Concrete structure deterioration detection system and deterioration detection device

Abstract

To provide a deterioration place detection system for a concrete structure and a deterioration place detection device of the system that can be used frequently without destroying the concrete structure, can evaluate the entire concrete structure without being limited to a predetermined investigation place, and can repeatedly evaluate any number of places at any number of times using a simple device in a non-destructive manner.SOLUTION: A deterioration place detection system according to the present invention includes: a first sensor 2 and a plurality of second sensors 3 arranged around the first sensor 2 at predetermined intervals; close contact means for bringing the first sensor 2 and the second sensors 3 into close contact with the surface of a concrete structure 1; elastic wave generating means for generating elastic waves by hitting a position in the vicinity of the first sensor 2 and the second sensors 3 that are in close contact with the surface of the concrete structure 1; storage means 4 for storing elastic wave data received by the first sensor 2 and the second sensors 3; and deterioration place detection means 5 for detecting deterioration places of the concrete structure 1 by analyzing the stored elastic wave data.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a deterioration detection system for concrete structures, which can repeatedly diagnose and inspect the surface deterioration of a concrete structure, not just at a predetermined detection point, without locally destroying the concrete structure, for example by core sampling or drilling, and to a deterioration detection device for the system. [Background technology]

[0002] Deterioration of concrete structures can be attributed to "surface deterioration," which occurs when fine cracks and porosity develop due to environmental factors over time (such as abrasion, freeze-thaw, chemical erosion, and fatigue), weakening the surface. Concrete with this surface deterioration must be renewed using a cross-section repair method, in which the weakened concrete sections are removed and the removed sections are repaired with new concrete or other materials.

[0003] When renovating, it is reasonable to remove only the weakened concrete and repair the cross section while leaving the sound concrete in place. However, in the case of concrete structures with superficial deterioration, in order to investigate "how far below the surface the concrete has weakened," it has been necessary to rely on destructive sampling methods, such as taking cores by boring and observing them, or drilling holes and judging by touch.

[0004] Furthermore, investigations using sample collection methods such as core sampling and drilling are destructive and therefore cannot be used frequently, resulting in localized assessments. It is unclear whether such localized assessments can be used as representative values ​​for the concrete structure in question, and they can sometimes result in overestimations, resulting in incomplete removal of weakened concrete or removal of too much sound concrete. Furthermore, because the investigation area is lost due to destruction, it is not possible to confirm changes over time by conducting repeated investigations at the same location, making this method irrational.

[0005] For the above reasons, the most rational investigation method for cross-sectional repair of concrete structures with surface deterioration is to minimize the need for (destructive) sampling to directly assess the actual condition, and to develop non-destructive investigation techniques that can assess "how far from the surface the concrete has weakened" in any number of locations and any number of times before sampling so that the results obtained from sampling can be used more effectively, and to compare and evaluate the results with the samples taken. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2019-56683 Summary of the Invention [Problem to be solved by the invention]

[0007] Thus, the present invention has been devised to address the above-mentioned conventional problems, and aims to provide a non-destructive deterioration detection system and deterioration detection device for concrete structures that can be used in a variety of ways without destroying the concrete structure, that allows evaluation of the entire concrete structure rather than being limited to specific inspection locations, and because it does not involve destruction, the inspection location is not lost and changes over time can be confirmed through inspection at the same location as many times as necessary, and that can be repeatedly evaluated at any number of locations using simple equipment. [Means for solving the problem]

