Arch bridge void infrared detection device and detection method

Abstract

The invention relates to an infrared detection device and method for arch bridge void, and the method comprises the following steps: S1, adjusting the temperature of the surface of an arch rib to T1 when the concrete strength reaches 70%, and obtaining a three-dimensional profile diagram and an infrared image of the arch rib; s2, after the arch rib and the reinforcing rod are welded, a detection area is determined; s3, adjusting the temperature of the detection area to T1, and obtaining a three-dimensional profile diagram and an infrared image of the detection area; s4, finding out a region corresponding to the detection region from the three-dimensional contour map obtained in the step S1 as a first reference map, comparing the three-dimensional contour map of the detection region with the first reference map, calculating the deformation amount of the detection region, and detecting whether the inner side of the connecting surface of the arch rib and the reinforcing rod is void or not again when the deformation amount is greater than a set value; and judging whether the detection area is void or not according to the infrared image of the detection area. According to the invention, more perfect and effective void detection can be carried out on the welding part of the reinforcing rod and the arch rib.

Description

Technical Field

[0001] The invention belongs to the technical field of void detection, and in particular to an infrared detection device and method for void detection in an arch bridge. Background Art

[0002] Concrete-filled steel tube arch ribs have excellent compressive strength and toughness, capable of withstanding large horizontal and vertical loads, making them a commonly used component in arch bridges. Voids, defined as gaps or interfacial separations between the concrete and the steel tube, can lead to adverse consequences such as reduced bearing capacity of the arch rib structure, increased risk of steel tube rupture, and increased probability of structural deformation and instability. Therefore, void detection of concrete-filled steel tube arch ribs is essential.

[0003] Void detection methods include infrared thermal imaging detection, ultrasonic detection, and tapping method. Among them, the tapping method is the most convenient, but it relies on the experience of the detection personnel and is suitable for preliminary screening; ultrasonic detection can detect the depth of voids, but it requires coupling agents and has high requirements for operation. For arch bridges that have been completed, high-altitude operations are required during detection, which is very difficult to operate. Infrared thermal imaging detection has become a relatively common method for void detection because of its low operating difficulty and low requirements for equipment and personnel. The principle of infrared detection is: the thermal conductivity of the void area is different from that of the non-void part, and a significant temperature difference is formed under external excitation (heating or cooling). An infrared thermal imager is used to obtain a thermal image of the steel pipe surface, and relevant software is used to analyze and identify whether voids occur. For example, the invention patent CN201810258818.1 discloses a non-destructive detection system and method for voids in steel tube concrete, including an eddy current heating device for heating steel tube concrete. When alternating current is passed through the eddy current heating device, eddy currents can be generated on the steel tube surface of the steel tube concrete, causing the steel tube concrete to be heated; it also includes an infrared thermal imager for collecting infrared video and a computer equipped with void recognition software. The void recognition software can extract infrared images from the infrared video and calculate a temperature curve that changes with time based on the infrared image, thereby identifying whether there are voids in the steel tube concrete based on the temperature curve. For example, the invention patent with application number CN202410330152.1 discloses a CFST arch bridge void thickness detection method and system based on cooling excitation intensity. The temperature excitation device is used to perform cooling excitation on the area to be detected of the CFST arch bridge specimen to be tested, and the surface temperature field image data of the area to be detected before and after the cooling excitation is collected; the surface temperature field image data before and after the cooling excitation is processed to determine whether there is a void area; when there is a void area, the area and void thickness of the void area are determined according to the surface temperature field image data before and after the cooling excitation.

[0004] Currently, void detection for concrete-filled steel tube arch ribs is primarily performed during the preparation and operation phases. Specifically, the first void detection is conducted within 7-14 days after concrete pouring (when strength reaches 70% or higher) to ensure a close fit between the concrete and the steel tube, eliminating any initial voids. A second void detection is conducted after arch rib construction is complete. After the arch bridge is operational, routine inspections are conducted every one to two years to detect early voids and prevent further damage. While the first void detection can be conducted on the ground, the second void detection and inspections are typically conducted from high altitude using drones.

