JPH09145648A - Method of detecting defects in structures - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the accuracy of judgment by measuring by an infrared radiation thermometer the surface temperature of a structure within a period from a specified time in one day when it is fine in the day time to a specified time in the following day and judging whether or not the difference between the obtained result and that in its peripheral area is a specified value or higher and adopting the lower value to detect defects. SOLUTION: Infrared radiation thermometers 2A to 2D are fitted on the respective surfaces of outer walls of a building 1 to be detected. The detection signals obtained by the thermometers 2A to 2D are inputted into an image analyzer 10. The analyzer 10 obtains temperatures and temperature distribution within a range of objective picked-up image. The images in a time period from 19:00 in one day when it is fine in the day time to 4:30 in the following day are fetched, and an area whose surface temperature is at least 0.3 deg.C lower than that of its peripheral area is judged to include any defect.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting a defect in an outdoor structure such as a building, and more particularly to a method for detecting a defect in a structure for detecting rising of tiles or mortar.

[0002]

2. Description of the Related Art When a crack is generated on an outer wall or a tile is raised due to long-term use of a structure,
Risk of water leakage and flaking of exterior walls or tiles.

Therefore, conventionally, in order to detect these, there has been known a method in which an operator makes a judgment by hitting the surface with a wooden hammer or the like and making a sound.

However, this not only results in poor workability, but also lacks reliability.

Therefore, a method of detecting a defect having excellent workability and high reliability has been sought. One of them is a method of detecting radiant energy from the surface of a structure with an infrared radiation thermometer and detecting a portion where the temperature difference is high to detect the presence or absence of a defect or the location of the structure.

[0006]

It is known that this method is basically an excellent method, and various proposals have been made for its improvement. However, the method does not surround the actual structure. Despite the wide variety of environments, appropriate conditions have not always been clarified, and it has been common knowledge that defects are detected during the day.

However, during the daytime, the amount of solar radiation, the shadow on the structure to be detected, or the ambient temperature or other disturbances are easily affected, and these disturbances cause measurement errors, so that the defect-free portion is erroneously repaired. Sometimes it was peeled off.

In addition, conventionally, since the defect is determined based on the temperature measurement result only once during the daytime, the above problem becomes more remarkable because it is more susceptible to the influence of disturbance. Further, conventionally, a defect is estimated based on a color difference of an infrared image, but a qualitative determination based on a color difference has an individual difference of an inspector, which causes an erroneous determination of the defect.

Therefore, an object of the present invention is to reliably detect defects in a structure, and in particular to increase the accuracy rate of defect determination.

[0010]

The invention according to claim 1 which has solved the above-mentioned problems, is a method for detecting a defect of a structure by detecting radiant energy from the surface of an outdoor structure by an infrared radiation thermometer, At least on the day when there was fine weather during the day, from 19:00 on that day to 4:
Within 30 hours, the surface temperature of the structure was measured by the infrared radiation thermometer, and the temperature difference with the surroundings was 0.3 ° C.
The above is the method for detecting defects in a structure, which is characterized in that it is determined that there is a defect in a gutter region having a low temperature.

A second aspect for further enhancing the accuracy of defect determination.
In the invention described in (1), the surface temperature of the structure is measured at least once in the daytime and at least once in the time zone, and the defects are comprehensively determined based on the surface temperature measurement results of both.

Further, according to the invention described in claim 3,
The structure surface temperature is detected also in the daytime of the day, and the temperature difference between the structure surface temperature in this daytime and the nighttime time zone is + 0.3 ° C. or more in the daytime, and − at night.
It is preferable to determine that there is a defect in a region of 0.3 ° C. or higher.

From the results of various experiments described below, the present inventor
The following points were obtained.

(1) During the daytime, changes in the amount of solar radiation, the presence or absence of shadows on the outdoor structure to be detected, the outside temperature, etc. act as disturbances. That is, as shown in FIG. 9, the amount of solar radiation shows a large change in a relatively short time on each of the north, south, east, and west faces. Moreover, the position of clouds and the position of shadows of other structures also have an effect. Further, as shown in FIG. 10, the fluctuation of the ambient outside temperature is large (the temperature may temporarily drop due to the influence of rainfall or wind).