[0008] The present invention provides A first sensor for detecting a deteriorated portion of a concrete structure and The sensors are arranged at equal intervals on a circular periphery separated from the first sensor. Multiple a second sensor; the plurality of second sensors are arranged such that no other second sensor is arranged on a straight line passing through an arrangement position of the second sensor and an arrangement position of the first sensor, an elastic wave generating means for generating elastic waves by striking a position near the first sensor and the second sensor that are in close contact with the surface of the concrete structure; a storage means for storing data of elastic waves received by the first sensor and the second sensor; and a deterioration portion detection means for analyzing the stored elastic wave data to detect deterioration portions of the concrete structure. Equipped with The range for detecting the deteriorated portion of the concrete structure is a range from the surface of the concrete structure in a depth direction of the concrete structure, The deterioration location detection means obtains complex coherence for each elastic wave from the elastic waves obtained by the plurality of second sensors and the first sensor arranged on a circular periphery, calculates an average SPAC coefficient, calculates a frequency and a surface wave phase velocity for that frequency from the calculated SPAC coefficient, detects a depth from the surface of the concrete structure using the calculated frequency, and can detect deterioration locations in the concrete structure at the detected depth by detecting the surface wave phase velocity for that frequency. It is characterized by the fact that or A first sensor for detecting a deteriorated portion of a concrete structure and The sensors are arranged at equal intervals on a circular periphery separated from the first sensor. Multiple a second sensor; the plurality of second sensors are arranged such that no other second sensor is arranged on a straight line passing through an arrangement position of the second sensor and an arrangement position of the first sensor, an elastic wave generating means for generating elastic waves by striking a position near the first sensor and the second sensor that are attached to the surface of the concrete structure; a storage means for storing data of elastic waves received by the first sensor and the second sensor; and a deterioration portion detection means for analyzing the stored elastic wave data to detect deterioration portions of the concrete structure. Equipped with The range for detecting the deteriorated portion of the concrete structure is a range from the surface of the concrete structure in a depth direction of the concrete structure, the deterioration location detection means obtains complex coherence for each elastic wave obtained by the elastic waves obtained by the plurality of second sensors and the first sensor arranged on a circular periphery, calculates an average SPAC coefficient, calculates a frequency and a surface wave phase velocity for that frequency from the calculated SPAC coefficient, detects a depth from the surface of the concrete structure using the calculated frequency, and can detect deterioration locations in the concrete structure at the detected depth by detecting the surface wave phase velocity for that frequency; and an image generating means for drawing the detected deteriorated portion of the concrete structure as an image. It is characterized by the fact that or The calculation of the frequency and surface wave phase velocity utilizes the characteristic that high frequencies (short wavelengths) propagate in shallow areas near the surface of a concrete structure, and low frequencies (long wavelengths) propagate from the surface of a concrete structure to deep areas in the depth direction, and that if the concrete structure is sound, the surface wave phase velocity will be uniformly fast even if the frequency changes, and if the concrete structure is deteriorated, the surface wave phase velocity will be slower. It is characterized by the fact that or The range for detecting deteriorated portions of the concrete structure is a cylindrical range having a length in the depth direction of the concrete structure from a surface range surrounded by a circular periphery line spaced from a first sensor arranged on the surface of the concrete structure. It is characterized by the fact that or Regarding the cylindrical range having a length in the depth direction of the concrete structure, the range of the length in the depth direction is The distance between the first sensor and the second sensor is defined as a radius, and the depth range has a length 2 to 10 times the radius. It is characterized by the fact that or the image generating means is capable of drawing a three-dimensional image in which colors are arranged in layers and a core is cut out in a substantially cylindrical shape using the calculated frequency and data on the surface wave phase velocity for the frequency; It is characterized by the following. [Effects of the Invention]

