Concrete crack three-dimensional shape recognition device and method based on ultrasonic waves

Abstract

The invention discloses a concrete crack three-dimensional shape recognition device and method based on ultrasonic waves, the shape recognition device comprises an injection device and a sealing device, the injection device comprises a liquid storage cavity, a volume detection module, a pressurization module, a crack width measurement module, a focusing probe transducer, an imaging module and a display screen; the three-dimensional crack identification method comprises the following steps: sealing a crack; debugging the injection device, and connecting the sealing device with the injection device; injecting a tracer agent into the crack; setting a coordinate origin and a reference system; moving the injection device along a reference system, transmitting the calculated crack boundary depth and the plane coordinates of the measurement points obtained by the positioning device to an imaging module, and generating a crack two-dimensional form in the cross section of the crack through a quadratic spline interpolation method; and the collected ultrasonic signals are stored in an imaging module, and the precision of the established three-dimensional crack form model is judged. According to the invention, the problems of high cost and insufficient precision of existing concrete surface crack detection and three-dimensional crack model establishment are solved.

Description

Technical Field

[0001] This invention relates to the field of non-destructive testing equipment for cracks, and more particularly to a device and method for three-dimensional morphological recognition of concrete cracks based on ultrasound. Background Technology

[0002] Cracks reflect the structural stress state and its safety and durability. Structures may crack under loads, temperature effects, fatigue, uneven foundation settlement, earthquakes, and other forces, and these cracks threaten structural safety. In particular, cracking in concrete structures can cause the protective layer to fail in protecting the internal reinforcing steel, leading to steel corrosion and expansion, inducing more cracks, and thus reducing structural durability. Therefore, cracks are a manifestation of structural damage, an early warning of insufficient durability, and a precursor to structural failure. Concrete is currently the most widely used building material. To ensure the safety and function of building structures, extensive and accurate structural health testing of concrete surfaces is necessary to maintain the stable operation of such infrastructure.

[0003] Existing methods for detecting concrete surface cracks and establishing 3D crack models include 3D laser scanning and CT slicing. While 3D laser scanning can obtain a 3D model of the crack, the cracks on the concrete surface are often very fine, and the concrete sidewalls within the crack may be uneven. Therefore, the 3D crack model obtained using 3D laser scanning may not accurately reflect the actual crack. CT slicing can accurately obtain a 3D model of the crack, but it damages the concrete surface and is costly, making it unsuitable for engineering inspection.

[0004] Ultrasonic-based non-destructive testing methods for concrete cracks can detect crack depth, but the signal changes are not obvious due to insufficient scattered energy in concrete, ultimately leading to insufficient measurement accuracy. This method, combined with a tracer, can more accurately establish a three-dimensional model of concrete surface cracks; however, the injection pressure of the tracer and the sealing properties of the crack will affect the distribution of the tracer and the accuracy of establishing the three-dimensional crack model.

[0005] In summary, the methods for detecting cracks on concrete surfaces and establishing three-dimensional cracks still suffer from high costs and insufficient accuracy. Improving detection accuracy while reducing costs is a technical problem that urgently needs to be solved. Summary of the Invention

[0006] Purpose of the invention: The purpose of this invention is to overcome the shortcomings of the prior art and propose a three-dimensional morphological recognition device and method for concrete cracks based on ultrasound. It integrates a tracer injection device, a crack sealing device, an ultrasonic flaw detection device, and a crack imaging module, and integrates the control of injection pressure, accurate measurement of injection volume, and real-time and accurate establishment of a three-dimensional crack morphological recognition model, thereby solving the problems of high cost and insufficient accuracy in existing concrete surface crack detection and three-dimensional crack model establishment.

[0007] Technical solution: The present invention provides a three-dimensional morphological identification device for concrete cracks based on ultrasound, comprising an injection device and a sealing device; an infusion tube for inputting tracer is located between the sealing device and the injection device.

[0008] The injection device includes a reservoir, a volume detection module, a pressurization module, a crack width measurement module, a focusing probe transducer, an imaging module, and a display screen; the reservoir has a cap, an injection port, and an outlet; the volume detection module measures the output volume of the tracer; the pressurization module pressurizes the tracer; the crack width measurement module has a built-in microscopic device, a measuring device, and a positioning device.

[0009] The injection device is equipped with a storage device for securing the infusion tubing.

[0010] This invention relates to a method for identifying the three-dimensional morphology of concrete cracks based on ultrasound. The method is implemented by an ultrasound-based three-dimensional morphology identification device for concrete cracks and includes the following steps:

[0011] Step 1): Determine the fixing position of the sealing device according to the distribution of cracks on the concrete surface, initially seal the cracks, and use a sealing strip to further seal the remaining cracks.

[0012] Step 2): Adjust the injection device and connect the sealing device to the injection device through the infusion tube.

[0013] Step 3): Inject the ultrasonic tracer into the injection device through the injection port, seal the injection port with the cap, and fill the injection device and sealing device with tracer; zero the volume detection module so that the initial reading of the volume detection module is 0; set the pressure of the pressurization module and apply constant pressure to the tracer; open the infusion port at the bottom of the sealing plate to allow the tracer to fill the crack; after the tracer fills the crack, record the volume measured by the volume detection module, disconnect the infusion tube from the sealing device, and store it in the infusion tube storage area on the surface of the box.