[0005] To enhance the strength of arch bridges, reinforcement rods are typically welded between the ribs during arch rib construction. This welding process can easily cause thermal deformation and stress concentration in the steel pipes, increasing the risk of voids. After the reinforcement rods are welded to the arch ribs, the weld surface between the ribs and the reinforcement rods is not exposed. Infrared thermal imaging cameras cannot fully scan the entire surface of the arch ribs, resulting in incomplete inspections. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide an infrared detection device and method for detecting hollow spaces in arch bridges, which can perform more complete and effective hollow space detection on the welding points between reinforcing rods and arch ribs.

[0007] To solve the above problems, the present invention adopts the following technical solution: an infrared detection method for arch bridge hollowness, comprising the following steps:

[0008] S1. After concrete is poured into the steel pipe of the arch rib, when the concrete strength reaches 70%, the temperature of the arch rib surface is adjusted to T1. Then, the arch rib is scanned using a 3D scanning device and an infrared thermal imager to obtain a 3D contour map and infrared image of the arch rib;

[0009] S2. After the arch ribs and the reinforcing rods are welded, determine the inspection area. The inspection area is located around the connection surface between the arch ribs and the reinforcing rods.

[0010] S3. Adjust the temperature of the detection area to T1, scan the detection area using a three-dimensional scanning device and an infrared thermal imager, and obtain a three-dimensional contour map and infrared image of the detection area;

[0011] S4. Find the area corresponding to the detection area in the three-dimensional contour map obtained in step S1 as the first reference map, compare the three-dimensional contour map of the detection area with the first reference map, calculate the deformation of the detection area, and when the deformation is greater than the set value, re-check whether the inner side of the connection surface between the arch rib and the reinforcing rod is hollow; determine whether the detection area is hollow based on the infrared image of the detection area.

[0012] Furthermore, in step S4, when the radial deformation of the detection area is greater than 0.1%, it is again detected whether the inner side of the connection surface between the arch rib and the reinforcing rod is empty.

[0013] Furthermore, in step S4, when the deformation is greater than the set value, ultrasonic waves are used to detect again whether the inner side of the connection surface between the arch rib and the reinforcing rod is hollow.

[0014] Furthermore, in step S4, an area corresponding to the detection area is found in the infrared image obtained in step S1 as a second reference image, and the infrared image of the detection area is compared with the second reference image to find the void area.

[0015] Furthermore, in steps S1 and S3, liquid nitrogen is used to reduce the temperature of the rib surface to -30°C.

[0016] The infrared detection device for arch bridge voids used to implement the above-mentioned infrared detection method for arch bridge voids includes a mobile carrier and a processor, the mobile carrier is provided with an infrared thermal imager and a temperature control mechanism, the infrared thermal imager is communicatively connected to the processor, the mobile carrier is provided with a three-dimensional scanning device, and the three-dimensional scanning device is communicatively connected to the processor.

[0017] Furthermore, the mobile carrier is a heavy-loaded drone, and a first bracket and a second bracket are respectively provided on both sides of the heavy-loaded drone. The temperature control mechanism is installed on the first bracket, and a mounting bracket is provided at the end of the second bracket. The two ends of the mounting bracket are installed on the mounting bracket through a mounting shaft, and the mounting shaft is connected to a drive motor; the three-dimensional scanning equipment and the infrared thermal imager are both installed on the mounting bracket.

[0018] Furthermore, the mobile carrier is connected to an arc-shaped track, and an arc-shaped first cooling plate, an arc-shaped second cooling plate and an arc-shaped third cooling plate are provided on the track, the first cooling plate and the second cooling plate are both slidably matched with the track, the third cooling plate is fixedly connected to the inner side of the track, and the first cooling plate, the second cooling plate and the third cooling plate are all hollow plates, and an arc-shaped flexible conveying pipe is provided between the first cooling plate and the second cooling plate, and the two ends of the flexible conveying pipe are respectively connected to the inner cavity of the first cooling plate and the second cooling plate through a one-way valve, and the first cooling plate and the second cooling plate are provided with a semicircular notch at the end away from the flexible conveying pipe, the first cooling plate, the second cooling plate and the third cooling plate form a circular cooling cavity, and the inner side surfaces of the first cooling plate, the second cooling plate and the third cooling plate are provided with a spray hole; the temperature control mechanism includes a liquid nitrogen storage tank, and the liquid nitrogen storage tank is connected to a conveying pump, and the conveying pump is connected to the flexible conveying pipe and the inner cavity of the third cooling plate through a flexible conveying pipe.