[0009] According to the present invention, the method can be used in a variety of ways without destroying the concrete structure, and allows evaluation of the entire concrete structure rather than being limited to a specific inspection location. Furthermore, since no destruction is involved, the inspection location is not lost and changes over time can be confirmed through inspection at the same location as many times as necessary, and evaluation can be performed repeatedly at any number of locations using a simple device. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is an explanatory diagram (1) illustrating the configuration of a deterioration part detection system according to the present invention. [Figure 2] FIG. 2 is an explanatory diagram (2) illustrating the configuration of the deterioration part detection system of the present invention. [Figure 3] FIG. 10 is an explanatory diagram illustrating the relationship between frequency and distance in the depth direction of a concrete structure. [Figure 4] FIG. 2 is a schematic diagram illustrating the configuration of a deterioration portion detection unit. [Figure 5] FIG. 2 is a schematic diagram illustrating the configuration of a control unit of a deterioration portion detection means. [Figure 6] FIG. 1 is an explanatory diagram illustrating the configurations of concrete specimens A to D with different depths of surface deterioration. [Figure 7] FIG. 1 is an explanatory diagram illustrating the results obtained using concrete specimens A to D with different depths of surface deterioration. [Figure 8] 1 is a schematic diagram (1) illustrating the configuration of a deterioration portion detection device for a concrete structure using the deterioration portion detection system of the present invention. [Figure 9] 1 is a schematic diagram (2) illustrating the configuration of a deterioration portion detection device for a concrete structure using the deterioration portion detection system of the present invention. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0011] The present invention will be described below based on examples. The configuration of the deterioration detection system of the present invention is shown in Figure 1. Figure 1 is a perspective view of the various sensors arranged from above, and the dashed lines in the figure are drawn to help understand the arrangement of the various sensors, which will be explained below.

[0012] 1, a first sensor 2 is placed on the surface of a concrete structure 1, and a plurality of second sensors 3 are placed at predetermined intervals around the first sensor 2, with the first sensor 2 at the center. The plurality of second sensors 3 are placed at equal intervals on a periphery line spaced apart from the first sensor 2.

[0013] Here, one of the features of this system is that it is important to arrange the second sensors 3 at equal intervals on a circumferential line spaced apart from the first sensor 2. In Fig. 1, three second sensors 3 are arranged on a circumferential line with a radius of approximately 25 mm centered on the first sensor 2, at positions that divide the circumferential line into three equal parts.

[0014] Another important feature is that the second sensors 3 are arranged such that no other second sensors 3 are arranged on a straight line passing from the second sensor 3 to the first sensor 2 .

[0015] That is, the second sensors 3 arranged on a circumferential line centered on the first sensor 2 must divide the circumferential line equally and be arranged at equal intervals on the circumferential line, and the first sensor 2 and the second sensors 3 must not be arranged on a straight line. Therefore, as long as the arrangement conditions for the second sensors 3 are met, the number and arrangement of the second sensors 3 are not limited to the configuration shown in Fig. 1.

[0016] Incidentally, a storage means 4 is connected to the first sensor 2 and the plurality of second sensors 3 (see FIG. 2) for recording and storing data of elastic waves received by the first sensor 2 and the plurality of second sensors 3. As the storage means 4, for example, a waveform recording device such as a data logger is used.

[0017] The elastic wave data stored in the storage means 4 is then analyzed by a deteriorated portion detection means 5 to evaluate the deterioration state of the concrete structure 1 within the circumferential line on which the plurality of second sensors 3 are arranged. The deteriorated portion detection means 5 is, for example, a waveform analysis device such as a computer.

[0018] Here, the range for evaluating the deterioration state is the range from the surface of the concrete structure 1 in the depth direction of the concrete structure 1. The distance between the first sensor 2 and the second sensor 3 is defined as the radius, and the depth of the concrete structure 1 is 2 to 10 times this radius, i.e., a roughly cylindrical range, is the range for evaluating the deterioration state.

[0019] For example, when the distance (radius) between the first sensor 2 and the second sensor 3 is 25 mm as shown in Fig. 1, the evaluation range can be evaluated from the surface of the concrete structure 1 to a depth of 50 to 250 mm in the depth direction. Note that, if the influence of reflected waves from the opposite surface (back surface) is expected as the distance gets closer to the opposite surface (back surface) of the concrete structure 1, it is preferable to determine the evaluation range in the depth direction taking this influence into consideration.

[0020] Next, the analysis method will be explained with reference to FIG. Elastic waves are generated by striking the surface of the concrete structure 1 evenly for a certain period of time at positions near the plurality of second sensors 3 arranged on the surface of the concrete structure 1 with an elastic wave generating means. The elastic wave generating means is, for example, an elastic wave oscillator 6 such as a hammer.

