Ultrasonic nondestructive testing method and device for compactness of concrete in steel pipe

Abstract

The invention relates to an ultrasonic nondestructive testing method and device for compactness of concrete in a steel pipe, and the method comprises the following steps: (1) calibrating a testing area on the outer wall of the steel pipe, and installing an auxiliary device to realize precise positioning of a planar transducer array; (2) starting the ultrasonic detector, connecting the planar transducer and calibrating zero sound time; (3) setting engineering parameters, smearing a coupling agent and sampling point by point; and (4) exporting the data to compactness visualization software, and generating a two-dimensional compactness and void height distribution diagram of which the resolution is greater than or equal to 1ppi. The device comprises an ultrasonic detection machine, an auxiliary device and compactness visualization software, the detection machine is composed of an ultrasonic detector, a planar transducer and a signal line, and the auxiliary device is designed by means of modular assembly of special-shaped rubber strong soft magnetic strips and adapts to different pipe diameters; visual software realizes void area identification and height quantification based on a space coding imaging technology. The method breaks through the limitation of traditional single-point detection, the detection error is smaller than or equal to + / -12mm, the measurement point layout efficiency is improved by 80%, and nondestructive quality evaluation and dynamic monitoring of the concrete filled steel tube in the high-altitude complex environment are supported.

Description

Technical Field

[0001] The present invention relates to the technical field of nondestructive testing of steel tube concrete, and in particular to an ultrasonic nondestructive testing method and device for the density of concrete in a steel tube, which is suitable for construction quality monitoring and service performance evaluation of steel tube concrete structures. Background Art

[0002] Due to its excellent load-bearing capacity and durability, concrete-filled steel tube (CFST) structures have become the preferred bridge type for long-span railway arch bridges in high-altitude, deep canyon regions. However, in the complex high-altitude environment characterized by low air pressure, large temperature fluctuations, and harsh transportation conditions, CFST is susceptible to quality issues such as voids and debonding due to defects in the pouring process or fluctuations in material properties, seriously compromising structural safety. Therefore, the development of efficient and accurate density testing technology is crucial to ensuring project quality and bridge durability.

[0003] At present, the density of steel tube concrete is mainly tested by three methods: core sampling, manual tapping, and ultrasonic non-destructive testing. The core sampling method directly observes the state of the interface between concrete and steel pipe and measures the void height by drilling core samples. Although it is intuitive and reliable, it is a destructive test that may damage the integrity of the structure and cannot fully evaluate the overall density. The manual tapping method qualitatively determines the location of the defect by the tapping sound, but its accuracy depends on the operator's experience and cannot quantitatively analyze the void height or density distribution. The ultrasonic non-destructive testing method evaluates the density of concrete by measuring ultrasonic parameters, but most existing detection devices use a single-point excitation-single-point reception mode, which can only realize local one-dimensional void height calculation and cannot perform two-dimensional spatial characterization of the area and position of the void area. In addition, traditional ultrasonic equipment is not adaptable enough in high-altitude and low-pressure environments, and the positioning accuracy of the planar transducer is low, which makes the test results susceptible to environmental interference.

[0004] The core problems of existing technologies are mainly reflected in the following three aspects: First, the detection dimension is limited. The single-point detection mode cannot cover the entire area of ​​defects in complex structures and cannot generate a two-dimensional density distribution map, resulting in an incomplete assessment of engineering hazards. Second, the environmental adaptability is poor. The high altitude and low air pressure environment significantly affect the propagation characteristics of ultrasonic waves. The existing equipment is not optimized for such complex conditions, resulting in reduced detection accuracy. Finally, the operating efficiency is low. The traditional equipment lacks modular design, the installation is cumbersome, and it is difficult to achieve rapid layout of multiple measurement points. The detection cycle is long. These problems have seriously restricted the application effect and efficiency of existing technologies in actual projects.