[0014] Step 4): Set the coordinate origin and reference system using the positioning device in the crack width measurement module. The reference line is on one side of the crack and parallel to the crack. The equidistant measurement line is perpendicular to the reference line and passes through the crack. The seamless measurement line is parallel to the equidistant measurement line but does not pass through the crack. The coordinate origin is located on one side of the crack and at a certain distance from the crack. A reference line parallel to the crack is taken through the coordinate origin. An equidistant measurement line perpendicular to the reference line and passing through the crack and a seamless measurement line that does not pass through the crack on the concrete surface are taken. The spacing between the equidistant measurement lines is Δy. The seamless measurement line is used to measure and correct the actual propagation speed of ultrasonic waves in concrete.

[0015] Step 5): Based on the established reference frame, move the injection device along the equidistant measurement line, observe the cracks on the concrete surface on the display screen and read their widths. Taking the crack boundary on the equidistant measurement line as the starting point, take measurement points with an equal interval of Δw. At each measurement point, activate the high-frequency narrow-beam focusing probe transducer to acquire the ultrasonic signal at each measurement point, i.e., the time history diagram of the reflected wave signal intensity, and calculate the crack boundary depth h at each measurement point.

[0016] Among them, v i Let t be the speed at which ultrasound propagates in the i-th medium. i Let be the propagation time of the ultrasonic wave in the i-th medium;

[0017] The planar coordinates of each measurement point obtained by the positioning device in the crack boundary depth and crack width measurement module are transmitted to the imaging module in real time, and the two-dimensional morphology of the crack in the crack cross section is generated by the quadratic spline interpolation method.

[0018] Step 6): In the imaging module, the two-dimensional crack morphology within the cross-section of each crack is stitched together using a quadrilateral mesh method to form a three-dimensional model of the concrete crack morphology. The three-dimensional model of the crack morphology is transmitted and displayed on the screen. Simultaneously, the volume of the three-dimensional model of the crack morphology is calculated and compared in the imaging module with the volume of tracer injection to determine the accuracy of the three-dimensional model of the crack morphology, thereby monitoring the distribution of concrete cracks.

[0019] use To determine the accuracy of the three-dimensional crack morphology model, if E≤10%, the accuracy of the constructed three-dimensional crack morphology model meets the requirements.

[0020] Where E is the volume error of the three-dimensional model of the crack morphology, and V m V is the volume of the 3D model. s This refers to the volume of tracer injected.

[0021] In step 4), the positioning device in the crack width measurement module marks the coordinate origin and acquires the planar coordinates of the device relative to the origin, i.e., the x and y coordinates, in real time during the movement of the device, and displays them synchronously on the display screen; wherein, the planar coordinates on the display screen are used to determine whether the injection device is located on the equidistant measurement line.

[0022] In step 5), the crack width measurement module has a built-in measuring device that reads and displays the crack width on the screen, while the measurer corrects the width data and stores it in the imaging module.

[0023] In step 5), the calculation process for the ultrasonic signal and crack depth is as follows:

[0024] like Figure 9 , Figure 10As shown, when the focused probe transducer is activated at the measurement point, the emitted ultrasonic waves will be reflected back to the focused probe transducer when they encounter the crack boundary. The depth at each point is calculated by the propagation time of the ultrasonic waves at each point. Figure 9 As shown in (b), when the focused probe transducer measures a simple crack, the emitted ultrasonic wave, after passing through glycerol and contacting the crack boundary, is directly reflected back to the focused probe transducer via the glycerol. That is, the ultrasonic wave travels from C to D and back to C, and the signal can be transmitted back to the focused probe transducer. Figure 9 (a) shows the propagation time t of the ultrasound throughout the process. Let v be the speed of ultrasound propagation in glycerol. l Then the depth of the corresponding point is h = v l t / 2; Similarly, the principle for calculating the deepest point depth of a simple crack is as follows: Figure 9 As shown in (c), the ultrasonic wave travels from E to F and back to E, so the depth of the deepest point is h = v. l t / 2; as Figure 10 As shown in (b), when the ultrasonic waves emitted by the focused probe transducer need to pass through multiple crack interfaces (two are used as an example below), the ultrasonic waves first travel through the concrete to the crack boundary. Part of the ultrasonic signal is reflected back to the focused probe transducer; that is, the ultrasonic waves travel from G to H and back to G. The remaining ultrasonic signals continue to travel downwards through the concrete, are emitted when they pass the crack boundary, and are finally received by the focused probe transducer. In other words, after the ultrasonic waves travel from G to H, they continue from H to I, then from I to H, and finally from H to G. (In signal...) Figure 10 (a) The propagation time of the ultrasonic waves in the two processes described above is displayed. Let the propagation time of the first process be t1, and the propagation time of the second process be (t1+t2). The true propagation speed of the ultrasonic waves in the measured concrete after measurement correction is v. c Then the depth of the first crack boundary is h1 = v c t1 / 2, the depth of the second crack boundary is h2=(v c t1+v l t2) / 2; Similarly, the calculation of the deepest point depth of complex cracks is as follows: Figure 9 As shown in (c), the ultrasonic wave is transmitted from J to K and then back to J, and the depth of the deepest point is h = v. c t1 / 2; therefore, the formula for calculating the boundary depth of each crack is:

[0025]

[0026] Where h is the crack boundary depth, v i Let t be the speed at which ultrasound propagates in the i-th medium. i Let be the propagation time of the ultrasonic wave in the i-th medium.

[0027] In step 5), the sampling window, number of stacks and sampling rate are continuously adjusted, and the detection is repeated no less than 3 times on each detection line. Step 52: After obtaining the two-dimensional shape of a certain crack cross section, the liquid injection device is moved to the equidistant measurement line Δy to continue measuring the two-dimensional shape of the next crack cross section.