[0021] The generated elastic waves are received by the first sensor 2 and the plurality of second sensors 3, and the received elastic waves are recorded and stored as data by the storage means 4. From the stored elastic wave data, the deterioration location detection means 5 determines the complex coherence between the plurality of second sensors 3 arranged on a circumferential line and the first sensor 2 for each elastic wave, and calculates the SPAC coefficient by averaging these.

[0022] Since the SPAC coefficient is a function of the frequency (kHz) and surface wave phase velocity (m / s) contained in the stored elastic waves, the surface wave phase velocity for the frequency can be calculated by optimization processing. The calculated frequency evaluates the wavelength, that is, the depth from the surface of the concrete structure 1, and the surface wave phase velocity is an index for evaluating the soundness of the concrete structure 1.

[0023] Here, Figure 3(a) is a diagram showing the relationship between frequency and depth of concrete structure 1, and Figure 3(b) is a diagram showing the relationship between frequency and depth of surface wave phase velocity when concrete structure 1 is sound and when it is weak.

[0024] As can be seen from Figure 3(a), higher frequencies (shorter wavelengths) have the characteristic of propagating shallowly near the surface of the concrete structure 1, while lower frequencies (longer wavelengths) have the characteristic of propagating deep from the surface of the concrete structure 1. Also, from Figure 3(b), it can be seen that when the concrete structure 1 is sound, the surface wave phase velocity remains uniformly fast even if the frequency is changed, but when it is vulnerable due to corrosion or other deterioration, the surface wave phase velocity slows down.

[0025] As can be seen from Figures 3(a) and (b), the surface wave phase velocity for higher frequencies (shorter wavelengths) can be used to evaluate the soundness of the concrete structure 1 from the surface to shallow depths, while the surface wave phase velocity for lower frequencies (longer wavelengths) can be used to evaluate the soundness of the concrete structure 1 from the surface to deeper depths.

[0026] The deterioration part detection means 5 is configured to include a receiving unit 7, a transmitting unit 8, a control unit 9, a storage unit 10, an input unit 11, and a display unit 12 (see FIG. 4). The elastic wave data recorded and stored by the storage means 4 is received by the receiving unit 7 of the deterioration part detection means 5, and the received elastic wave data is processed in the control unit 9.

[0027] The control unit 9 is configured to include a data reading unit 13, a data processing unit 14, and an image generating unit 15 (see FIG. 5). Therefore, for example, when the deterioration part detecting unit 5 receives elastic wave data from the storage unit 4, the data reading unit 13 of the control unit 9 reads the data, and the read elastic wave data is processed by the data processing unit 14.

[0028] As described above, the data processing unit 14 calculates the complex coherence between the multiple second sensors 3 and the first sensor 2 for each elastic wave, and averages the complex coherence to calculate the SPAC coefficient. The calculated SPAC coefficient is then optimized to calculate the surface wave phase velocity with respect to frequency.

[0029] Thereafter, the information on the surface wave phase velocity for the frequency calculated by the data processing unit 14 is calculated by the image generating means 15, and the deteriorated areas of the concrete structure 1 where the first sensor 2 and the multiple second sensors 3 are arranged are depicted as an image such as a two-dimensional image or a three-dimensional image to generate an image (see Figures 7(a) and (b)).

[0030] For example, a cored image can be formed by layering the generated image of the concrete structure 1 up to (a circle with a radius where the first sensor 2 and the plurality of second sensors 3 are arranged) x {depth corresponding to the frequency (wavelength)} based on the surface wave phase velocity (m / s) for each frequency (each wavelength) contained in the elastic wave and drawing it in an approximately cylindrical shape (see Figure 7(b)). The cored image makes it possible to evaluate the soundness of the location where the sensor is arranged at a glance. Note that this image can be selected as a planar image, a three-dimensional image, or other image using a predetermined application software and a PC that calculates and controls it. By drawing a planar image, a three-dimensional image, or other image using the image generation unit 26 of the image generation means 15, the deteriorated areas can be clearly recognized.