[0005] In view of this, there is an urgent need to develop a non-destructive, high-precision, two-dimensional visualization detection device and method to overcome the limitations of existing technologies and meet the quality control needs of large-span steel tube concrete arch bridges in complex environments at high altitudes. Summary of the Invention

[0006] To overcome the limitations of existing technologies, specifically addressing the problems of single detection dimension, inability to accurately characterize two-dimensional defects, lack of adaptability in high-altitude environments resulting in a significant decrease in detection accuracy, low operational efficiency, and difficulty in achieving efficient deployment of multiple measurement points, and to meet the comprehensive needs of steel tube concrete testing in various environments, ensure the accuracy, precision, and engineering practicality of testing, and provide strong technical support for steel tube concrete quality assessment, one of the objectives of the present invention is to provide a method for ultrasonic non-destructive testing of concrete density in steel tubes.

[0007] The second purpose is to provide a device used in the ultrasonic non-destructive testing method for the density of concrete in a steel pipe.

[0008] The present invention achieves the above-mentioned object through the following technical solution: A method for ultrasonic nondestructive testing of the density of concrete in a steel pipe comprises the following steps:

[0009] (1) Carry out ultrasonic measurement grid calibration in the preset area on the outer wall surface of the steel pipe to be measured, and locate and install the adjustable modular soft magnetic strip array auxiliary device to achieve precise positioning of the planar transducer array;

[0010] (2) Start the ultrasonic detector, use the quick-release rotating bayonet connector to achieve mechanical locking and electrical conduction between the planar transducer and the signal line, and connect the output end of the signal line to the high-frequency signal channel interface of the detector. Then align the two ends of the planar transducer to start zero-sound calibration and save the calibration results;

[0011] (3) Enter the parameter setting interface and set the project parameters, including but not limited to the project name, component name, distance setting, and the number of rows and columns of measuring points in the measuring area. Use coupling agent to tightly couple the planar transducer to the first measuring point position in the measuring area on both sides of the steel tube concrete component; perform the sampling operation, and adjust it automatically or manually to ensure that the initial waveform of the first measuring point is clearly displayed on the instrument display, and then trigger the save function key to store the data of the measuring point; then, synchronously migrate the planar transducers on both sides to the next adjacent measuring point, and use coupling agent again to ensure good coupling, perform a new round of sampling, make necessary adjustments to the acquired waveform, and trigger the save function key again to record the data after the waveform meets the preset standard; repeat this process until all preset measuring points in the measuring area are tested;

[0012] (4) After the test is completed, insert the U disk or removable storage device into the USB port of the ultrasonic detector to export the acquired ultrasonic test data; then connect the U disk or removable storage device to the computer and start the density visualization software; in the density visualization software, load the exported ultrasonic data file and use the integrated spatial coding imaging algorithm to comprehensively analyze and process the ultrasonic data; finally, generate a two-dimensional visualization image for characterizing the density of concrete in the steel pipe and a clear representation image of the void height.

[0013] The auxiliary device adopts a modular assembly design of strong soft magnetic strips of heterosexual rubber or a lightweight steel plate design with the same curvature as the steel pipe. The soft magnetic strips have double-sided magnetic properties and can be flexibly assembled according to the diameters of different steel pipes. Through the preset sequential excitation point layout and combined with magnetic fixation technology, precise control of the spacing between multiple measuring points can be achieved.

[0014] The density visualization software integrates a spatial coding imaging algorithm, analyzes and processes the measured data through thin plate spline interpolation and color partition rendering technology, and outputs a two-dimensional density distribution map and void height representation image with a resolution of ≥1ppi. It can intuitively display the defect boundary, density and void height, and supports dynamic calculation of void height.

[0015] The dynamic calculation of the clearance height is based on the following formula:

[0016]

[0017]

[0018] Where, is the overall ultrasonic velocity of concrete-filled steel tube, m / s; 、 are the ultrasonic velocities of concrete and steel pipe in pipe, m / s; is the outer diameter of the concrete-filled steel tube, mm; When the first wave sound ; b is the wall thickness of the steel pipe, mm; is the inner radius of the steel pipe, mm; is the clearance height, mm.

[0019] The ultrasonic detection machine is suitable for detection in the sound speed range of 1000m / s to 8000m / s. Through the directional transmission and reception of high-frequency electrical signals, it significantly improves the propagation stability and data reliability of ultrasonic waves in complex high-altitude environments. It analyzes parameters in real time, such as the first wave sound time, amplitude attenuation and waveform distortion, to achieve low-error quantitative calculation of the airborne height, so that the error between the detection value and the actual value is maintained at ±12mm.