[0028] In step 5), the imaging module stores the preprocessed ultrasonic signals and planar coordinates in the buffer to the solid-state drive; it analyzes the ultrasonic signals of the cross-section of the crack where each measurement line is located, and obtains the crack morphology of each cross-section of the crack through quadratic spline interpolation.

[0029] In step 5), the process of generating the two-dimensional crack morphology within the crack cross section using quadratic spline interpolation is as follows:

[0030] The planar coordinates and depths of the measurement points within the crack cross-section are transformed into three-dimensional coordinates (x, y, z). Since the y-coordinates of measurement points on the same measurement line are the same, quadratic spline interpolation is performed using the x and z coordinates. That is, given n data points (x1, z1), ..., (x...) on the same measurement line... n ,z n ), in the interval [x i ,x i+1 Construct a quadratic spline polynomial S in [the context of the original text]. i (x),

[0031] S i (x)=a i +b i (xx i )+c i (xx i ) 2 (2)

[0032] Interpolation conditions are met:

[0033] S i (x i )=z i (3)

[0034] S i (x i+1 )=z i+1 (4)

[0035] Let the quadratic spline polynomial function S i (x) If we maintain continuity, the first derivative remains continuous, and the crack boundary is a natural boundary, then

[0036]

[0037] Where S i (x) represents the interval [x] i ,x i+1The quadratic spline polynomial constructed in ], a i b i c i x is the coefficient. i z i Let S be the x-coordinate and depth of the crack boundary at the i-th measurement point out of n measurement points within the crack cross-section. i (x i+1 ) is the interval [x i ,x i+1 The quadratic spline polynomial constructed in ] is in x = x i+1 The value at point S i+1 (x i+1 ) is the interval [x i+1 ,x i+2 The quadratic spline polynomial constructed in ] at the point x = x i+1 The value at point S i '(x i+1 ) is the interval [x i ,x i+1 The quadratic spline polynomial constructed in ] is in x = x i+1 The first derivative value at point S i+1 ′(x i+1 ) is the interval [x i+1 ,x i+2 The quadratic spline polynomial constructed in x = x i+1 S1″(x1) is the first derivative value at x = x1, and S2″(x1) is the second derivative value of the quadratic spline polynomial constructed in the interval [x1,x2] at x = x1. n-1 "(x n ) is the interval [x n-1 ,x n The quadratic spline polynomial constructed in x = x n The value of the second derivative at that point.

[0038] The quadratic spline polynomials for each interval are obtained through calculation, namely, the intervals [x1, x2], [x2, x3], ..., [x...]. n-1 ,x n The quadratic spline polynomial over [ ]. Due to different interval properties, the methods for finding quadratic spline polynomials fall into two categories: boundary intervals and intermediate intervals. Boundary intervals can be directly obtained through boundary conditions, while intermediate intervals cannot be directly obtained through boundary conditions. They can only be obtained by using the first boundary interval polynomial, S1(x), which has already been obtained through boundary conditions, as the initial value, and then by applying the derivative continuity condition, S... i ′(x i+1 ) = S i+1 '(x i+1 Solve recursively. Specifically, for the boundary intervals [x1, x2], [x... n-1 ,x nFrom equations (3), (4) and (5), S1″(x1)=S n-1 "(x n The quadratic spline polynomial is obtained by finding that ) = 0. For example, if the data points (x1, z1) and (x2, z2) on the interval [x1, x2] are known, then from equation (3) we get a1 = z1. From the boundary condition S1″(x1) = 0 in equation (5), we can get c1 = 0. And from equation (4) we get The quadratic spline polynomial on the boundary interval [x1, x2] is finally determined as follows: For the intermediate intervals [x2,x3], [x3,x4], ..., [x...] n-2 ,x n-1 From equations (3), (4) and (5), S i '(x i+1 ) = S i+1 '(x i+1 The quadratic spline polynomial is obtained. For example, if the data points (x2, z2) and (x3, z3) on the interval [x2, x3] are known, then from equation (3) we get a2 = z2, and from equation (4) we get a2 + b2(x3 - x2) + c2(x3 - x2). 2 =z3, and from the derivative continuity condition S in equation (5) i '(x i+1 ) = S i+1 ′(x i+1 We get b1 + 2c1(x2 - x1) = b2 + 2c2(x2 - x1). From the above process of solving the boundary interval, we know that the previous interval S1(x) has been obtained. Therefore, we get...

[0039] In the above results b2 and c2, b1 and c1 are the coefficients of the obtained quadratic spline polynomial S1(x). Using b1 and c1 simplifies the results b2 and c2. Substituting the results b2 and c2 into the expression for the quadratic spline polynomial S2(x), the quadratic spline polynomial on the intermediate interval [x2, x3] is finally determined as follows:

[0040]

[0041] The resulting quadratic spline polynomial is the connecting line between adjacent measurement points within the same crack profile, which is the connecting line between adjacent boundary points of the crack within the crack profile. By connecting each boundary point according to the quadratic spline polynomial, the crack boundary of the crack cross section is formed, thereby determining the two-dimensional morphology of the crack.

[0042] In step 6), the process of stitching together the two-dimensional crack morphologies within the cross-section of each crack using the quadrilateral mesh method in the imaging module is as follows:

[0043] Given that there are Y cross-sections of cracks, the coordinates of the boundary points (measurement points) in each cross-section are... Where l is the cross-sectional number of the crack, and m l Let be the number of boundary coordinate points on the l-th crack cross-section. To ensure that the cross-sections of each crack correspond and are stitched together, the same number of corresponding points are taken for the boundaries of each cross-section. At the same time, to ensure the authenticity of the crack cross-sections, it is necessary to retain the information at the deepest point of each crack cross-section. Therefore, the boundaries of each crack cross-section are first resampled, and the deepest point of each crack cross-section is taken as the starting point for resampling.