[0031] Furthermore, the two-dimensional image or the three-dimensional image can be color-coded by the coloring unit 27 of the image generating means 15. If the two-dimensional image or the three-dimensional image can be color-coded as shown in Fig. 7(b), it becomes possible to clearly recognize at a glance the degree of deterioration at what depth. The generated image is stored in the storage unit 10 of the deteriorated portion detection means 5 and is also displayed on the display unit 12.

[0032] As a result, while conventionally, investigations of deterioration, etc. of concrete structures 1 have been carried out by locally destructive means such as core sampling or drilling, the deterioration detection system of the present invention does not involve destruction of the concrete structure 1, and therefore can repeatedly evaluate any number of locations. Furthermore, by actually sampling only the locations where weakness has been confirmed by this system and comparing the results of the sampling, it is possible to rationally estimate the concrete that has deteriorated or become weakened, and this can be used to help with cross-sectional repair methods (renewal) when repairing it.

[0033] Next, an example in which the first sensor 2 and the multiple second sensors 3 are arranged in the same manner as in FIG. 1 and are installed in close contact with the surfaces of concrete specimens A to D, and the results thereof will be described with reference to FIGS. 6 and 7.

[0034] Figure 6 shows concrete specimens A to D, which have different depths of surface deterioration, simulating weakening by making the concrete porous. Concrete specimen A is sound throughout, concrete specimen B is weak in the cover (surface), concrete specimen C is weak in the upper half, and concrete specimen D is weak throughout.

[0035] The dimensions of the test specimen were 900 mm in length, 780 mm in width, and 300 mm in thickness. Furthermore, at approximately the center of the surface (top surface) of concrete test specimens A to D, as shown in Figure 1, three second sensors 3 were placed on a circumferential line with a radius of approximately 25 mm centered on the first sensor 2, at positions that divide the circumferential line into three equal parts, and were installed in close contact with the concrete test specimens.

[0036] After the first sensor 2 and the plurality of second sensors 3 were installed in a state of close contact, the elastic wave generating means 6 was used to strike the vicinity of the first sensor and the second sensors evenly for about 10 seconds to generate elastic waves.

[0037] The generated elastic waves were received by the first sensor 2 and the plurality of second sensors 3, and the received elastic waves were recorded and stored as data in the storage means 4. The stored elastic wave data was analyzed by the deteriorated portion detection means 5, and the deterioration state of the concrete specimens A to D was evaluated.

[0038] As already explained, the range for evaluating the deterioration state is the evaluation range from the surface (top surface) in the depth direction. Since the distance (radius) between the first sensor 2 and the second sensor 3 is 25 mm, the evaluation can be performed up to a depth of 50 to 250 mm from the surface (top surface) in the depth direction, which is 2 to 10 times the radius. In other words, the range for evaluating the deterioration state is an approximately cylindrical range.

[0039] The maximum depth to be evaluated is 250 mm, but as the thickness approaches that of concrete specimens A to D in this example, there is a possibility that the direct waves (P waves) will not be properly analyzed due to the reflected waves from the opposite side (back side). Therefore, in this example, the maximum depth is set to 200 mm, and the depth of 200 mm from the surface (top surface) is used to evaluate the state of deterioration.

[0040] FIG. 7 shows the results obtained in this example. In Figure 7, if the surface wave phase velocity is arbitrarily 2,100 (m / s) or more, the concrete specimen is considered to be sound and is colored blue; if the surface wave phase velocity is less than 1,900 (m / s), the concrete specimen is considered to be abnormal and is colored red; and if the surface wave phase velocity is between 1,900 (m / s) and 2,100 (m / s), the concrete specimen is considered to require attention (transition zone) and is colored yellow. Note that the attached Figure 7 can only be displayed in monochrome, not in color, so dark shades are judged to be blue, medium shades to be red, and light shades to be yellow.