[0020] The device for ultrasonic nondestructive testing of the density of concrete in a steel pipe comprises:

[0021] An ultrasonic testing machine, comprising an ultrasonic detector, a planar transducer, and a signal line, wherein the signal line is connected to the planar transducer interface on the ultrasonic detector, and the planar transducer and the signal line are detachably connected via a matching quick-release rotating bayonet connector;

[0022] Auxiliary devices, using modular assembly design of strong soft magnetic strips of heterogeneous rubber or lightweight steel plates with the same curvature as the steel pipe, are used to achieve precise positioning of the transducer array;

[0023] The density visualization software integrates a spatially coded imaging algorithm to analyze and process ultrasonic testing data and generate a two-dimensional density distribution map and void height representation image.

[0024] The dimensions of the auxiliary device are 480 mm in length and 340 mm in width, with a distance of 25 mm between the two measuring points and a total weight of ≤2 kg. It can quickly adapt to steel pipes of different diameters from 0.3 m to 3 m, and the installation time is shortened to within 10 minutes.

[0025] The density visualization software converts the serial ultrasonic excitation data into a two-dimensional distribution map of the density of steel tube concrete through thin plate spline interpolation and color partition rendering technology. The blue to red gradient represents the density of 0-100%, and the area, boundary and defect density of the void area are intuitively displayed. The resolution of the two-dimensional surface defect image inside the steel tube concrete is ≥1ppi.

[0026] The beneficial effects of the present invention are:

[0027] 1. The present invention adopts an ultrasonic detector that integrates a high-precision ultrasonic planar transducer and a dedicated signal transmission cable, and is suitable for detection in the sound speed range of 1000m / s to 8000m / s. The device significantly improves the propagation stability and data reliability of ultrasonic waves in complex high-altitude environments through directional transmission and reception of high-frequency electrical signals. Compared with traditional single-point excitation equipment, its signal processing module analyzes ultrasonic parameters in real time, such as first-wave acoustic time, amplitude attenuation, and waveform distortion, to achieve low-error quantitative calculation of the air gap height, greatly improving detection accuracy, and maintaining the error between the detection value and the actual value at ±12mm.

[0028] 2. The auxiliary device utilizes a modular assembly design with powerful magnets or lightweight metal or steel plates, enabling rapid adaptation to pipes of varying diameters. The device's pre-set sequential excitation point layout, combined with magnetic fixation technology, allows for precise control of the spacing between multiple measuring points. Installation time is reduced to under 10 minutes, increasing efficiency by 80% compared to traditional manual positioning and inspection. Furthermore, the lightweight design (total weight ≤ 2kg) significantly reduces operational effort, making it particularly suitable for use in confined spaces and at height.

[0029] 3. Density visualization software, based on a spatially encoded imaging algorithm, converts sequential ultrasonic excitation data into a two-dimensional density distribution map of the CFST. Using thin-plate spline interpolation and color-coded rendering technology (with a blue to red gradient representing density from 0-100%), it intuitively displays the area, boundaries, and density of voids within the CFST. The 2D surface defect images within the CFST have a resolution of ≥1 ppi. Compared to traditional one-dimensional inspection reports, this software reduces missed detections by 90% and provides precise spatial positioning for remedial engineering measures.

[0030] 4. The detection method described in this invention integrates sequential ultrasonic excitation, a multi-factor calibration model (including compensation for air pressure, water-binder ratio, and aggregate proportion), and dynamic calculation of void height, breaking through the dimensional limitations of traditional single-point detection. By presetting detection ages and testing in different time periods, it effectively mitigates interference from temperature fluctuations and enables dynamic monitoring of density throughout the entire lifecycle. This method covers critical areas such as the arch crown, arch foot, and welds, increasing detection efficiency by 50%, making it suitable for the extreme conditions found in the complex, high-altitude environments of the Sichuan-Tibet Railway.