As a result, the surface temperature of the outdoor structure slightly changes in a short time. Due to the large change in the surface temperature with time, the variation in the temperature difference between the defective portion and the non-defective portion also becomes large. Therefore, during the daytime, it may cause disturbance such as the amount of solar radiation and cause the defect portion to be erroneously determined.

(2) However, according to the present invention, at least on a day when there is fine weather,
If the temperature is detected within the time from 9:00 to 4:30 on the next day, the defect can be accurately detected with almost no influence of disturbance.

During the daytime, the temperature of the surface of the structure rises due to solar radiation. A part of the solar energy projected on the surface is reflected, but the rest is absorbed in the area, and the absorbed thermal energy is eventually transferred to the wall thickness direction. The surface temperature of the structure is determined by the relationship between this heat energy and its heat transfer rate. However, if there is a defective portion, such as a floating tile, heat transfer is hindered in that floating portion, and the transfer of absorbed heat energy is slowed down. Get higher.

At night, heat transfer in the opposite direction occurs in which the heat energy absorbed by the structure is dissipated to the outside air having a low temperature. Therefore, the temperature of the surface of the structure is low,
High internal temperature causes reversal phenomenon. Under this reversal phenomenon, the temperature difference between the defective portion and the non-defective portion also causes a "temperature reversal phenomenon" in which the temperature of the non-defective portion is lower than that of the defective portion. It is considered that this is because there is no factor that hinders heat transfer such as floating in the wall thickness direction in the defect-free portion, and thus the heat transfer rate from the inside of the structure to the outside air is high.

Considering the difference between the temperature difference between the defective portion and the non-defect portion during the daytime and the temperature difference during the nighttime, the above-mentioned solar radiation situation during the daytime at nighttime,
There are almost no disturbance elements such as the presence or absence of shadows, and it mainly depends on the speed at which the heat energy absorbed by the structure is dissipated to the outside air having a low temperature. Therefore, it is considered that the change over time in the temperature difference under the above-mentioned “inversion phenomenon of the temperature difference” is small.

In fact, as shown in an embodiment described later, the correct answer rate for determining a defective portion is higher at night than during daytime.

On the other hand, when there is no fine weather in the daytime, and in the case of rain or cloudy weather, the heat energy absorbed inside the structure is small, so that the amount of the heat energy emitted to the outside air is small at night. Moreover, an error is likely to occur in the defect determination. Further, the temperature difference between the adjacent unit areas is 0.
The fact that the portion where the temperature is lower than 3 ° C. is used as the basis for the defect determination also causes an error in the defect determination.

(3) On the other hand, in the conventional example, the defect was judged based on the measurement result of only one time during the day.

On the other hand, according to the present invention, it is desirable to perform the measurement during the nighttime time zone as described above. In order to improve the accuracy of the defect determination, it is more preferable to perform the measurement a plurality of times in the nighttime time zone and perform the defect determination comprehensively.

Further, as can be seen from the result of the time-series change of the temperature, which will be described later, the temperature difference change is generally larger in the daytime than in the nighttime. So at least once during the day,
It is possible to measure the surface temperature of the structure at least once in the time zone and comprehensively determine the defects based on the surface temperature measurement results of both.

Further, the structure surface temperature is detected also in the daytime of the day, and the temperature difference between the structure surface temperature during the daytime and the nighttime time zone is + 0.3 ° C. or more in the daytime and at nighttime. It is preferable to determine that there is a defect in a region of −0.3 ° C. or higher.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be specifically described below. The basic defect detection method of the present invention is provided with an infrared radiation thermometer (thermal image detector) by staring at the surface of a target structure, and infrared radiation energy from each surface is detected by the infrared radiation thermometer. Then, this detection signal is taken into the image analysis device, and the temperature and temperature distribution within the target imaging range are obtained in this image analysis device.

