditions of the concrete structure, and based on the simulation result, the concrete structure detected above is detected. Calculate the unique temperature distribution that is different from the healthy state from the surface temperature distribution of
Based on the temperature distribution measurement data over the four seasons of a concrete structure similar to the concrete structure, extract a deteriorated portion of the concrete structure from the specific temperature distribution,
The gist is to display the deteriorated portion in correspondence with the image of the concrete structure.

[0006]

According to the concrete structure deterioration inspection method of the present invention, first, a specific temperature distribution which is a temperature distribution other than a sound state is calculated from a temperature distribution of a concrete structure taken by an infrared sensor and a simulation result.
Next, a deteriorated portion is extracted from the specific temperature distribution based on the temperature distribution measurement data of the concrete structure similar to the inspection object over the four seasons, and the deteriorated portion is displayed in association with the image of the concrete structure.

That is, an image output of the deteriorated portion can be obtained from the output of the infrared sensor.

[0008]

Next, an embodiment for detecting deterioration of a railway concrete structure by the method for inspecting deterioration of a concrete structure according to the present invention will be described. FIG. 2 is a block diagram illustrating a configuration of the concrete structure deterioration inspection device 1 according to the embodiment.

The concrete structure deterioration inspection apparatus 1 includes a lens 3, a scanner 5, a monitor television 7, a video tape recorder 9, a disc controller 11, and a data converter 1.
3, a floppy disk drive 15, a computer main body 17, a printer 19, a keyboard 21, a monitor television 23, and a character display 25.

The lens 3 is made of a germanium lens that transmits infrared rays, and is appropriately selected depending on the inspection target and the conditions at the site. The scanner 5 sends heat information from each point of the subject to an infrared detector through a high-speed rotation system to generate an electric signal for forming a thermal image. The lens 3 and the scanner 5 constitute an infrared sensor 6.

The monitor television 7 converts the electric signal output from the scanner 5 into density information for each pixel and outputs it as a thermal image. The video tape recorder 9 records the thermal image output from the monitor television 7. The disconnector 11 converts the signal level from the monitor television 7 from 0.7 VP-P to 1 VP-P.

The data converter 13 converts the thermal image recorded on the video tape recorder 9 into a floppy disk. The floppy disk drive 15 reads out a thermal image from the floppy disk. The computer main body 17 performs image processing of the thermal image input from the floppy disk. The printer 19 outputs an image displayed on the monitor television 23. The keyboard 21 controls image processing. The monitor television 23 reproduces an image or displays an image being processed. The character display 25 displays interactive information with the computer main body 17 using the keyboard 21.

FIG. 3 is a flowchart of a concrete structure deterioration inspection work process. An outline of the entire work will be described based on the flowchart of the concrete structure deterioration inspection work process. In the concrete structure deterioration inspection work process, first, a preliminary investigation is performed (Step 10, hereinafter, the steps are simply referred to as S). The preliminary survey investigates the structural type of the inspection target, the shooting location environment, the usage status, and the like. Next, shooting preparation is performed (S20). In the preparation for shooting, based on the results of the preliminary survey, the implementation items and the survey schedule are determined, and image data of the structure to be shot and temperature measurement data measured over the four seasons of concrete structures similar to the shooting target are prepared. Then, carry in, set, and adjust the equipment.

Next, photographing and recording are performed (S30). In the photographing recording, the infrared sensor 6 is adjusted based on a predetermined photographing standard, and processing for storing the photographed thermal image on a floppy disk is performed. After photographing and recording, computer image processing is performed (S40). In the computer image processing, a thermal image is read from a floppy disk, and the
Thus, the distortion, density, etc. of the thermal image are corrected.

After image processing by the computer, computer analysis is performed (S50). In the computer analysis, a deteriorated portion is extracted based on thermal image information after image processing and a simulation result of a healthy portion. After extracting the deteriorated portion, a deteriorated image is output (S60).

Next, the details of the concrete structure deterioration inspection will be described. FIG. 4 is a flowchart of photographing recording, FIG. 5 is an explanatory diagram of a photographing distance, FIG. 6 is an explanatory diagram of a photographing elevation angle, FIG. 7 is an explanatory diagram of a horizontal angle, and FIG.
In the photographing recording, the photographing target 27 is photographed by the infrared sensor 6 according to the photographing standards shown in FIGS. Here, shooting is performed according to the following shooting standard.