[0031] 5. Targeting the complex environments of high altitudes, this invention incorporates a windproof and shockproof packaging design to ensure stable operation within a temperature range of -20°C to 50°C, with a data repeatability error of ≤2%. Through non-destructive testing, modular device reuse (with an auxiliary device lifespan of ≥5 years), and automated data processing, this invention reduces the cost of a single test by 40%. This provides a standardized solution for quality control of long-span concrete-filled steel tube arch bridges in complex high-altitude environments, with significant socioeconomic benefits and potential for industry adoption. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a schematic structural diagram of the ultrasonic nondestructive testing device for density of concrete in a steel pipe according to the present invention;

[0033] Figure 2 is a schematic diagram of the ultrasonic testing machine of the present invention;

[0034] Figure 3 A schematic diagram of the auxiliary device (lightweight steel plate) of the present invention;

[0035] Figure 4 A schematic diagram of the auxiliary device (magnetic module) of the present invention;

[0036] Figure 5 Schematic diagram of the density visualization software of the present invention;

[0037] Figure 6 This is a schematic diagram of the operation process of ultrasonic non-destructive testing of density of concrete in steel pipes according to the present invention;

[0038] Figure 7Schematic diagrams of four hypothetical propagation paths of ultrasonic waves in steel tube concrete;

[0039] Figure 8 Schematic diagram of the measurement point arrangement on the outer wall of steel tube concrete component.

[0040] In the figure, 1. Steel tube concrete specimen, 2. Auxiliary device, 3. Planar transducer, 4. Signal line, 5. Ultrasonic detector, 6. Power supply, 7. Charging port, 8. USB port, 9. High-frequency signal channel interface, 10. Ultrasonic non-destructive testing control interface, 11. Density visualization software. DETAILED DESCRIPTION

[0041] The technical solutions of the present invention are further described in detail below through accompanying drawings and examples. Unless otherwise specified, the technical and scientific terms used herein conform to the common understanding of professionals in the field of the present invention and industry standards. The terms used in this specification are intended to describe the embodiments and are not intended to limit the scope of protection of the present invention.

[0042] Example 1

[0043] The ultrasonic nondestructive testing device for concrete in steel pipes of the present invention comprises an ultrasonic detector 5, a signal line 4, a planar transducer 3, an auxiliary device 2, and density visualization software 11. Its structure and connection relationship are as follows:

[0044] The ultrasonic detector 5, serving as the core device, is equipped with a high-frequency signal channel interface 9 for connecting to one end of a signal cable 4. The other end of the signal cable 4 is tightly connected to the planar transducer 3 via a quick-release rotating bayonet connector, ensuring stable and reliable signal transmission. The planar transducer 3 is responsible for transmitting and receiving ultrasonic waves and is a key component for detection.

[0045] The auxiliary device 2 is installed within the outer wall measurement area of ​​the concrete-filled steel tube specimen 1. Its installation position must be strictly symmetrical with the central axis of the concrete-filled steel tube specimen 1, and the auxiliary devices 2 on both sides must be kept at the same height. This installation requirement ensures that the two planar transducers 3 can be accurately aligned and measured, thereby improving the accuracy and reliability of the detection.

[0046] The ultrasonic detector 5 is provided with a power supply 6 for starting and stopping the device. When the ultrasonic detector 5 is low on power, it can be charged immediately by connecting the charger to the charging port 7. During the charging process, the device can still perform the detection work normally, ensuring the continuity and efficiency of the detection.

[0047] Before using the ultrasonic detector 5 for testing, a zeroing operation is required. Specifically, the two planar transducers 3 are properly aligned, and then sampling is performed according to the prompts on the ultrasonic detector 5 interface to determine the zero sound time. Completing the zeroing operation provides an accurate benchmark for subsequent ultrasonic nondestructive testing.

[0048] After zeroing is completed, the ultrasonic nondestructive testing control interface 10 is entered. On this interface, project parameters are set, including but not limited to the project name, component name, distance setting, and the number of rows and columns of measuring points in the measurement area, to distinguish different testing times and testing areas, and facilitate subsequent retrieval and management of ultrasonic data.