[0041] 7(a) is a planar image depicting the evaluation results for each concrete specimen. The vertical axis represents the depth from the surface (top surface), and the horizontal axis represents each of concrete specimens A to D. The bar graph for each concrete specimen changes frequency (wavelength) from low to high from left to right, and the numerical values ​​in the bar graph represent the surface wave phase velocity (m / s) for that frequency (wavelength).

[0042] Next, Figure 7(b) is a three-dimensional image of the evaluation results for each concrete specimen. The surface wave phase velocity (m / s) for each frequency (each wavelength) is color-coded in layers, and the core image is drawn in the shape of an approximately cylindrical column with a diameter of 50 mm and a depth of 200 mm.

[0043] From Figure 7, it is possible to evaluate the depth of surface deterioration of concrete specimens A to D, and in particular, the core image in Figure 7(b) was found to be effective in enabling a quick evaluation of the soundness or weakening of concrete specimens A to D, such as deterioration.

[0044] Next, a deterioration part detection device 16 for a concrete structure 1 that utilizes the deterioration part detection system of the present invention will be described with reference to Figures 8 and 9. Note that the deterioration part detection device 16 shown in Figures 8 and 9 is just an example, and the deterioration part detection device 16 is not limited to the configuration or shape shown in Figures 8 and 9.

[0045] First, the deteriorated portion detecting device 16 shown in FIG. 8 will be described. The deterioration detection device 16 is configured to include a sensor section 17 having a first sensor 2 and a plurality of second sensors 3, a detection body 18 to which the sensor section 17 is attached, and a gripping section 24 provided on the side of the detection body 18 opposite the sensor attachment side.

[0046] The detection body 18 has a pressure plate 19 that constitutes the detection body 18, a first mounting rod 20 with the first sensor 2 attached to its tip, and a second mounting rod 21 with the second sensor 3 attached to its tip.

[0047] Here, the pressing plate 19 serves as a contact means for bringing the first sensor 2 and the second sensor 3 into close contact with the surface of the concrete structure 1 and pressing them against the surface side of the concrete structure 1.

[0048] The first mounting rod 20 penetrates the central shaft portion of the pressing plate 19 and protrudes, and the first sensor 2 is attached to the protruding tip end side via a mounting member 22.

[0049] A plurality of second mounting rods 21 are provided, extending radially from the first mounting rod 20, and the second sensor 3 is attached to the tip end of the second mounting rod 21 via an attachment member 22. In FIG. 8, three second mounting rods 21 are attached radially from the first mounting rod 20.

[0050] Here, the mounting member 22 is provided between the sensor and the first mounting rod 20 or the second mounting rod 32, and in addition to attaching both members, it also serves as a buffer material. The deterioration detection device 16 of the present invention is used by being pressed against the surface of the concrete structure 1 while being in close contact with the surface, and therefore prevents damage to the various sensors of the sensor unit 17 when excessive pressure is applied.

[0051] A retaining rod 23 is provided between the first mounting rod 20 and the second mounting rod 21, extending obliquely from the mounting member 22 of the first mounting rod 20 toward approximately the middle of the second mounting rod 21. The retaining rod 23 maintains the state in which the second mounting rod 21 extends radially from the first mounting rod 20, and also serves to reinforce the second mounting rod 21 so that it does not expand radially more than necessary when pressed against the surface of the concrete structure 1.

[0052] 8(a) and 8(b), the first sensor 2 and the second sensors 3 are configured to be at the same height. As a result, when the first sensor 2 and the second sensors 3 are brought into contact with the surface of the concrete structure 1 and brought into close contact with the surface, the first sensor 2 and the second sensors 3 are brought into close contact with each other evenly, and the deterioration state of the concrete structure 1 can be accurately detected.

[0053] 8(b), the second mounting rod 21 is configured so that the radiation angle can be changed. That is, when the radiation angle of the second mounting rod 21 is increased, the distance between the first sensor 2 and the plurality of second sensors 3 is increased.