1. Photographing distance The distance between the photographing target 27 and the infrared sensor 6 varies depending on the focal length of the mounting lens 3, but the positional relation is such that the area of the photographing target 27 is within 6 square meters. or,
The entire surface of the object to be photographed 27 is set to have two to four photographing screens. It should be noted that two types of images are taken, the whole one and the divided one.

2. Imaging Elevation Angle and Horizontal Angle When imaging a high imaging object 27 or a large imaging object 27, the elevation angle and the horizontal angle should be within 45 degrees at the maximum. 3. Divisional Shooting Method After satisfying the above-described shooting standards 1 and 2, the lens 3 is focused and each adjustment is performed. Next, monitor TV 7
While looking at the screen, the infrared sensor 6 is slowly raised to the uppermost portion, and it is confirmed whether or not there is a color portion (a density portion in the case of monochrome) indicating that the temperature is outside the predetermined temperature range on the image. If there is a portion outside the predetermined temperature range, the controller of the infrared sensor 6 is readjusted so that the entire surface is within the predetermined temperature range. Thereafter, as shown in FIG. 8, images are repeatedly photographed sequentially from the screen range.
Note that the picture mode of the infrared sensor 6 is set to invert during daytime shooting, and to normal during nighttime shooting. In addition, high-temperature parts (daytime) and low-temperature parts (nighttime), which are presumed to be voids in concrete and peeling parts of the exterior
Is the same color (density) heat distribution (black part is void / peeled part)
And

The photographing is started with the photographing conditions satisfying the photographing standards 1 to 3 prepared (S100). When a photograph is recorded along with this photographing (S11
0), a photograph is taken of the photographing range by the infrared sensor 6 with the instant camera (S120). Next, the thermal image on the monitor television 7 is recorded on the digital tape of the video tape recorder 9 (S130), and predetermined photographing conditions are recorded (S140). After the end of these operations in S100 to S140, the next photographing range is photographed. As a result, a thermal image of the photographing object 27, that is, data of the temperature distribution is recorded by the video tape recorder 9. The data of the temperature distribution is stored in the floppy disk by the disc 11 and the data converter 13.

Next, a process of extracting a deteriorated portion from the data of the temperature distribution stored in the floppy disk and printing it out will be described. FIG. 9 is a flowchart of the computer image processing / analysis processing. In the computer image processing / analysis, first, an infrared sensor thermal image is input (S200). Here, the contents of the floppy disk are read from the floppy disk drive 15 and
The video data is input to the video memory of the computer main body 17 and displayed on the monitor television 23. Next, image processing is performed (S210). In the image processing, patchwork processing, geometric correction, distortion correction, density correction, and image enhancement are performed.

In the patchwork process, the thermal image data of the photographing object 27 divided and read is joined one by one on the display screen of the monitor television 23 as shown in FIG. 10, and as shown in FIG. This is for creating a survey photographing target plane image 29. The geometric correction is performed because the imaging of the imaging target 27 is performed with a wide imaging range as illustrated in FIGS. 5 to 7. Since the shooting distance is changed due to a change in infrared intensity and the angle of view of the shooting is changed, an image taken in an oblique direction as shown in FIG. 6 and FIG. This is performed in order to enable a superimposition process with a plan view or the like in advance. In this processing, enlargement and reduction are performed.

The distortion correction corrects the noise of the device and the optical distortion of the lens. The density correction is for correcting attenuation and heat reflection of the atmosphere, density changes after patchwork, and the like. The image enhancement is for enhancing the image contrast.

Next, visual noise removal is performed (S
220). Noise removal is erroneously recognized as noise peculiar to railway concrete structures, such as the presence of railway tracks and ballasts on top of concrete structures, and noise peculiar to structural features, such as voids and cracks. This is to remove the noise that is caused by the noise and refer to the temperature distribution measurement data over the four seasons measured for each type and shape of the railway concrete structure, etc., and monitor according to the actual condition of the concrete structure. This is to remove noise from the thermal image on the screen of the television 23.

Various parameters are input in parallel with the above-described image processing (S300). In the parameter input, the file name of the image data, the outside air temperature, the shooting distance, the thickness of the structural material to be shot, the thermal conductivity of the concrete material, the specific heat, the thermal diffusivity, the infrared emissivity, and the interface heat Input the transmission rate and the shooting elevation angle. The data relating to the specifications of the railway concrete structure is registered for each type of the structure and input collectively.