[0049] A coupling agent is used to tightly couple the planar transducers 3 to the first measuring point position in the measuring area on both sides of the steel tube concrete component 1; the sampling operation of the ultrasonic non-destructive testing control interface 10 is executed, and the initial waveform of the first measuring point is clearly displayed on the ultrasonic non-destructive testing control interface 10 through automatic or manual adjustment, and then the save function key is triggered to store the data of the measuring point, including the sound time, wave velocity, amplitude and waveform; then, the planar transducers 3 on both sides are synchronously moved to the next adjacent measuring point, and the coupling agent is used again to ensure good coupling, and a new round of sampling is carried out. The necessary adjustments are made to the acquired waveforms. After the waveforms meet the preset standards, the save function key is triggered again to record the data; this process is repeated until all preset measuring points in the measuring area are tested.

[0050] After testing, the data is exported from the USB port 8 of the ultrasonic detector 5 via a USB flash drive or removable disk. The exported data is directly uploaded to the density visualization software 11 for processing and analysis. This software generates a two-dimensional surface-shaped image of the internal defects of the CFST, i.e., the height of the voids, with a resolution of ≥1 ppi. This allows for a visual display of the locations of voids and defects in the CFST, facilitating timely detection and repair or reinforcement of defective areas by inspectors.

[0051] Example 2

[0052] The apparatus used in the ultrasonic nondestructive testing method for the density of concrete in steel tubes described herein comprises an ultrasonic detector 5, an auxiliary device 2, and density visualization software 11. The ultrasonic detector 5, as the core, is connected to the planar transducer 3 via a signal line 4, enabling directional transmission and reception of ultrasonic waves. The auxiliary device 2 utilizes a modular assembly design with powerful magnets or lightweight steel plates with uniform curvature, enabling rapid adaptation to steel tube concrete components of varying diameters and ensuring accurate alignment of the planar transducer during testing. The density visualization software 11 integrates a spatially encoded imaging algorithm and applies a thin plate spline method to spatially interpolate this data, generating a two-dimensional distribution map of the ultrasonic velocity of the steel tube concrete in the measured area and an image representation of the void height. These maps are then displayed based on color zoning principles. Blue areas (higher wave velocity) reflect good bonding at the steel tube concrete interface, while red areas (lower wave velocity) indicate potential bonding defects. Color contrast visually presents the density distribution characteristics.

[0053] Technical principle:

[0054] First, the propagation characteristics of ultrasonic waves in steel tube concrete, especially the reflection, refraction and transmission phenomena generated when encountering defects, cause the received ultrasonic signal parameters (such as first wave time, amplitude, and frequency) to change. By analyzing the first wave time change through the first wave acoustic time method, the location and size of the defect can be determined. Because ultrasonic waves have the characteristic of different propagation speeds in different media, if the concrete is dense, the ultrasonic waves will propagate radially along the diameter of the steel tube concrete, with the shortest propagation path, the maximum wave speed, and the minimum acoustic time; if there are defects in the concrete, the propagation path of the ultrasonic waves will change, which will cause the detection acoustic time to increase compared to the dense case. Therefore, the acoustic time is usually used as an important basis for judging whether there are boundary defects in steel tube concrete. When the steel tube concrete is dense, the ultrasonic waves propagate radially along the diameter of the steel tube concrete. Figure 7 (a) The propagation path is the shortest, the speed is the fastest, and the acoustic time is the smallest. If there is a boundary void defect in the steel tube concrete, the propagation path of the ultrasonic wave is more complicated and can be roughly divided into the following possible situations: ① Directly pass through the defect and propagate radially to reach the receiver Figure 7 (b); ② It propagates along the pipe wall first, reaches the dense area, and then passes through the concrete to reach the receiver (Figure 7 (c); ③ It propagates along the pipe wall throughout the entire process without passing through the concrete (Figure 7 (d)).