Under this information, the temperature difference from the surroundings is 0.3.
It is determined that there is a defect in the crease region of not less than 0 ° C and the temperature is low.

Further, in the present invention, at least on a day when there is fine weather, 19:
The thermal image is captured within the time from 00 to 4:30 on the next day, the temperature difference from the surroundings is 0.3 ° C. or more, and
Although the temperature is low, it is determined that there is a defect in the area of the wax.

In the present invention, the limitation on the time zone for capturing the thermal image and the temperature difference are made clear by the experiments described in detail below.

(Basic Experiment) As shown in FIG. 1, each structure has a width of 5 m and a height of 1.8 m on the roof of an existing structure 10 in a local city as a structure to be detected. A model building 1 with new edge tiles attached was constructed. As shown in FIG. 2, the outer wall 1 on the east side of this model building 1
On each surface of A, the outer wall 1B on the south side, the outer wall 1C on the west side, and the outer wall 1D on the north side, a simulated defect portion (tile peeling defect portion and mortar peeling defect portion in half) was artificially formed in an area of about 7%. Here, assuming that the simulated defect portion also determines whether or not there is a difference due to the area of the defect region, the tile peeling defect portion and the mortar peeling defect portion each have an area for 32 sheets and an area for 16 sheets. A region, a region for 8 sheets, and a region for 4 sheets were formed. The area value of 7% is an average value of the actual situation when the tile defect portion investigation is requested.

In order to detect the defects on the outer wall surfaces, infrared radiation thermometers (thermal image detectors) 2A, 2B, 2C and 2D that gaze at the outer wall surfaces were installed on the rooftop.

The detection signals from the infrared radiation thermometers 2A to 2D are input to the image analysis device 10, and the analysis signal is displayed on the CRT display device 11 or the like or recorded on a flexible disk or the like.

In the apparatus constructed as described above, the infrared radiation energies from the outer walls 1A to 1D are detected by the infrared radiation thermometers 2A to 2D, respectively. Then, the average temperature per each unit area arbitrarily divided is obtained, and the presence or absence of a defect is determined based on the temperature difference between adjacent unit areas.

In the experiment, on a sunny day in spring, the infrared radiation thermometer continuously measured at intervals of 10 minutes for about 25 hours from the sunrise. At the same time, the outside air temperature and the amount of solar radiation were measured.

FIG. 3 shows the surface temperature change of the tile peeling defect portion in the area corresponding to 16 tiles on the east surface, FIG. 4 shows the surface temperature change of the mortar peeling defect portion in the area corresponding to 16 tiles on the east surface, and FIG. The change in the amount of solar radiation with respect to, and the change in the outside air temperature are shown in FIG. On the east side, the surface temperature changes in the respective defect parts (regions per 32 tiles to region of 4 tiles) were substantially the same (however, regarding the temperature difference described later, the larger the area of the defect part, the larger the area size). , And the rate of increase and decrease in temperature difference tends to be slightly faster over time).
Therefore, it has been clarified that such a temperature (time-dependent) change shows a similar surface temperature change regardless of the area of the defect region in the experiment. This is the same for the other three surfaces, although the results are not shown.

Therefore, the results of the defective portion in the area corresponding to 16 tiles will be shown below as a representative.

On the east side, as shown in FIG. 5, since the amount of solar radiation in the morning is large, as shown in FIGS. 3 and 4, the surface temperature of the defect reaches its peak in the morning until noon. Shows a considerable temperature drop. This rate of temperature decrease is extremely slow in the evening, but shows a moderate decrease until near sunrise.

FIGS. 7 and 8 show the temperature difference between the tile peeling defect portion and the defect-free portion and the temperature difference between the mortar peeling defect portion and the defect-free portion with respect to this surface temperature change.
It is.

Looking at the results of the time-dependent change in the temperature difference of the tile peeling defect portion in FIG. 7, the defect temperature portion shows a positive temperature difference higher than that of the non-defect portion from around 6 am. After that, the peak of the temperature difference was shown, followed by 9 before noon.
After the hour, the temperature difference becomes close to zero, and thereafter, the temperature difference becomes negative until about 4 pm, causing a "temperature reversal phenomenon".
After that, at about 6 pm, the "reverse phenomenon of temperature difference" occurred again.
Occurs and is maintained until sunrise.