[0019] Furthermore, the first bracket and the second bracket are both arranged horizontally, the first bracket includes a fixed bracket and a movable bracket, the fixed bracket is fixedly connected to the heavy-load drone, the movable bracket and the fixed bracket slide together in the horizontal direction, and the movable bracket is connected to a telescopic mechanism; the temperature control mechanism is installed on the movable bracket.

[0020] The beneficial effects of the present invention are as follows: after welding construction, by performing infrared detection on the detection area around the connection surface between the arch rib and the reinforcing rod, it can be measured whether there is void in the detection area; by detecting the deformation of the arch rib detection area after welding, it is further judged whether there is void on the inner side of the connection surface between the arch rib and the reinforcing rod. When the deformation is small, the probability of void on the inner side of the connection surface between the arch rib and the reinforcing rod is small, so there is no need to perform re-detection. When the deformation is large, the probability of void is large, so re-detection is performed.

[0021] Compared with infrared detection alone, the present invention adds an inspection of deformation in the detection area, which can perform preliminary inspections on whether the inner side of the connection surface between the arch rib and the reinforcing rod is hollow. This improves the comprehensiveness of the inspection, eliminates blind spots, and ensures the accuracy of the inspection. Compared with direct ultrasonic inspection, infrared inspection and three-dimensional profile inspection do not require the application of coupling agent on the surface of the arch rib, and thus require less equipment and personnel, are more convenient to operate, and have higher inspection efficiency. The present invention first uses a combination of infrared inspection and three-dimensional profile inspection for inspection. When the inner side of the connection surface between the arch rib and the reinforcing rod has a high probability of being hollow, ultrasonic inspection and other in-depth inspections are then performed, which not only ensures the inspection efficiency but also improves the inspection accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a flow chart of the infrared detection method for arch bridge hollowing of the present invention;

[0023] Figure 2 This is a schematic diagram of the connection between the arch rib and the reinforcement rod during construction;

[0024] Figure 3 is a schematic diagram of the detection area;

[0025] Figure 4 This is a top view schematic diagram of the heavy-load UAV during testing of the present invention;

[0026] Figure 5 yes Figure 4 Schematic cross-sectional view of AA in the figure;

[0027] Figure 6 yes Figure 4 Schematic cross-sectional view of the middle BB;

[0028] Figure 7 yes Figure 6 A magnified schematic diagram of the middle track;

[0029] Figure 8 This is a schematic diagram of cooling the arch rib;

[0030] Figure numerals: 1—arch rib; 2—reinforcement rod; 3—detection area; 10—movable carrier; 11—three-dimensional scanning device; 12—infrared thermal imager; 13—first bracket; 131—fixed bracket; 132—movable bracket; 133—telescopic mechanism; 14—second bracket; 15—mounting bracket; 16—mounting shaft; 17—drive motor; 18—track; 19—first cooling plate; 110—second cooling plate; 111—flexible delivery pipe; 112—gap; 113—third cooling plate; 114—liquid nitrogen storage tank; 115—delivery pump; 116—delivery pipe; 20—processor. DETAILED DESCRIPTION

[0031] The present invention will be further described below with reference to the accompanying drawings and examples.

[0032] The infrared detection method for arch bridge hollowness of the present invention is as follows: Figure 1 As shown, the following steps are included:

[0033] S1. After concrete is injected into the steel pipe of the arch rib 1, when the concrete strength reaches 70%, the temperature of the surface of the arch rib 1 is adjusted to T1, and then the arch rib 1 is scanned using the three-dimensional scanning device 11 and the infrared thermal imager 12 to obtain a three-dimensional contour map and infrared image of the arch rib 1.

[0034] The surface temperature of the arch rib 1 is adjusted to T1. Specifically, the surface temperature of the arch rib 1 can be increased or decreased, ensuring that the change in the surface temperature of the arch rib 1 is no less than 30°C. By cold excitation or hot excitation of the arch rib 1, an infrared image of the surface of the arch rib 1 is acquired using the infrared thermal imager 12. Based on the infrared image, the temperature changes at various locations on the surface of the arch rib 1 are determined to identify any voids. When a void is discovered, its location is recorded and repaired. If the void area is too large, the arch rib 1 is eliminated, ensuring that all arch ribs 1 meet the relevant design requirements.