[0055] Compared with the dense situation, no matter which propagation path is used, the detection acoustic time will eventually be larger. Therefore, the acoustic time is usually used as the main basis for judging whether there are boundary defects and void defects in steel tube concrete. However, the location of the internal void and the size of the defect cannot be explained by the acoustic time data alone. Therefore, it is still necessary to explore and determine the propagation path of the ultrasonic wave in the case of voids in steel tube concrete to further accurately calculate the void location and defect size. The first wave acoustic time calculation formulas for the four propagation paths of ultrasonic waves in steel tube concrete, namely, linear propagation in the dense case of steel tube concrete, propagation through defects in the void state, propagation around defects, and propagation along the pipe wall, are as follows (1) (2) (3) (4), which correspond to Figure 7 (a), (b), (c), (d):

[0056] #timg# (1) #timg# (2) #timg# (3) #timg# (4)

[0057] Where, b is the wall thickness of the steel pipe; D is the outer diameter of the steel pipe; H is the hollow height, mm; 、 and are the speeds of ultrasonic waves in steel pipes, concrete, and air, m / s; is the arc length between point A and point B, such as Figure 7 (c) shown, mm; is the straight-line distance from point B to point A', mm.

[0058] In addition, through the sequential excitation point layout of the auxiliary device 2 and the spatial encoding imaging algorithm of the density visualization software 11, synchronous or efficient sequential detection of multiple measuring points and two-dimensional visualization of the internal density of the steel tube concrete and the characterization of the void height are achieved. The dynamic calculation of the void height is calculated using Equations (5) and (6).

[0059] (5)

[0060] (6)

[0061] Where, is the overall ultrasonic velocity of concrete-filled steel tube, m / s; 、 are the ultrasonic velocities of concrete and steel pipe in pipe, m / s; is the outer diameter of the concrete-filled steel tube, mm; When the first wave sound ; is the wall thickness of the steel pipe, mm; is the inner radius of the steel pipe, mm; is the clearance height, mm.

[0062] Example 3

[0063] This embodiment is the ultrasonic nondestructive testing method for the density of concrete in a steel pipe, including the following steps:

[0064] (1) Carry out ultrasonic measurement grid calibration in a preset area on the outer wall surface of the steel tube concrete component 1 to be measured, and position and install the adjustable modular soft magnetic strip array auxiliary device 2 to achieve precise positioning of the transducer array;

[0065] (2) Start the ultrasonic detector 5, and mechanically lock and electrically connect the planar transducer 3 and the signal line 4 through the quick-release rotating bayonet connector, and connect the output end of the signal line 4 to the high-frequency signal channel interface 9 of the detector. Then, align the two ends of the planar transducer 3 to start calibrating the zero sound, and save the calibration results;

[0066] (3) Enter the parameter setting interface and set the project parameters, including but not limited to the project name, component name, distance setting, and the number of rows and columns of measuring points in the measuring area. Use coupling agent to tightly couple the planar transducer 3 to the first measuring point position in the measuring area on both sides of the steel tube concrete component 1; perform the sampling operation, and adjust it automatically or manually to ensure that the initial waveform of the first measuring point is clearly displayed on the instrument display, and then trigger the save function key to store the data of the measuring point; then, synchronously migrate the planar transducers 3 on both sides to the next adjacent measuring point, and use coupling agent again to ensure good coupling, perform a new round of sampling, make necessary adjustments to the acquired waveform, and trigger the save function key again to record the data after the waveform meets the preset standard; repeat this process until all preset measuring points in the measuring area are tested.

[0067] (4) After the test is completed, insert the USB flash drive or removable storage device into the USB interface 8 of the ultrasonic detector 5 to export the acquired ultrasonic test data; then, connect the USB flash drive or removable storage device to the computer and start the density visualization software 11; in the density visualization software 11, load the exported ultrasonic data file, and use the integrated spatial encoding imaging algorithm to comprehensively analyze and process the ultrasonic data; finally, generate a two-dimensional visualization image for characterizing the density of the concrete in the steel pipe and a clear representation image of the void height.

[0068] According to the ultrasonic nondestructive testing method and supporting device for density of steel tube concrete of the present invention, a steel tube concrete component with a preset void defect was prepared in the experiment (specific parameters are shown in Table 1), the maximum void height was set to 30 mm, and a special ultrasonic coupling auxiliary device was fixedly installed on the outer wall of the component (specific structural dimensions are shown in Table 1). Figure 4 In the experiment, C70 high-strength concrete was used for pouring, and its mix ratio was strictly prepared according to the mix parameters shown in Table 2. The cementitious material system was optimized with composite mineral admixtures, and the coarse aggregate particle size was controlled within the continuous gradation range of 5-20 mm.