[0044] like Figure 11 As shown in (a), the cumulative arc length s is calculated for the deepest point of each crack cross section. k :

[0045] make

[0046] Construct the arc length parameter t at the k-th point k ,make

[0047] Where s1 is the cumulative arc length of the deepest point in the crack cross section, s k Let t be the cumulative arc length at the k-th point. k Let be the arc length parameter for the k-th point.

[0048] To obtain the x and z coordinates of each corresponding point after resampling, the quadratic spline interpolation method in step 5) is used to construct the coordinates x and z and the arc length parameter t. k The function;

[0049] That is, by

[0050] We get x = F(t), and similarly we get z = G(t).

[0051] Take N equally spaced points on the interval t∈[0,1] to obtain the coordinates of the boundary points of the resampled cross-section. in x j =F(t) j ), z j =G(t) j ), j is the boundary point number of the resampled cross-section, l is the cross-section number of the crack, t j Let x be the parameter coordinates of the j-th point after resampling. j , z j These are the coordinates of the j-th point after resampling.

[0052] like Figure 11 As shown in (b), the j-th point on the cross-section of crack l is denoted as... Its coordinates are Corresponding points of adjacent cross sections and Connect the points by quadrilaterals. and Connect them, l∈[1,Y-1]j∈[1,N-1], and splice them to form a three-dimensional crack morphology model.

[0053] In step 6), the accuracy of the crack 3D morphology model is determined using the following formula:

[0054]

[0055] Where E is the volume error of the three-dimensional model of the crack morphology, and V m V represents the volume of the three-dimensional morphological model, calculated by the imaging device using a parallelized hardware algorithm based on voxel accumulation. s The tracer injection volume is measured by the volume detection module in the injection device. When E ≤ 10%, the constructed three-dimensional crack morphology model meets the accuracy requirements; when E > 10%, the constructed three-dimensional crack morphology model does not meet the requirements. By reducing the measurement point spacing Δw in step 5) and the measurement line spacing Δy in step 4), the width, depth, and orientation of the crack are re-acquired, and the three-dimensional crack morphology model is established until the volume of the three-dimensional morphology model is within the error range.

[0056] In step 4), the distance between the equidistant measurement lines is 2-3 cm.

[0057] In step 4), the distance between the reference line and the crack is 10-30 cm.

[0058] In step 3), the ultrasonic tracer is glycerol with a purity ≥95%. This glycerol contains 0.5-2% by weight of nano-sized alumina powder as a scattering enhancer.

[0059] The initial value of the measurement point interval Δw is set to 0.05mm, and then adjusted according to the accuracy of the obtained three-dimensional model.

[0060] In step 4), the length of the reference line is greater than the length of the crack to be tested.

[0061] In step 3), the pressure applied by the pressurizing module is in the range of 0.2-0.5 MPa.

[0062] In step 4), each crack to be tested has at least 5 equidistant measurement lines, and the initial value of the spacing Δy between the equidistant measurement lines is adjusted appropriately according to the accuracy of the obtained three-dimensional model.

[0063] In step 5), after obtaining the two-dimensional morphology of a certain crack cross section, the injection device is moved to the measurement line Δy at a distance to continue measuring the two-dimensional morphology of the next crack cross section, i.e., as shown below. Figure 7 After obtaining the crack cross section AB, the crack cross section LM is measured.

[0064] Beneficial effects: Compared with the prior art, the present invention has the following advantages:

[0065] (1) The present invention is a method for identifying three-dimensional morphology of concrete cracks based on ultrasound. It integrates a tracer injection device, a crack sealing device, an ultrasonic flaw detection device, and a crack imaging module. It integrates the control of injection pressure, accurate measurement of injection volume, and instantaneous and accurate establishment of a three-dimensional morphology identification model of cracks. While reducing measurement costs, it improves the efficiency of three-dimensional morphology identification of cracks.

[0066] (2) This invention uses high-precision, high-resolution ultrasound as a carrier and glycerol as an ultrasound tracer to detect and establish a three-dimensional morphological model of cracks, thereby reducing costs and further improving the accuracy of non-destructive testing of cracks. Attached Figure Description

[0067] Figure 1 This is a schematic diagram of the steps of the ultrasonic-based three-dimensional morphology recognition method for concrete cracks according to the present invention.

[0068] Figure 2 This is a schematic diagram of the overall structure of the liquid injection device of the present invention;

[0069] Figure 3 This is a cross-sectional view of the injection device of the present invention along the centerline;

[0070] Figure 4 This is a bottom view of the sealing device of the present invention;

[0071] Figure 5 This is a cross-sectional view of the sealing device of the present invention;

[0072] Figure 6 This is a diagram of the liquid crystal display screen interface of the present invention;

[0073] Figure 7 This is a schematic diagram of the reference frame distribution of the present invention;

[0074] Figure 8 This is a schematic diagram of crack width measurement according to the present invention;

[0075] Figure 9 This is a schematic diagram of a simple crack depth measurement method according to the present invention.