Looking at the results of the change in temperature difference with time for the mortar peeling defect portion in FIG. 8, the defect portion shows a positive temperature difference having a higher temperature difference than the non-defect portion from about 6 am,
After that, the temperature difference peaks, and then at about 10 o'clock before noon, the temperature difference becomes close to zero, and a "temperature difference inversion phenomenon" occurs in which the temperature difference becomes negative, and this is maintained until near sunrise.

According to the results of FIG. 7 and FIG. 8 only, in the eastern surface, the time zone in which the temperature difference is large with respect to the tile peeling defect portion and the mortar peeling defect portion is almost the same, and from 6 am to 6 am It turns out that it is 9am. The time zone where the temperature difference is large almost coincides with the time zone where the amount of solar radiation is large. However, it does not match the outside temperature. On the other hand, even at night, there is a relatively large temperature difference despite the occurrence of the "inversion phenomenon of the temperature difference".
It is also understood that it will be maintained from 9:00 to 4:30 the next day.

The results of FIGS. 7 and 8 above are changes in temperature difference for the eastern surface.

On the same day as the test, however, the change in temperature difference between the mortar peeling defect portion on the other south, west, and north surfaces was examined, and the results shown in FIGS. 9 to 11 were obtained.

According to these results, it can be seen that the time zone showing a positive temperature difference during the day is greatly deviated particularly in the south and west faces as compared with the east face. Also, it can be seen that it is difficult for a large temperature difference to appear on the north side.

On the other hand, it can be seen that at night, a relatively large temperature difference is stably shown on any surface. Especially on the north side, the negative temperature difference at night is larger than the positive temperature difference during the day.

The above results are observations in spring. On the other hand, the same experiment was conducted in the summer season.
12 to 1 show the results of the temperature difference changes on the east surface, the south surface, and the west surface of the mortar peeling defect portion, respectively.
It is shown in FIG.

Although the individual results of these summers are not described in detail, they show the same tendency as the results of spring. It has been confirmed that the trend does not change even in the autumn and winter.

As is clear from the above series of explanations, during the daytime, although there are time zones specific to each outer wall surface that exhibit a large temperature difference, the change in temperature difference within that time zone is relatively large. Although it is unstable, it shows a relatively large temperature difference and is stable regardless of the season, especially at night, especially from 19:00 to 4:30 on the next day. I understand.

(Percentage of Correct Answers for Defect Judgment) In the spring, the tile peeling defect portion and the mortar peeling defect portion each have a large temperature difference unique to each outer wall surface during the day, and on the day that is uniformly determined. In the time zone from 19:00 to 4:30 on the next day, the temperature difference is 0.
A portion having a temperature of 3 ° C. or higher was determined as a defective portion.

Considering the correspondence between this judgment result and the simulated defective portion in the actual model building, and when the correct answer is given only when it corresponds to the reality, the results are shown in Tables 1 to 4. It was In this case, the correct answer rate was calculated for each area corresponding to the number of tiles.

Table 1 shows the correct rate of tile peeling defects during the day, Table 2 shows the correct rate of tile peeling defects during the night, Table 3 shows the correct rate of mortar peeling defects during the day, and Table 4 shows. The accuracy rate of the mortar peeling defect part at night is shown respectively.

[0052]

[Table 1]

[0053]

[Table 2]

[0054]

[Table 3]

[0055]

[Table 4]

From Tables 1 to 4, when the number of peeled tiles required to repair the peeled tiles was four or more, the western surface was not reflected at all when peeling the tiles. It was as low as 8%. On the other hand, 79.6% at night
And showed a high number. In the case of mortar peeling, it was 81.7% during the day, but 100% at night.
% And the highest number was shown.

When the results are summarized, it can be seen that the mortar peeling defect portion is easier to detect than the tile peeling defect portion, and the defect detection determination is more accurate at night than at daytime.