[0054] As already explained, if the distance between the first sensor 2 and the second sensor 3 is taken as a radius, it is possible to evaluate the state of deterioration up to a depth of the concrete structure 1 that is 2 to 10 times that radius. In other words, by changing the radiation angle of the second mounting rod 21 depending on the concrete structure 1 to be evaluated, it is possible to properly evaluate the depth of the concrete structure 1.

[0055] Furthermore, when the second mounting rod 21 expands radially and the radiation angle changes, the holding rod 23 is pulled by the second mounting rod 21, and in response to this pulling, the first mounting rod 20 penetrates the pressure plate 19 and protrudes toward the gripping portion 24. As a result, as can be seen from the side view of Figure 8 (b), the first sensor 2 and the second sensor 3 are at the same height, and the first sensor 2 and the second sensor 3 can be evenly and tightly attached to the surface of the concrete structure 1 as described above.

[0056] Next, the deteriorated portion detecting device 16 shown in FIG. 9 will be described. The deterioration detection device 16 is configured to include a sensor section 17 having a first sensor 2 and a plurality of second sensors 3, a detection body 18 to which the sensor section 17 is attached, and a gripping section 24 provided on the side of the detection body 18 opposite to the sensor attachment side, as in Figure 8.

[0057] The detection body 18 of the deterioration detection device 16 shown in Figure 9 has a pressure plate 19 that constitutes the detection body 18, an attachment member 22 to which the first sensor 2 is attached, and an attachment rod 25 that has the second sensor 3 attached to its tip and is arranged parallel to the pressure plate 19.

[0058] The pressing plate 19 serves as a contact means for bringing the first sensor 2 and the second sensor 3 into close contact with the surface of the concrete structure 1 and pressing them against the surface of the concrete structure 1. Although the pressing plate 19 is shown in a substantially circular plate shape in Figures 8 and 9, it is not limited to a substantially circular plate shape and may have any shape that allows the sensor unit 17 to be sufficiently pressed against the surface of the concrete structure 1.

[0059] The mounting rod 25 has a base end attached to the mounting member 22 of the first sensor 2, and is provided to extend radially from the mounting member 22 of the first sensor 2. The second sensor 3 is attached to the tip side of the mounting rod 25 via the mounting member 22.

[0060] Here, the mounting member 22 is provided between the sensor and the pressure plate 19, and in addition to attaching them to each other, it also serves as a buffer material. The deterioration detection device 16 of the present invention is used by being pressed against the surface of the concrete structure 1 while being in close contact with the surface, and therefore prevents damage to the various sensors of the sensor unit 17 when excessive pressure is applied.

[0061] 9(b), the extension length of the mounting rod 25 is adjustable. By extending the tip of the mounting rod 25, the distance between the first sensor 2 and the second sensor 3 can be increased, and as a result, the distance in the depth direction of the concrete structure 1 can be adjusted.

[0062] As shown in Figures 8 and 9, the deterioration location detection device 16 is not limited to one configured so that the distance between the first sensor 2 and the multiple second sensors 3 can be changed, but may also be a device in which the first sensor 2 and the multiple second sensors 3 are fixed in advance at predetermined positions on the pressure plate 19.

[0063] The elastic wave data obtained using the deterioration part detection device 16 is recorded and stored in the storage means 4. The elastic wave data stored in the storage means 4 is then analyzed by the deterioration part detection means 5 to evaluate the deterioration state of the concrete structure 1 within the circumferential line on which the plurality of second sensors 3 are arranged. [Explanation of symbols]

[0064] 1. Concrete structures 2 First sensor 3 Second sensor 4 Storage means 5. Deterioration detection method 6 Elastic wave generating means 7. Receiving section 8. Transmitter 9 Control Unit 10 Storage area 11 Input section 12 Display section 13 Data reading section 14 Data processing section 15 Image generation means 16 Deterioration detection device 17 Sensor section 18 Detector body 19 Retaining plate 20 1st mounting rod 21 2nd mounting rod 22 Mounting material 23 Retaining rod 24 Gripping part 25 Mounting rod 26 Image generation unit 27 Color scheme