[0035] The 3D scanning device 11 can be an existing laser 3D scanner, which can accurately construct a 3D contour image of the arch rib 1. 3D scanning of the arch rib 1 at temperature T1 can avoid dimensional errors caused by thermal expansion and contraction of the arch rib 1 during temperature changes.

[0036] A storage device is used to save the three-dimensional contour map and infrared image.

[0037] S2. After the arch rib 1 and the reinforcing rod 2 are welded, a detection area 3 is determined. The detection area 3 is located around the connection surface between the arch rib 1 and the reinforcing rod 2.

[0038] Figure 2This is a common way of connecting the arch rib 1 and the reinforcing rod 2. The range of the detection area 3 can be determined based on experience. The detection area 3 is located on the circumferential surface of the arch rib 1 so that the contour of the detection area 3 can coincide with the three-dimensional contour map obtained in step S1. The axial distance from the ends of the detection area 3 to the center of the connection surface between the arch rib 1 and the reinforcing rod 2 can be 15 to 20 cm. The detection area 3 is determined as follows: Figure 3 shown.

[0039] S3 , adjusting the temperature of the detection area 3 to T1 , scanning the detection area 3 using a three-dimensional scanning device and an infrared thermal imager to obtain a three-dimensional contour map and an infrared image of the detection area 3 .

[0040] The temperature T1 here is the same as the temperature T1 in step S1 , and the arch rib 1 is three-dimensionally scanned at the same temperature to avoid dimensional errors caused by temperature differences.

[0041] S4. Find the area corresponding to the detection area 3 in the three-dimensional contour map obtained in step S1 as the first reference map, compare the three-dimensional contour map of the detection area 3 with the first reference map, calculate the deformation of the detection area 3, and when the deformation is greater than the set value, re-detect whether the inner side of the connection surface between the arch rib 1 and the reinforcing rod 2 is hollow; determine whether the detection area 3 is hollow based on the infrared image of the detection area 3.

[0042] After arch rib 1 and reinforcing rod 2 are welded, the connection surface between arch rib 1 and reinforcing rod 2 is covered, leaving inspection area 3 around the connection surface exposed. Therefore, infrared imaging can be used to inspect inspection area 3, but infrared imaging cannot be used to inspect the connection surface between arch rib 1 and reinforcing rod 2. After obtaining an infrared image of inspection area 3, it can be directly used to identify whether there is any void within inspection area 3 based on this infrared image.

[0043] Detection area 3 is located on a portion of the surface of arch rib 1, and the three-dimensional contour image obtained in step S1 represents the surface profile of the entire arch rib 1. Therefore, when arch rib 1 is not deformed, detection area 3 completely overlaps with the three-dimensional contour image obtained in step S1. The present invention compares the three-dimensional contour image of detection area 3 after welding with the first reference image of the corresponding position before welding to determine the deformation of detection area 3 after welding. Specifically, the outer diameter of detection area 3 at multiple axial locations can be calculated and compared with the outer diameter of the first reference image to calculate the deformation.

[0044] When the deformation is small, the probability of voiding is small, and when the deformation is large, the probability of voiding is large. Therefore, the set value of the deformation can be obtained through multiple tests. When the deformation is less than the set value, it is determined that there is no voiding on the inner side of the connection surface between the arch rib 1 and the reinforcing rod 2; when the deformation is greater than or equal to the set value, it is determined that there is a greater probability of voiding on the inner side of the connection surface between the arch rib 1 and the reinforcing rod 2, and it is necessary to re-test whether the inner side of the connection surface between the arch rib 1 and the reinforcing rod 2 is voiding.

[0045] Specifically, when the arch rib 1 and the reinforcing rod 2 are welded, the common deformation is radial shrinkage deformation. After many tests, it is shown that when the radial deformation is 0.1%, the probability of voiding is about 18%, and the probability of voiding doubles for every 0.05% increase in radial deformation. Taking all factors into consideration, in the present invention, when the radial deformation of the detection area 3 is greater than 0.1%, the inner side of the connection surface between the arch rib 1 and the reinforcing rod 2 is detected again to see whether there is voiding.

[0046] Specifically, ultrasonic testing is used to detect whether there is any air gap inside the connection surface between the arch rib 1 and the reinforcing rod 2. Ultrasonic testing can penetrate the steel pipe on the surface of the arch rib 1 and directly reach the internal concrete, so it can detect whether there is any air gap inside the connection surface between the arch rib 1 and the reinforcing rod 2.