[0076] Figure 10 This is a schematic diagram illustrating the measurement of complex crack depth according to the present invention;

[0077] Figure 11 This is a schematic diagram of the cross-sectional splicing of the crack in this invention. Detailed Implementation

[0078] Figures 1 to 11In the middle section: 1-Injection port; 2-Cap; 3-Storage chamber; 4-Outlet; 5-Volume detection module; 6-Infusion tube storage area; 7-Pressure module; 8-Crack width measurement module; 9-High-frequency narrow beam focusing probe transducer; 10-Imaging module; 11-LCD display screen; 12-Infusion tube; 13-Sealing plate; 14-Sealing strip; 15-Infusion port; 16-Sensor; 17-Reference line; 18-Measurement line; 19-Crack.

[0079] This embodiment takes the detection and three-dimensional modeling of floor slab cracks in a building project as an example to illustrate the specific implementation process of the ultrasonic-based three-dimensional morphology recognition device and method for concrete cracks of the present invention.

[0080] The ultrasonic-based three-dimensional morphology recognition device for concrete cracks used in this embodiment includes an injection device and a sealing device. The sealing device is connected to the injection device via an infusion tube.

[0081] The injection device includes an injection port 1, located on the upper surface of the injection device housing, for injecting the tracer; a cap 2, for sealing the injection port; a storage chamber 3, connecting the injection port and the outlet, for storing and transporting the radar tracer; an outlet 4, located in the center of the side surface of the injection device housing, for outputting the tracer; a volume detection module 5, located above the outlet, for measuring the output volume of the tracer; a tubing storage area 6, located on the side surface of the housing, for storing the tubing; a pressurization module 7, located on the side of the storage chamber, for applying constant pressure to the tracer according to a set pressure; and a crack width measurement module 8, located opposite the outlet of the housing, which includes a built-in microscope, measuring device, and positioning device. This module can magnify the crack morphology on the concrete surface and read the crack width through a built-in scale, while also acquiring real-time relative information about the housing. The system includes: a plane coordinate system at the set origin; a high-frequency narrow-beam focusing probe transducer 9, located above the crack width measurement module, which can transmit and receive ultrasonic signals through holes at the bottom of the housing; an imaging module 10, located above the high-frequency narrow-beam focusing probe transducer 9, used to store and analyze ultrasonic information and synchronously process the plane coordinates from the crack width measurement module positioning device to construct a three-dimensional crack morphology model; an LCD screen 11, located on the upper surface of the housing, which can display the injection volume, injection pressure, crack surface morphology magnified by the crack width measurement module, crack width, two-dimensional morphology of the crack cross section, plane coordinates of the housing relative to the set origin, three-dimensional crack morphology model, and three-dimensional model volume error; and an infusion tube 12, used to deliver radar tracer and connect the injection device and sealing device.

[0082] The sealing device includes a sealing plate 13 for fixing the tracer injection position and initially sealing the crack; a sealing strip 14, which is bonded to the sealing plate and can seal the crack outside the sealing plate; an infusion port 15, located in the center of the sealing plate, for delivering the tracer; and a sensor 16, located at the bottom of the sealing plate, close to the infusion port, which can transmit information to the pressurization module and is responsible for detecting whether the tracer has overflowed. If the crack is detected to be full, that is, when the tracer overflows, a signal is immediately transmitted to the pressurization module to stop pressurization.

[0083] More preferably, in this embodiment, the injection device adopts a cuboid box made of high-strength ABS engineering plastic, with external dimensions of 450mm×320mm×280mm, and an internal 6L volume liquid storage chamber that can withstand pressures up to 1.0MPa. The pressurization module uses a miniature electric diaphragm pump (model DP-60), with a pressure adjustment range of 0.1-0.8MPa and a pressure control accuracy of ±0.005MPa; the volume detection module uses an electromagnetic flowmeter (model DF-20), with a range of 0-15L / min and a measurement accuracy of ±0.3%; the crack width measurement module uses a high-precision concrete crack width gauge (model HC-CK102), with a built-in microscope (magnification of 10-40x) for clear observation of concrete surface crack morphology. Below the lens is an integrated electronic scale measurement system (accuracy up to 0.01mm), which can automatically identify crack edges and directly read width values ​​through image processing technology. It also incorporates a laser positioning module and a plane coordinate sensor (infrared positioning technology). The instrument can record the x and y plane coordinates of the instrument relative to the preset origin in real time and transmit them synchronously to the subsequent processing module. The high-frequency narrow beam focusing probe transducer adopts an 8MHz high-frequency piezoelectric ceramic transducer with a transmission power of 800W and a beam angle of ≤10°, and has dual functions of transmission and reception. The imaging module is equipped with a dual-core processor (2.5GHz), 8GB of memory and 128GB of solid-state drive, including a data acquisition card and dedicated algorithm software. It is responsible for storing and analyzing ultrasonic propagation time and amplitude information, and at the same time receiving the plane coordinate data transmitted by the crack width measurement module. Through the three-dimensional reconstruction algorithm, it constructs a three-dimensional morphological model of the crack, including its depth, direction and branches. Together with the high-frequency narrow beam focusing probe transducer, it forms an ultrasonic crack three-dimensional imaging system.

[0084] More preferably, the sealing plate of the sealing device is made of aviation aluminum alloy, with a diameter of 200mm and a thickness of 12mm; the sealing strip bonded to it is made of EPDM rubber, with a cross-sectional size of 12mm×12mm and a Shore hardness of 65±5; the infusion port is located in the center of the sealing plate, with a diameter of 12mm; the sensor is a non-contact ultrasonic liquid level sensor (model US-300), with a response time of less than 8ms. When the tracer liquid level is detected to reach the threshold, a stop signal is immediately sent to the pressurization module.