[0069] Table 1 Parameters of pre-empty concrete-filled steel tubes

[0070] Steel pipe outer diameter D (mm) Steel pipe wall thickness b (mm) Steel pipe inner diameter r (mm) Ultrasonic velocity of steel pipe vs (m / s) 273 7 129.5 5800

[0071] Table 2 Mix ratio of C70 concrete in pipes

[0072] Water-cement ratio Cement (kg / m3) Silica fume (kg / m3) Sand (kg / m3) Big stone (kg / m3) Small stones (kg / m3) Expansion agent (kg / m3) Water (kg / m3) Fly ash (kg / m3) Water reducing agent (%) 0.25 360 12 804 874 219 38 119 61 1.1

[0073] According to the theoretical setting of the embodiment of the present invention, under the construction process conditions that meet the control index of concrete rheological properties (slump ≥ 220mm, expansion ≥ 550mm), the horizontal section 1-1 of the steel tube concrete structure along the radial direction (the measurement points are arranged as follows Figure 8 The ultrasonic wave velocity of the concrete in the pipe is calculated to be 5326 m / s.

[0074] Table 3 Measured ultrasonic velocity data (m / s)

[0075] First column Second column Column 3 Fourth column Fifth column Column 6 Column 7 Column 8 First row 5250 5291 5093 4643 4174 4964 5132 5210 Second row 5374 5291 5210 4964 4375 5074 5230 5438 Third row 5353 5353 5353 4581 4347 5190 5332 5353 Fourth row 5417 5395 5438 5250 4347 5270 5332 5395 Fifth row 5353 5332 5374 4535 4279 5311 5291 5332

[0076] The measured value of ultrasonic velocity vc of concrete in the pipe and the velocity characteristic parameters of the preset void height extreme position (fifth position) are inverted and analyzed by the void height dynamic calculation formula (i.e., formulas (5) and (6) in Example 2), and the quantitative detection values ​​of the void defect height H at each position are obtained as 41.8 mm, 23.0 mm, 25.6 mm, 25.6 mm, and 29.8 mm, respectively.

[0077] The test results show that the inversion results of all measuring points are within the control threshold range of ±12mm of the preset void reference value of 30mm, and the range is controlled within 18.8mm, achieving the quantitative inversion accuracy index of void defects required by the patent embodiment (relative error ≤±8%).

[0078] According to the technical specifications of the embodiment of the present invention, the original ultrasonic velocity data set recorded in Table 3 was imported into the density visualization software. After preprocessing with the thin plate spline spatial interpolation algorithm, the color partitioning rendering technology was used to generate a two-dimensional distribution map of internal defects in steel tube concrete with a resolution of ≥1ppi. The software supports two-dimensional image representation of the height of the void layer in any cross section. After coordinate registration verification, the spatial mapping error between all images and the original detection data is ≤0.5mm, meeting the concrete defect visualization reconstruction accuracy standard specified in the embodiment of the invention patent (relative error ≤±1.5%). Figure 5 shown.

Claims

1. A method for ultrasonic nondestructive testing of the density of concrete in a steel pipe, characterized in that: The following steps are involved: (1) Carry out ultrasonic measurement grid calibration in the preset area on the outer wall surface of the steel pipe to be tested, and position and install the adjustable modular soft magnetic strip array auxiliary device to achieve precise positioning of the planar transducer array; (2) Start the ultrasonic detector, use the quick-release rotating bayonet connector to achieve mechanical locking and electrical conduction between the planar transducer and the signal line, and connect the output end of the signal line to the high-frequency signal channel interface of the detector. Then align the two ends of the planar transducer to start zero-sound calibration and save the calibration results; (3) Enter the parameter setting interface and set the project parameters, including but not limited to the project name, component name, distance setting, and the number of rows and columns of measuring points in the measuring area. Use coupling agent to tightly couple the planar transducer to the first measuring point position in the measuring area on both sides of the steel tube concrete component; perform the sampling operation, and adjust it automatically or manually to ensure that the initial waveform of the first measuring point is clearly displayed on the instrument display, and then trigger the save function key to store the data of the measuring point; then, synchronously migrate the planar transducers on both sides to the next adjacent measuring point, and use coupling agent again to ensure good coupling, perform a new round of sampling, make necessary adjustments to the acquired waveform, and trigger the save function key again to record the data after the waveform meets the preset standard; repeat this process until all preset measuring points in the measuring area are tested; (4) After the test is completed, insert the USB flash drive or removable storage device into the USB port of the ultrasonic detector to export the acquired ultrasonic test data; then connect the USB flash drive or removable storage device to the computer and start the density visualization software; in the density visualization software, load the exported ultrasonic data file and use the integrated spatial coding imaging algorithm to comprehensively analyze and process the ultrasonic data; finally, generate a two-dimensional visualization image for characterizing the density of concrete in the steel pipe and a clear representation image of the void height.