[0047] Compared with infrared detection alone, the present invention adds deformation detection to the detection area 3, allowing for preliminary detection of whether the inner side of the connection surface between the arch rib 1 and the reinforcing rod 2 is empty. This improves the comprehensiveness of the detection, eliminates detection blind spots, and ensures detection accuracy. Compared with direct ultrasonic detection, infrared detection and three-dimensional profile detection do not require the application of coupling agent to the arch rib surface, requiring less equipment and personnel, making operation more convenient and detection more efficient. The present invention first uses a combination of infrared detection and three-dimensional profile detection for detection. When the inner side of the connection surface between the arch rib 1 and the reinforcing rod 2 has a high probability of being empty, further in-depth detection such as ultrasonic detection is performed, ensuring both detection efficiency and improving detection accuracy.

[0048] In step S4, the area corresponding to the detection area 3 is found in the infrared image obtained in step S1 as the second reference image, and the infrared image of the detection area 3 is compared with the second reference image to find the void area. In both steps S1 and S4, infrared detection is performed at temperature T1. When no void occurs after welding, the infrared image and the second reference image should be consistent. When void occurs after welding, by comparing the infrared image with the second reference image, different areas can be intuitively and quickly found, and these areas are likely to have voids. The present invention can directly determine whether the detection area 3 has voids by comparing the infrared image with the second reference image. Compared with the existing technology, the comparison is more intuitive and more efficient.

[0049] In steps S1 and S3, liquid nitrogen is used to reduce the temperature of the surface of the arch rib 1 to -30°C. Of course, hot water or a heating mechanism can also be used to increase the temperature of the surface of the arch rib 1 to about 60 to 70°C.

[0050] The infrared detection device for arch bridge hollowing used to implement the above-mentioned infrared detection method for arch bridge hollowing is as follows: Figures 4 to 8 As shown, it includes a mobile carrier 10 and a processor 20. The mobile carrier 10 is provided with an infrared thermal imager 12 and a temperature control mechanism. The temperature control mechanism is used to adjust the surface temperature of the arch rib 1. The infrared thermal imager 12 is communicatively connected to the processor 20. The mobile carrier 10 is provided with a three-dimensional scanning device 11. The three-dimensional scanning device 11 is communicatively connected to the processor 20.

[0051] The mobile carrier 10 can move, thereby driving the infrared thermal imager 12, the temperature control mechanism and the three-dimensional scanning device 11 to move, so that the temperature control mechanism completes the cooling of the surface of the arch rib 1, and the infrared thermal imager 12 and the three-dimensional scanning device 11 complete the scanning of the arch rib 1. The processor 20 can be set on the mobile carrier 10, or it can be set separately. The infrared thermal imager 12 and the three-dimensional scanning device 11 can be connected to the processor 20 through wireless communication. The processor 20 is provided with three-dimensional modeling software and infrared image processing software, which can use existing technologies. The infrared thermal imager 12 and the three-dimensional scanning device 11 transmit the scanning results to the processor 20, and the processor 20 establishes a three-dimensional contour map of the arch rib 1 and recognizes the infrared image.

[0052] In step S1, the preparation of the arch rib 1 is carried out on the ground, so the mobile carrier 10 can adopt various existing ground mobile vehicle structures. Step S3 is carried out after the construction of the arch rib 1, and high-altitude work is required. At this time, the mobile carrier 10 is a heavy-load drone, and the main body of the heavy-load drone can adopt existing technology. Figure 4 and Figure 5 As shown, a first bracket 13 and a second bracket 14 are provided on either side of the heavy-load drone, with the temperature control mechanism mounted on the first bracket 13. A mounting bracket 15 is provided at the end of the second bracket 14. Both ends of the mounting bracket 15 are mounted to the mounting bracket 15 via mounting shafts 16, which are connected to drive motors 17. The 3D scanning device 11 and the infrared thermal imager 12 are both mounted on the mounting bracket 15.