[0085] In this embodiment, the sealing strip is made of elastic rubber. The volume detection module uses a high-precision flow meter to measure the output volume of the tracer in real time and accurately. The pressurization module uses an electric pressurization pump to precisely control the pressure.

[0086] The present invention provides a method for three-dimensional morphological identification of concrete cracks based on ultrasound, comprising the following steps:

[0087] Step 1: First, use high-pressure water to wash the surface of the concrete crack to remove oil, dust and loose particles; then, attach a 60mm wide EPDM rubber sealing strip along the crack direction; finally, fix the sealing plate at the center of the crack with expansion bolts, ensuring that the inlet is precisely aligned with the center of the crack and that the sealing plate adheres to the concrete surface with a degree greater than 95%.

[0088] Step 2: Take out a 2m long, 10mm inner diameter high-pressure polyurethane infusion tube, connect one end to the outlet of the injection device, insert the other end into the infusion port of the sealing plate and tighten it; turn on the injection device, use the standard scale plate on the LCD screen to verify and calibrate the crack width measurement module to ensure accurate recognition of the 0.01mm scale; calibrate the zero point of the electromagnetic flowmeter; test the transmission and reception functions of the high-frequency narrow beam probe transducer, and observe whether a clear initial ultrasonic signal appears on the display screen.

[0089] Step 3: Prepare the ultrasonic tracer by adding 1.2% by weight of nano-alumina powder with an average particle size of 80nm to 98% pure glycerol. Inject 300mL of the prepared tracer into the reservoir through the injection port. Open the infusion valve and manually squeeze the reservoir to expel air from the tube until the tracer overflows from the infusion port, confirming that the tubing is full. Reset the volume detection module reading to 0, set the pressure of the pressurization module to 0.35MPa, and open the infusion valve. After 5 minutes, the sensor at the bottom of the sealing plate detects the tracer overflow, and the pressurization module automatically stops working. At this time, the volume detection module displays an injection volume of 48.6mL. Record this value, disconnect the infusion tube, and store it in the infusion tube storage area on the side surface of the box.

[0090] Step 4: Mark the coordinate origin 100cm away from one side of the crack using the crack width measurement module positioning device. Take a reference line roughly parallel to the crack, passing through the coordinate origin. The reference line should be 100cm long, longer than the crack length. Then, take equidistant measurement lines perpendicular to the reference line.

[0091] The origin (0,0) is chosen as the coordinate origin. A straight line perpendicular to the reference line is drawn through the origin as the first measurement line (y=0). Equidistant measurement lines are set along the reference line, with a spacing Δy=10mm, for a total of 8 measurement lines covering the entire length of the crack, numbered from y=0 to y=70mm. An additional seamless measurement line is set 10cm from the end of the crack in the crack-free area to calibrate the propagation speed of ultrasonic waves in concrete. The measured velocity v... c =3200m / s.

[0092] Step 5: Move the injection device along the first measurement line (y=0), magnify the image of the crack through the crack width measurement module, read the surface width as 0.32mm, manually correct the error and store it; take 67 measurement points at intervals of Δw=0.05mm, with the crack boundary A (x=2.5mm) as the starting point and the boundary B (x=5.8mm) as the ending point;

[0093] At each measurement point, a high-frequency narrow-beam probe is activated to acquire ultrasonic reflection signals (as shown in the attached image). Figure 9 (a), 10(a)), each measurement line is repeatedly probed 3 times, the average signal value is taken, and the depth is calculated in the imaging module according to the following formula (1):

[0094]

[0095] Where h is the crack boundary depth, v i Let t be the speed at which ultrasound propagates in the i-th medium. i Let be the propagation time of the ultrasonic wave in the i-th medium;

[0096] For example, the ultrasonic signal at the 10th measurement point (x = 3.0 mm, y = 0) shows a propagation time of t = 12 μs. According to the formula h = v l ×t / 2(v l =1920m / s is the speed of sound in glycerol), and the calculated depth h = 11.52mm; for measurement points with complex shapes (such as those with two crack interfaces), based on the signal diagram t1 = 8μs (propagation in concrete) and t2 = 5μs (propagation in glycerol), the depth h is calculated using the formula h = (v c ×t1+v l The depth of the second interface, h2, is calculated as (3200×8+1920×5)×10 × t2) / 2. 6 / 2=18.56mm.

[0097] As attached Figure 11 As shown in (a), the imaging module uses formulas (2)-(5) to fit the measurement points (x,y,z) on the same cross-section of the crack through quadratic spline interpolation to generate the two-dimensional crack morphology of the cross-section of the crack.

[0098] Si (x)=a i +b i (xx i )+c i (xx i ) 2 (2)

[0099] S i (x i )=z i (3)

[0100] S i (x i+1 )=z i+1 (4)

[0101]

[0102] Where S i (x) represents the interval [x] i ,x i+1 The quadratic spline polynomial constructed in ], a i b i c i x is the coefficient. i z i Let S be the x-coordinate and depth of the crack boundary at the i-th measurement point out of n measurement points within the crack cross-section. i ′(x) and S i "(x) represents the first and second derivatives of the quadratic spline polynomial.

[0103] In step 5), the crack depth measurement process is as follows: Figure 8 As shown, the crack boundary on the measurement line is determined by observing the crack morphology on the concrete surface in the LCD screen. Taking crack boundary A as the starting point and B as the ending point, measurement points are taken at intervals of Δw. At each measurement point, the focusing probe transducer is activated to collect ultrasonic signals and transmit and store them to the imaging module to calculate the depth at each measurement point. The sampling window, number of superpositions and sampling rate are continuously adjusted, and the detection is repeated no less than 3 times on each detection line.