Claims

1. a first sensor for detecting a deteriorated portion of a concrete structure, and a plurality of second sensors arranged at equal intervals on a circular periphery separated from the first sensor; the plurality of second sensors are arranged such that no other second sensor is arranged on a straight line passing through an arrangement position of the second sensor and an arrangement position of the first sensor, an elastic wave generating means for generating elastic waves by striking a position near the first sensor and the second sensor that are in close contact with the surface of the concrete structure; a storage means for storing data of elastic waves received by the first sensor and the second sensor, and a deterioration portion detection means for analyzing the stored elastic wave data to detect a deterioration portion of the concrete structure, The range for detecting the deteriorated portion of the concrete structure is a range from the surface of the concrete structure in a depth direction of the concrete structure, The deterioration location detection means obtains complex coherence for each elastic wave from the elastic waves obtained by the plurality of second sensors and the first sensor arranged on a circular periphery, calculates a SPAC coefficient by averaging the complex coherence, calculates a frequency and a surface wave phase velocity for the frequency from the calculated SPAC coefficient, detects a depth from the surface of the concrete structure using the calculated frequency, and can detect deterioration locations in the concrete structure at the detected depth by detecting the surface wave phase velocity for the frequency. A deterioration detection system for a concrete structure.

2. a first sensor for detecting a deteriorated portion of a concrete structure, and a plurality of second sensors arranged at equal intervals on a circular periphery separated from the first sensor; the plurality of second sensors are arranged such that no other second sensor is arranged on a straight line passing through an arrangement position of the second sensor and an arrangement position of the first sensor, an elastic wave generating means for generating elastic waves by striking positions near the first sensor and the second sensor that are in close contact with the surface of the concrete structure; a storage means for storing data of elastic waves received by the first sensor and the second sensor, and a deterioration portion detection means for analyzing the stored elastic wave data to detect a deterioration portion of the concrete structure, The range for detecting the deteriorated portion of the concrete structure is a range from the surface of the concrete structure in a depth direction of the concrete structure, the deterioration location detection means obtains complex coherence for each elastic wave obtained by the elastic waves obtained by the plurality of second sensors and the first sensor arranged on a circular periphery, calculates a SPAC coefficient by averaging the complex coherence, calculates a frequency and a surface wave phase velocity for the frequency from the calculated SPAC coefficient, detects a depth from the surface of the concrete structure using the calculated frequency, and can detect deterioration locations in the concrete structure at the detected depth by detecting the surface wave phase velocity for the frequency; and an image generating means for drawing the detected deteriorated portion of the concrete structure as an image. A deterioration detection system for a concrete structure.

3. The calculation of the frequency and surface wave phase velocity utilizes the characteristic that high frequencies (short wavelengths) propagate in shallow areas near the surface of a concrete structure, and low frequencies (long wavelengths) propagate from the surface of a concrete structure to deep areas in the depth direction, and that when the concrete structure is sound, the surface wave phase velocity remains uniformly fast even if the frequency changes, and when the concrete structure is deteriorated, the surface wave phase velocity becomes slower.

2. The system for detecting deteriorated portions of a concrete structure according to claim 1.

4. The range for detecting deteriorated areas of the concrete structure is a cylindrical range having a length in the depth direction of the concrete structure from the surface range surrounded by a circular outer periphery spaced from the first sensor placed on the surface of the concrete structure, 2. The system for detecting deteriorated parts of a concrete structure according to claim 1.

5. With respect to a cylindrical range having a length in the depth direction of the concrete structure, the range of length in the depth direction is a depth range having a length 2 to 10 times the radius of the distance between the first sensor and the second sensor, 4. The system for detecting deteriorated portions of a concrete structure according to claim 3.

6. the image generating means is capable of drawing a three-dimensional image in which colors are arranged in layers and a core is cut out in a substantially cylindrical shape using the calculated frequency and data on the surface wave phase velocity for the frequency; 3. The system for detecting deteriorated portions of a concrete structure according to claim 2.

Images