After the input of the parameters, the simulation of the surface temperature distribution in the normal state is performed (S310). The simulation of the surface temperature distribution in the normal state is performed by a calculation program created in advance by the following method. The surface temperature of the concrete wall surface is determined by internal conditions and external conditions.

The internal condition is a condition on the structure side, and the external condition is a photographing time zone, a season,
Refers to the weather environment such as the weather. The surface temperature is obtained by a statistical investigation of a known wall surface and a thermal analysis by an unsteady thermal analysis (finite element method).

The surface temperature distribution on the wall surface varies greatly depending on the structure of the wall surface itself and the surrounding environment. On the other hand, it is extremely difficult to accurately measure the surface temperature distribution of an object. Fortunately, the heat behavior can be calculated with high accuracy, and thus the heat conduction analysis using the finite element method can be performed.

Reference Example of Thermal Analysis The structure is a concrete wall having the internal conditions shown in FIG. The external conditions are (1) the temperature on both sides of the concrete wall, (2) the height of the concrete wall from the ground or floor, the wind speed, the unevenness of the surface, the inclination, and (3) the generation of heat by sunlight.

Analysis of heat conduction in concrete wall The basic equation of the finite element method is as shown in the following equation (1).

[0030]

(Equation 1)

Heat conduction model Inside the wall surface: Heat conduction Between the wall surface and convective air: Convection heat transfer Q Q = a (Ta−T0) a: Heat transfer coefficient Ta: Concrete surface temperature .

U: Wind speed L: Height from floor or ground (Numerical calculation) Simulation setting * Equation As shown in equation (3).

[0033]

(Equation 2)

The empirical formula of the heat transfer coefficient a of the vertical wall surface of the concrete used the formula (4). L = 5m, U = 4m / s
In the case of ec, a becomes the equation (5), and L = 1 <U = 0
In the case of, a is given by equation (6). * The generation of heat by the sun is as shown in equation (7).

* Physical constants are as shown in Table 1.

[0036]

[Table 1]

* Calculation conditions Temperature inside concrete wall changes by 10-30 ° C Temperature outside concrete wall changes by 10-35 ° C Internal temperature T (t) = Acos (Bt) + C External temperature T (t) = Acos (Bt) + C The heat transfer coefficient (external) is as shown in equation (8), and the heat transfer coefficient (internal) is as shown in equation (9).

The size of the deteriorated portion (void) of the concrete is 5 mm or more. 13 and 14 show graphs of the analysis results. As shown in FIGS. 13 and 14, during the daytime (12:00)
Has a concrete outer surface temperature of 27.1 ° C. in a healthy part. Note that this is a theoretical value and is actually + 0.6 ° C. under the above conditions, and the surface temperature of the healthy portion of the concrete is 27.7 ° C.

Therefore, based on the analysis results, a portion at 27.8 ° C. or higher on the thermal image of the infrared sensor 6 surveyed and photographed at 12:00 is determined to be a concrete deteriorated portion (gap portion).
In addition, the analysis of the depth of the deteriorated portion of the concrete (void) can be calculated by calculating the thermal resistance of the concrete based on the surface temperature (27.8 ° C.). That is, in order to generate a temperature difference of 2.7 ° C. between the sound portion and the deteriorated portion of the concrete, the thickness (thermal resistance value) of the concrete is analyzed to determine the thickness. (Because the effect of temperature change due to the thickness of the air gap cannot be ignored, the calculated value will have some errors.) The calculation program for each type of railway concrete structure created based on the above-described method, Is simulated.

After completion of both the image processing (S210) and the simulation (S310), image analysis is performed (S400). In the image analysis, a thermal image difference process, a region division process, a feature extraction process, and a ternarization process are performed.
The thermal image difference process is a process of subtracting a simulation value of a healthy part, which is a reference temperature, from a patchwork or a corrected thermal image by image processing. As a result, a specific temperature distribution image (an image obtained by subtracting the healthy state temperature value from the temperature value of the thermal image) can be obtained from the thermal image.