[0104] Step 6: To ensure the cross-sectional profiles of each crack correspond and fit together, the same number of corresponding points are taken at the boundaries of each crack cross-section. Simultaneously, to guarantee the accuracy of the crack cross-sections, information at the deepest point of each crack cross-section needs to be preserved. Therefore, the boundaries of each crack cross-section are first resampled, with the deepest point of each crack cross-section serving as the starting point for resampling.

[0105] like Figure 11 As shown in (a), the cumulative arc length s is calculated for the deepest point of the crack cross section of the 8 measurement lines according to formulas (6)-(8). k The two-dimensional morphology of the cross-section of the crack is resampled:

[0106] Taking the two-dimensional morphology of a crack cross section at point AB as an example:

[0107]

[0108] Where s1 is the cumulative arc length at the deepest point of the crack cross-section, s k Let t be the cumulative arc length at the k-th point. k Let be the arc length parameter for the k-th point.

[0109]

[0110] Where F i (t) represents the interval [t] i ,t i+1 Construct a quadratic spline polynomial in x, a i b i c i t is a coefficient i x i Let F be the arc length parameter and abscissa of the crack boundary at the i-th measurement point out of n measurement points in the crack cross section. i ′(t) and F i "(x) represents the first and second derivatives of the quadratic spline polynomial.

[0111] We get x = F(t), and similarly we get z = G(t).

[0112] Take N equally spaced points in the interval t∈[0,1] to obtain the coordinates of the boundary points of the crack cross section after resampling. in x j =F(t) j ), z j =G(t) j ), j is the boundary point number of the crack cross section after resampling, l is the crack cross section number, t j Let x be the parameter coordinates of the j-th point after resampling. j , z j These are the coordinates of the j-th point after resampling.

[0113] like Figure 11 As shown in (b), let the j-th point on the cross-section of crack l be denoted as . Its coordinates are Corresponding points of adjacent crack cross sections and By splicing together using the quadrilateral grid method, that is, by connecting the points... and Connected, l∈[1,Y-1]j∈[1,N-1]. For example, point P5 on the cross section of the crack where y=0. 1(3.0,0,11.52) The corresponding point of (3.3,0,12.52) and the cross-section of the crack with y=10mm. (3.2,10,12.30) (3.2, 10, 12.30) Using quadrilaterals connect.

[0114] The imaging module generates a three-dimensional model of the crack and displays it on the LCD screen, calculates the model volume, and calculates the error according to formula (9):

[0115]

[0116] Where E is the model volume error, V m V is the volume of the 3D model. s This represents the tracer injection volume. When E ≤ 10%, the model meets the accuracy requirements; when E > 10%, the model does not meet the requirements. Crack information can be re-acquired by reducing the measurement point spacing Δw in step 5 and the measurement line spacing Δy in step 4, and a three-dimensional crack morphology model can be established until the model volume is within the error range.

[0117] Such as the volume V of the three-dimensional morphological model of the crack m = 52.3 mL, tracer volume V s =48.6mL, so E=|52.3-48.6| / 48.6×100%≈7.6%≤10%, the model meets the accuracy requirements.

[0118] Once the three-dimensional crack morphology model is established, it will intuitively display the width, depth, and direction of concrete cracks, providing data support for determining the safety of concrete structures.

Claims

1. A three-dimensional morphological recognition device for concrete cracks based on ultrasound, characterized in that: It includes an injection device and a sealing device; an infusion tube for introducing tracer is located between the sealing device and the injection device; The injection device includes a reservoir, a volume detection module, a pressurization module, a crack width measurement module, a focusing probe transducer, an imaging module, and a display screen; the reservoir has a cap, an injection port, and an outlet; the volume detection module measures the output volume of the tracer; the pressurization module pressurizes the tracer; the crack width measurement module incorporates a microscopic device, a measuring device, and a positioning device.

2. The ultrasonic-based three-dimensional morphology recognition device for concrete cracks according to claim 1, characterized in that: The injection device is equipped with a storage device for fixing the infusion tube.

3. A method for three-dimensional morphological recognition of concrete cracks based on ultrasound, characterized in that: The identification method, implemented by the ultrasonic-based three-dimensional morphology identification device for concrete cracks as described in claim 1, includes the following steps: Step 1): Use a sealing device to initially seal the concrete cracks, and use a sealing strip to seal the remaining cracks; Step 2), connect the sealing device to the injection device via the infusion tubing; Step 3) Inject the ultrasonic tracer into the injection device, seal the injection port with the cap, and fill the injection device and sealing device with ultrasonic tracer; zero the volume detection module; set the pressure of the pressurization module and apply constant pressure to the ultrasonic tracer; open the outlet to fill the crack with tracer, record the volume measured by the volume detection module, and disconnect the infusion tube from the sealing device. Step 4): Set the coordinate origin and reference system using the positioning device in the crack width measurement module, set the reference line to one side of the crack and parallel to the crack, set the equidistant measurement line to be perpendicular to the reference line and pass through the crack, and set the seamless measurement line to be parallel to the equidistant measurement line. Step 5): Based on the reference frame, move the injection device along the equidistant measurement line, observe the cracks on the concrete surface on the display screen and read their widths. Taking the crack boundary on the equidistant measurement line as the starting point, take measurement points with an equal interval of Δw. Start the high-frequency narrow beam focusing probe transducer to acquire the ultrasonic signals at each measurement point, obtain the time history diagram of the reflected wave signal intensity, and calculate the crack boundary depth h at each measurement point. Among them, v i Let t be the speed at which ultrasound propagates in the i-th medium. i Let be the propagation time of the ultrasonic wave in the i-th medium; The crack boundary depth and the plane coordinates of each measurement point obtained by the positioning device are transmitted to the imaging module in real time, and the two-dimensional morphology of the crack in the cross section of the crack is generated by the quadratic spline interpolation method. Step 6): In the imaging module, the two-dimensional crack morphology within the cross-section of each crack is stitched together using a quadrilateral mesh method to form a three-dimensional crack morphology model. This three-dimensional crack morphology model is then displayed on the screen. Simultaneously, the volume of the three-dimensional crack morphology model is calculated in the imaging module and compared with the tracer injection volume to determine the accuracy of the three-dimensional crack morphology model, thereby monitoring the distribution of concrete cracks. use To determine the accuracy of the three-dimensional crack morphology model, if E≤10%, the accuracy of the constructed three-dimensional crack morphology model meets the requirements. Where E is the volume error of the three-dimensional model of the crack morphology, and V m V is the volume of the 3D model. s This refers to the volume of tracer injected.