[0053] During inspection, the temperature of inspection area 3 is first adjusted to T1 using a temperature control mechanism. The heavy-duty drone then drives the second bracket 14 to move above the arch rib 1. With the scanning heads of the three-dimensional scanning device 11 and the infrared thermal imager 12 facing downward, the inspection area 3 can be scanned. During scanning, the drive motor 17 can be used to rotate the mounting shaft 16, mounting bracket 15, three-dimensional scanning device 11, and infrared thermal imager 12 as a whole. Simultaneously, the heavy-duty drone drives the second bracket 14 gradually from the arch rib 1 to the side of the arch rib 1, and finally to the bottom of the arch rib 1. The overall movement of the heavy-duty drone, combined with the rotation of the mounting bracket 15, ensures that the three-dimensional scanning device 11 and infrared thermal imager 12 can scan the entire circumference of the inspection area 3. The processor 20 can be located on the ground to reduce the weight of the heavy-duty drone. The three-dimensional scanning device 11 and infrared thermal imager 12 transmit data to the processor 20 via a 4G network, for example.

[0054] The temperature control mechanism can be a cooling mechanism or a heating mechanism. The present invention adopts a cooling mechanism. Currently, liquid nitrogen is generally used for cooling. When cooling, the liquid nitrogen is sprayed toward the arch rib 1. Various existing cooling mechanisms usually only spray liquid nitrogen in one direction and cannot spray the entire circumference of the arch rib 1 uniformly at the same time. This easily leads to uneven cooling, thereby affecting the accuracy of infrared detection.

[0055] In order to ensure that the detection area 3 can be sprayed uniformly in the circumferential direction, as shown in FIG. Figure 6 and Figure 7As shown, the mobile carrier 10 of the present invention is connected to an arc-shaped track 18, which is 1 / 2 circle. The track 18 is provided with an arc-shaped first cooling plate 19, an arc-shaped second cooling plate 110, and an arc-shaped third cooling plate 113. The third cooling plate 113 is 1 / 2 circle, and the inner diameter of the third cooling plate 113 is larger than the outer diameter of the arch rib 1. The lengths of the first cooling plate 19 and the second cooling plate 110 are both slightly larger than 1 / 4 circle. The first cooling plate 19 and the second cooling plate 110 are both slidably matched with the track 18, that is, the first cooling plate 19 and the second cooling plate 110 can slide along the track 18, and the sliding trajectory is an arc. The third cooling plate 113 is fixedly connected to the inner side of the track 18 and its position remains unchanged. The first cooling plate 19, the second cooling plate 110, and the third cooling plate 113 are all hollow plates. An arc-shaped flexible conveying tube 111 is provided between the first cooling plate 19 and the second cooling plate 110. The flexible conveying tube 111 is made of an airtight membrane with a certain strength and a small thickness. When the gas inside the flexible conveying tube 111 is extracted, the flexible conveying tube 111 can fully shrink, and the shrinking volume is very small, occupying a very small space. The middle part of the flexible conveying tube 111 is fixedly connected to the track 18. The two ends of the flexible conveying tube 111 are connected to the inner cavity of the first cooling plate 19 and the second cooling plate 110 respectively through a one-way valve. The one-way valve conducts from the flexible conveying tube 111 to the first cooling plate 19 and the second cooling plate 110, so that the gas in the flexible conveying tube 111 can enter the first cooling plate 19 and the second cooling plate 110, while the gas in the first cooling plate 19 and the second cooling plate 110 cannot enter the flexible conveying tube 111. The first and second cooling plates 19, 110 are provided with a semicircular notch 112 at one end away from the flexible delivery tube 111. The diameter of the notch 112 is larger than the diameter of the reinforcing rod 2. The notches 112 on the first and second cooling plates 19, 110 can form a circular hole for accommodating the reinforcing rod 2. The first, second, and third cooling plates 19, 110, 113 form a circular cooling cavity. This circular cavity is not a standard circle. The inner diameters of the first and second cooling plates 19, 110, 110 are larger than the inner diameter of the third cooling plate 113. The inner surfaces of the first, second, and third cooling plates 19, 110, 113 are provided with spray holes for spraying liquid nitrogen. The temperature control mechanism includes a liquid nitrogen storage tank 114 for storing liquid nitrogen. The liquid nitrogen storage tank 114 is connected to a delivery pump 115 for discharging liquid nitrogen. The delivery pump 115 communicates with the flexible delivery tube 111 and the inner cavity of the third cooling plate 113 via a flexible delivery tube 116.