Experiments similar to those described above were conducted in summer and autumn. The summer experiment day was fine, but the fall experiment day was cloudy.

The correct answer rate in the result of the summer experiment was 80.0% in the day and 8 in the night for the tile peeling defect portion.
1.3%. The mortar peeling defect portion was 91.7% in the daytime and 96.7% in the nighttime. From these results, it was found that the mortar peeling defect portion is easier to detect the defect than the tile peeling defect portion, and the defect is easier to detect at the night time than in the daytime.

On the other hand, the correct answer rate in the defect of the autumn experiment is
For tile peeling defect part, 73.3% during the day, 4 at night
It was 8.8%. The mortar peeling defect portion was 90.8% in the daytime and 75.8% in the nighttime. The low accuracy rate at night in this experiment is due to the fact that the amount of heat stored was small and there was no temperature difference because there was no solar radiation during the day. Therefore, it turns out that it is necessary to avoid cloudy or rainy days throughout the day.

The present invention can be used not only for the diagnosis of the outer wall of the building described above, but also for the diagnosis of roofs, chimneys, dams, embankments, bridges, roads (overpasses) and the like. Further, cracks, peeling, lifting, and the like can be detected as the property of the defect.

[0062]

As is apparent from the above description, according to the present invention, the defect in the structure can be surely detected, and in particular, the accuracy rate of the defect determination can be increased.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an apparatus for practicing the present invention.

FIG. 2 is a schematic view showing an example of a wall surface of a target structure.

FIG. 3 is a graph of experimental results of the present invention.

FIG. 4 is a graph of experimental results of the present invention.

FIG. 5 is a graph of experimental results of the present invention.

FIG. 6 is a graph of experimental results of the present invention.

FIG. 7 is a graph of experimental results of the present invention.

FIG. 8 is a graph of experimental results of the present invention.

FIG. 9 is a graph of experimental results of the present invention.

FIG. 10 is a graph of experimental results of the present invention.

FIG. 11 is a graph of experimental results of the present invention.

FIG. 12 is a graph of experimental results of the present invention.

FIG. 13 is a graph showing experimental results of the present invention.

FIG. 14 is a graph of experimental results of the present invention.

[Explanation of symbols]

1 ... Model building, 2A-2D ... Infrared radiometer (thermal image detector), 10 ... Structure.

────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] January 11, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0018

[Correction method] Change

[Correction contents]

At night, heat transfer in the opposite direction occurs in which the heat energy absorbed by the structure is dissipated to the outside air having a low temperature. Therefore, the temperature of the surface of the structure is low,
High internal temperature causes reversal phenomenon. Under this reversal phenomenon, the temperature difference between the defective portion and the non-defective part also, those of the defective portion occurs is "reversal phenomenon of temperature difference" temperature is lower than the non-defective part.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Susumu Harashima 1-5-1, Marunouchi, Chiyoda-ku, Tokyo Nitto Kagaku Kogyo Co., Ltd.

Claims (3)

[Claims] 1. A method for detecting defects in a structure by detecting radiant energy from the surface of an outdoor structure by means of an infrared radiation thermometer, at least on a day when there is fine weather at 19: 00 to that day. The structure surface temperature was measured by the infrared radiation thermometer within 4:30 of the next day, and the temperature difference with the surroundings was 0.3 ° C or more, and the temperature was low. A method for detecting a defect in a structure, characterized by determining that there is a defect. 2. The structure according to claim 1, wherein the surface temperature of the structure is measured at least once in the daytime and at least once in the time zone, and defects are comprehensively determined on the basis of the surface temperature measurement results of both. How to detect defects in objects. 3. The structure surface temperature is detected also in the daytime of the day, and the temperature difference between the structure surface temperature during the daytime and the nighttime time zone is + 0.3 ° C. or more in the daytime, and at nighttime. The method for detecting a defect in a structure according to claim 1, wherein it is determined that a region having a temperature of −0.3 ° C. or higher has a defect.