The region dividing process is a process of dividing a high-temperature portion and a low-temperature portion from a specific temperature distribution image. Thereby, a high-temperature side image and a low-temperature side image of a high temperature portion with respect to the reference temperature are obtained. The feature extraction process is a process of extracting a degraded portion based on the high-temperature side image and the low-temperature side image, and extracts the degraded portion by the following method.

When there are voids inside the concrete structure, the surface temperature changes as compared with the normal state, as shown in the heat reflux diagram in FIG. For example, if it is 12:00, 2.
The temperature rises by 7 ° C. and decreases by α ° C. at 24:00. That is, as shown in FIG. 13, for example, the healthy part and the deteriorated part have a deviation in the surface temperature according to the change in the outside air temperature.

As shown in these figures, in the daytime, the deteriorated portion has a higher temperature than the healthy portion, and at night, the deteriorated portion has a lower temperature than the healthy portion. Therefore, when photographed in the daytime, the high-temperature side image becomes an image with a rough deterioration distribution as it is when photographed in the nighttime.

When there is dirt on the wall surface, as shown in FIG. 15, since the surface temperature rises due to dirt, it is necessary to correct the high-temperature side image and the low-temperature side image. In other words, as shown in FIG.
The surface temperature of the healthy portion increases during the daytime and decreases at night, but the dirty portion is observed at a higher surface temperature than the healthy portion even at night. Therefore, if the wall surface is dirty, this portion is visually checked and corrected, or the nighttime surface temperature is detected and the dirty portion is removed to detect and correct the deteriorated portion. Will be

Also, concrete structures such as railway bridges are different from vertical walls such as building outer walls and dams in that the photographing target wall does not have a temperature difference of 5 ° C. to 10 ° C. or more between day and night, and is sound. The temperature difference between the surface of the portion and the deteriorated portion does not exceed 1.0 ° C. That is, for example, sunlight does not directly shine on the underside of the floor slab of a railway bridge, so the temperature difference between the surface of the deteriorated part and the healthy part is as small as about 0.1 ° C. to 0.5 ° C. Therefore, when extracting a deteriorated part from the high-temperature side image or the low-temperature side image described above, based on the temperature distribution measurement data over the four seasons, this temperature difference is estimated according to the current environment and temperature, and the deteriorated part is determined. Extract. For example, when it is certain that the temperature difference of the deteriorated portion exceeds 0.1 ° C., the threshold value is set to 0.1 ° C., and all the portions having the temperature difference larger than this are extracted as the deteriorated portion.

In the ternarization processing, a ternary image of a deteriorated part, a healthy part, and an unknown part is generated. After the image analysis, a deteriorated portion extracted image is output (S410). In the output of the deteriorated portion extracted image, the ternary image generated by the ternarization process is combined with the image of the photographing target 27, and an image as shown in FIG.

The image of the photographing object 27 is stored in advance for each type of the railway concrete structure, and is read and used. In addition, upon display, based on the ternary image, a peeling degree, a peeling position (a position on a plane and a depth),
As shown in FIG. 16, the four corners corresponding to the degree of peeling (A) are displayed at the position where the deterioration occurs, and the peeling area (B) and the peeling position (u, a) are displayed. I do.

If it is not clear whether or not the image has deteriorated, the image of that part in the ternary image is displayed as it is. After outputting the image to the monitor television 23, the image is output to the printer 19 and printed (S420).

In this embodiment, the description has been given of the voids. However, the present invention is not limited to the voids, and it is possible to detect floating, cavities, water content, cracks, and the like of concrete by substantially the same principle. As described above, the concrete structure deterioration inspection apparatus 1 of this embodiment captures the railway concrete structure with the infrared sensor 6 and sequentially executes a predetermined process to extract a deteriorated portion, display, And printing is performed. Therefore, experienced technicians can
Since there is no need to judge the deteriorated portion and sketch, the deterioration can be detected by any engineer who has received a predetermined education. That is, a skilled engineer is not required. In addition, since the infrared sensor is used instead of the visual inspection and the calculation is mostly performed by a computer, the following effects can be obtained. Easy operation and high mobility. No scaffolding is required and efficient testing is possible. The degree of prevention of oversight is higher than visual observation. It is not restricted by roads, rivers, bridges, etc. With the performance of the current infrared sensor, a subject distance of 150 m is possible. The determination can be standardized and efficient. Data can be stored, and aging can be confirmed.