[0056] When the temperature control mechanism is not working, the flexible conveying tube 111 is in a contracted state and its volume is small. The first cooling plate 19 and the second cooling plate 110 are both located in the track 18, and the cooling cavity is in an open state. When the detection area 3 needs to be cooled, the mobile carrier 10 drives the track 18 to move to one side of the detection area 3. When the opening of the cooling cavity is aligned with the arch rib 1, the track 18 is driven to move an appropriate distance toward the arch rib 1 so that the arch rib 1 enters the cooling cavity. Then the delivery pump 115 is started. The delivery pump 115 delivers the liquid nitrogen in the liquid nitrogen storage tank 114 to the inner cavity of the third cooling plate 113 and the flexible delivery pipe 111. The liquid nitrogen in the inner cavity of the third cooling plate 113 is sprayed from the spray hole to the arch rib 1 to cool the arch rib 1; and the liquid nitrogen in the flexible delivery pipe 111 is vaporized and fills the flexible delivery pipe 111, causing the flexible delivery pipe 111 to expand axially, thereby pushing the first cooling plate 19 and the second cooling plate 110 to slide toward the outside of the track 18, so that the ends of the first cooling plate 19 and the second cooling plate 110 are in contact, and the notches 112 on the first cooling plate 19 and the second cooling plate 110 surround the reinforcing rod 2. Figure 8 At the same time, the liquid nitrogen in the flexible delivery pipe 111 enters the inner cavity of the first cooling plate 19 and the second cooling plate 110 through the one-way valve, and is sprayed toward the arch rib 1 through the spray hole.

[0057] The first cooling plate 19, the second cooling plate 110 and the third cooling plate 113 form a circular cooling cavity, and simultaneously spray liquid nitrogen (or low-temperature nitrogen gas after liquid nitrogen vaporization) toward the arch rib 1, which can uniformly cool the entire circumference of the arch rib 1 at the same time to ensure the accuracy of infrared detection.

[0058] The delivery pump 115 is a reciprocating pump. After the arch rib 1 cools to a set temperature, the delivery pump 115 operates in reverse to extract the gas in the flexible delivery tube 111, causing the flexible delivery tube 111 to contract axially, pulling the first cooling plate 19 and the second cooling plate 110 back into the track 18, reopening the cooling chamber. The mobile carrier 10 then drives the track 18 away from the arch rib 1. Alternatively, another vacuum pump connected to the flexible delivery tube 111 can be used to extract and empty the gas inside the flexible delivery tube 111.

[0059] In the present invention, the liquid nitrogen storage tank 114 and the like are mounted on the first bracket 13. As the liquid nitrogen is consumed, the weight of the liquid nitrogen storage tank 114 gradually decreases, causing the overall center of gravity of the heavy-loaded drone to shift. To facilitate adjustment of the center of gravity of the heavy-loaded drone, the first bracket 13 and the second bracket 14 are both arranged horizontally. The first bracket 13 includes a fixed frame 131 and a movable frame 132. The fixed frame 131 is fixedly connected to the heavy-loaded drone, and the movable frame 132 slides horizontally with the fixed frame 131. The movable frame 132 is connected to a telescopic mechanism 133, which can be a linear motor or other device. A temperature control mechanism is mounted on the movable frame 132. When the weight of the liquid nitrogen storage tank 114 decreases after consumption, the telescopic mechanism 133 extends, pushing the movable frame 132 to move an appropriate distance away from the main body of the heavy-loaded drone, thereby maintaining the overall center of gravity of the heavy-loaded drone unchanged and improving flight stability.

[0060] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. The infrared detection method for arch bridge hollowing is characterized by: The following steps are involved: S1, after concrete is injected into the steel pipe of the arch rib (1), when the concrete strength reaches 70%, the temperature of the surface of the arch rib (1) is adjusted to T1, and then the arch rib (1) is scanned using a three-dimensional scanning device (11) and an infrared thermal imager (12) to obtain a three-dimensional contour map and an infrared image of the arch rib (1); S2. After the arch rib (1) and the reinforcing rod (2) are welded, a detection area (3) is determined. The detection area (3) is located around the connection surface between the arch rib (1) and the reinforcing rod (2); S3, adjusting the temperature of the detection area (3) to T1, scanning the detection area (3) using a three-dimensional scanning device and an infrared thermal imager, and obtaining a three-dimensional contour map and an infrared image of the detection area (3); S4. Finding an area corresponding to the detection area (3) in the three-dimensional contour image obtained in step S1 as a first reference image, comparing the three-dimensional contour image of the detection area (3) with the first reference image, calculating the deformation of the detection area (3), and when the deformation is greater than a set value, re-detecting whether the inner side of the connection surface between the arch rib (1) and the reinforcing rod (2) is hollow; judging whether the detection area (3) is hollow based on the infrared image of the detection area (3).