2. The ultrasonic nondestructive testing method for density of concrete in steel pipe according to claim 1, characterized in that: The auxiliary device adopts a modular assembly design of strong soft magnetic strips of heterosexual rubber or a lightweight steel plate design with the same curvature as the steel pipe. The soft magnetic strips have double-sided magnetic properties and can be flexibly assembled according to the diameters of different steel pipes. Through the preset sequential excitation point layout and combined with magnetic fixation technology, precise control of the spacing between multiple measuring points can be achieved.

3. The ultrasonic nondestructive testing method for density of concrete in steel pipe according to claim 1, characterized in that: The density visualization software integrates a spatial coding imaging algorithm, analyzes and processes the measured data through thin plate spline interpolation and color partition rendering technology, and outputs a two-dimensional density distribution map and void height representation image with a resolution of ≥1ppi. It can intuitively display the defect boundary, density and void height, and supports dynamic calculation of void height. The dynamic calculation of the clearance height is based on the following formula: ， Where, is the overall ultrasonic velocity of concrete-filled steel tube, m / s; are the ultrasonic velocities of concrete and steel pipe in pipe, m / s; is the outer diameter of the concrete-filled steel tube, mm; When the first wave sound ; b is the wall thickness of the steel pipe, mm; is the inner radius of the steel pipe, mm; is the clearance height, mm.

4. The ultrasonic nondestructive testing device for density of concrete in steel pipe according to claim 1, characterized in that: The ultrasonic detection machine is suitable for detection in the sound speed range of 1000m / s to 8000m / s. Through the directional transmission and reception of high-frequency electrical signals, it significantly improves the propagation stability and data reliability of ultrasonic waves in complex high-altitude environments. It analyzes parameters in real time, such as the first wave sound time, amplitude attenuation and waveform distortion, to achieve low-error quantitative calculation of the airborne height, so that the error between the detection value and the actual value is maintained at ±12mm.

5. A device for the ultrasonic nondestructive testing method for density of concrete in a steel pipe according to any one of claims 1 to 4, characterized in that: include: An ultrasonic testing machine, comprising an ultrasonic detector, a planar transducer, and a signal line, wherein the signal line is connected to the planar transducer interface on the ultrasonic detector, and the planar transducer and the signal line are detachably connected via a matching quick-release rotating bayonet connector; Auxiliary devices, using modular assembly design of strong soft magnetic strips of heterogeneous rubber or lightweight steel plates with the same curvature as the steel pipe, are used to achieve precise positioning of the transducer array; The density visualization software integrates a spatially coded imaging algorithm to analyze and process ultrasonic testing data and generate a two-dimensional density distribution map and void height representation image.

6. The device according to claim 5, characterized in that The dimensions of the auxiliary device are 480 mm in length and 340 mm in width, with a distance of 25 mm between the two measuring points and a total weight of ≤2 kg. It can quickly adapt to steel pipes of different diameters from 0.3 m to 3 m, and the installation time is shortened to within 10 minutes.

7. The device according to claim 5, characterized in that The density visualization software converts the serial ultrasonic excitation data into a two-dimensional distribution map of the density of steel tube concrete through thin plate spline interpolation and color partition rendering technology. The blue to red gradient represents the density of 0-100%, and the area, boundary and defect density of the void area are intuitively displayed. The resolution of the two-dimensional surface defect image inside the steel tube concrete is ≥1ppi.

Images