Further, based on the current performance of the infrared sensor 6 and the performance of the computer, a process for removing noise that is erroneously recognized as deterioration from the thermal image based on the temperature distribution measurement data over the four seasons, Based on the distribution measurement data, we added processing to make various corrections.
As described below, an effect suitable for detecting deterioration of a railway concrete structure can be obtained.

1. It can be analyzed throughout the four seasons.
This is suitable for railway applications that require constant maintenance work. 2. It is possible to combine and display the deteriorated portion with the figure of the structure. As a result, on-site confirmation can be quickly performed.

3. Crack deformation extraction can be performed even in the shaded area at 3 mm or more. 4. The cavity deformation depth inside the concrete can be detected up to about 100 mm. 5. Since railway bridges are almost formalized, it is possible to record measurement data for each type one after another to improve the analysis accuracy.

[0053]

According to the method for inspecting deterioration of a concrete structure of the present invention, a specific temperature distribution which is a temperature distribution other than a sound state is calculated from a temperature distribution of a concrete structure photographed by an infrared sensor and a simulation result. Based on the temperature distribution measurement data of the concrete structure similar to the object over the four seasons, a deteriorated portion is extracted from the unique temperature distribution and displayed in association with the image of the concrete structure.

Therefore, a skilled technician can
Since there is no need to judge the deteriorated portion and sketch, the deterioration can be detected by any engineer who has received a predetermined education. That is, a skilled engineer is not required. In addition, since it is configured to extract the deteriorated part based on the temperature distribution measurement data over the four seasons, by preparing the temperature distribution measurement data having conditions similar to the measurement target, various seasons, time zones, And the structure.

[Brief description of the drawings]

FIG. 1 is a flowchart illustrating a basic configuration of a concrete structure deterioration inspection method of the present invention.

FIG. 2 is a configuration diagram of a concrete structure deterioration inspection apparatus according to an embodiment.

FIG. 3 is a flowchart of a concrete structure deterioration inspection work process.

FIG. 4 is a flowchart of shooting and recording.

FIG. 5 is an explanatory diagram of a photographing method of the infrared sensor 6.

FIG. 6 is an explanatory diagram of a photographing method of the infrared sensor 6.

FIG. 7 is an explanatory diagram of a photographing method of the infrared sensor 6.

FIG. 8 is an explanatory diagram of a photographing method of the infrared sensor 6.

FIG. 9 is a flowchart of computer image processing and analysis processing.

FIG. 10 is an explanatory diagram of image processing.

FIG. 11 is an explanatory diagram of image processing.

FIG. 12 is an explanatory diagram of image analysis.

FIG. 13 is an explanatory diagram of image analysis.

FIG. 14 is an explanatory diagram of image analysis.

FIG. 15 is an explanatory diagram of image analysis.

FIG. 16 is an explanatory diagram of image analysis.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Concrete structure deterioration inspection apparatus, 3 ... Lens, 5 ... Scanner, 6 ... Infrared sensor, 7 ... Monitor television, 9 ... Video tape recorder, 11 ... Discon , 13: Data conversion, 15: Floppy disk drive, 17: Computer body, 19: Printer, 21: Keyboard, 23: Monitor television, 25: Character display, 27・ ・ ・ Target object, 29 ・ ・ ・ Survey target image,

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Naoyuki Nishi 2-4-5 Minamishinagawa, Shinagawa-ku, Tokyo Inside Pony Atomic Industry Co., Ltd. (56) References JP-A-1-182714 (JP, A) JP-A-63-140945 (JP, A) JP-A-62-212779 (JP, A) JP-A-62-172249 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G06T 1 / 00 G06T 7/00-7/60 G01N 21/84-21/958

Claims (1)

(57) [Claims] 1. A surface temperature distribution of a concrete structure such as a railway concrete bridge is detected by an infrared sensor, and a temperature distribution of a healthy state of the concrete structure is simulated based on the specifications and conditions of the concrete structure. Based on the simulation result, a specific temperature distribution different from a healthy state is calculated from the detected surface temperature distribution of the concrete structure, and the temperature distribution measurement data of the concrete structure similar to the concrete structure over four seasons is calculated. A concrete structure deterioration inspection method, wherein a deteriorated portion of a concrete structure is extracted from the specific temperature distribution based on the specific temperature distribution, and the deteriorated portion is displayed in correspondence with an image of the concrete structure.