2. The infrared detection method for arch bridge voids according to claim 1, wherein: In step S4, when the radial deformation of the detection area (3) is greater than 0.1%, the inner side of the connection surface between the arch rib (1) and the reinforcing rod (2) is detected again to see if there is any air gap.

3. The infrared detection method for arch bridge voids according to claim 1, wherein: In step S4, when the deformation amount is greater than the set value, ultrasonic waves are used to detect again whether the inner side of the connection surface between the arch rib (1) and the reinforcing rod (2) is empty.

4. The infrared detection method for arch bridge voids according to claim 1, wherein: In step S4, the area corresponding to the detection area (3) is found in the infrared image obtained in step S1 as a second reference image, and the infrared image of the detection area (3) is compared with the second reference image to find the empty area.

5. The infrared detection method for arch bridge voids according to claim 1, wherein: In steps S1 and S3, liquid nitrogen is used to reduce the surface temperature of the arch rib (1) to -30°C.

6. An infrared detection device for arch bridge hollowing for implementing the infrared detection method for arch bridge hollowing according to claim 1, comprising a mobile carrier (10) and a processor (20), wherein the mobile carrier (10) is provided with an infrared thermal imager (12) and a temperature control mechanism, and the infrared thermal imager (12) is communicatively connected to the processor (20), characterized in that: A three-dimensional scanning device (11) is provided on the mobile carrier (10), and the three-dimensional scanning device (11) is communicatively connected to the processor (20).

7. The infrared detection device for arch bridge voids according to claim 6, characterized in that: The mobile carrier (10) is a heavy-loaded unmanned aerial vehicle (UAV), and a first bracket (13) and a second bracket (14) are respectively provided on both sides of the heavy-loaded UAV. The temperature control mechanism is installed on the first bracket (13), and a mounting frame (15) is provided at the end of the second bracket (14). Both ends of the mounting frame (15) are installed on the mounting frame (15) through a mounting shaft (16), and the mounting shaft (16) is connected to a driving motor (17); the three-dimensional scanning device (11) and the infrared thermal imager (12) are both installed on the mounting frame (15).

8. The infrared detection device for arch bridge voids according to claim 6 or 7, characterized in that: The mobile carrier (10) is connected to an arc-shaped track (18), and an arc-shaped first cooling plate (19), an arc-shaped second cooling plate (110) and an arc-shaped third cooling plate (113) are provided on the track (18). The first cooling plate (19) and the second cooling plate (110) are both slidably matched with the track (18), and the third cooling plate (113) is fixedly connected to the inner side of the track (18). The first cooling plate (19), the second cooling plate (110) and the third cooling plate (113) are all hollow plates. An arc-shaped flexible conveying pipe (111) is provided between the first cooling plate (19) and the second cooling plate (110), and both ends of the flexible conveying pipe (111) are connected to the first cooling plate (19) and the second cooling plate (110) through a one-way valve. 19) and the inner cavity of the second cooling plate (110), a semicircular notch (112) is provided at one end of the first cooling plate (19) and the second cooling plate (110) away from the flexible delivery tube (111), the first cooling plate (19), the second cooling plate (110) and the third cooling plate (113) form a circular cooling cavity, and the inner side surfaces of the first cooling plate (19), the second cooling plate (110) and the third cooling plate (113) are provided with injection holes; the temperature control mechanism includes a liquid nitrogen storage tank (114), the liquid nitrogen storage tank (114) is connected to a delivery pump (115), and the delivery pump (115) is connected to the flexible delivery tube (111) and the inner cavity of the third cooling plate (113) through a flexible delivery tube (116).

9. The infrared detection device for arch bridge voids according to claim 7, characterized in that: The first bracket (13) and the second bracket (14) are both arranged horizontally. The first bracket (13) includes a fixed bracket (131) and a movable bracket (132). The fixed bracket (131) is fixedly connected to the heavy-load drone. The movable bracket (132) and the fixed bracket (131) are slidably matched in the horizontal direction. The movable bracket (132) is connected to a telescopic mechanism (133). The temperature control mechanism is installed on the movable bracket (132).

Images