4. The method for three-dimensional morphological recognition of concrete cracks based on ultrasound according to claim 3, characterized in that: In step 5), the process of generating the two-dimensional morphology of the crack within the crack cross section using quadratic spline interpolation is as follows: The planar coordinates and depths of the measurement points within the crack cross-section are transformed into three-dimensional coordinates (x, y, z). Since the y-coordinates of measurement points on the same measurement line are the same, quadratic spline interpolation is performed using the x and z coordinates. That is, given n data points (x1, z1), ..., (x...) on the same measurement line... n ,z n ), in the interval [x i ,x i+1 Construct a quadratic spline polynomial S in [the context of the original text]. i (x): S i (x)=a i +b i (x-x i )+c i (x-x i ) 2 (2) Interpolation conditions are met: S i (x i )=z i (3) S i (x i+1 )=z i+1 (4) Let the quadratic spline polynomial S i (x) If we maintain continuity, the first derivative remains continuous, and the crack boundary is a natural boundary, then Where S i (x) represents the interval [x] i ,x i+1 The quadratic spline polynomial constructed in ], a i b i c i x is the coefficient. i z i Let S be the x-coordinate and depth of the crack boundary at the i-th measurement point out of n measurement points within the crack cross-section. i (x i+1 ) is the interval [x i ,x i+1 The quadratic spline polynomial in x = x i+1 The value at point S i+1 (x i+1 ) is the interval [x i+1 ,x i+2 The quadratic spline polynomial in ] at the point x = x i+1 The value at point S i '(x i+1 ) is the interval [x i ,x i+1 The quadratic spline polynomial in x = x i+1 The first derivative value at point S i+1 '(x i+1 ) is the interval [x i+1 ,x i+2 The quadratic spline polynomial in x = x i+1 The first derivative at x = x1, S1″(x1) is the value of the second derivative of the quadratic spline polynomial in the interval [x1,x2] at x = x1. n-1 "(x n ) is the interval [x n-1 ,x n The quadratic spline polynomial in x = x n The second derivative value at; The calculated quadratic spline polynomials of the boundary interval and the intermediate interval are the lines connecting adjacent boundary points within the same crack profile. Connecting each boundary point forms the two-dimensional crack morphology within the crack cross section.

5. The method for three-dimensional morphological recognition of concrete cracks based on ultrasound according to claim 4, characterized in that: In step 5), the quadratic spline polynomial on the boundary interval [x1, x2] is calculated as follows: Where x1 is the abscissa of the crack boundary below the first measurement point in the crack cross section, x2 is the abscissa of the crack boundary below the second measurement point in the crack cross section, z1 is the depth of the crack boundary below the first measurement point in the crack cross section, and z2 is the depth of the crack boundary below the second measurement point in the crack cross section.

6. The method for three-dimensional morphological recognition of concrete cracks based on ultrasound according to claim 4, characterized in that: In step 5), the quadratic spline polynomial on the intermediate interval [x2, x3] is obtained as follows: Where x1 is the abscissa of the crack boundary at the first measurement point in the crack cross section, x2 is the abscissa of the crack boundary at the second measurement point in the crack cross section, x3 is the abscissa of the crack boundary at the third measurement point in the crack cross section, z1 is the depth of the crack boundary at the first measurement point in the crack cross section, z2 is the depth of the crack boundary at the second measurement point in the crack cross section, z3 is the depth of the crack boundary at the third measurement point in the crack cross section, and b1 and c1 are the coefficients of the obtained quadratic spline polynomial S1(x).

7. The method for three-dimensional morphological recognition of concrete cracks based on ultrasound according to claim 3, characterized in that: In step 6), the process of using the quadrilateral mesh method to piece together the two-dimensional crack morphology within each crack cross section to form a three-dimensional model of the concrete crack morphology is as follows: Given Y cross-sections of cracks, the coordinates of the boundary points (measurement points) in each cross-section are... Where l is the cross-sectional number of the crack, and m l Let be the number of boundary coordinate points on the l-th crack cross section; first, resample the boundaries of each crack cross section, using the deepest point of each crack cross section as the starting point for resampling: Calculate the cumulative arc length s at the deepest point of each crack cross section. k , Construct the arc length parameter t at the k-th point k ,make Where s1 is the cumulative arc length of the deepest point in the crack cross section, s k Let t be the cumulative arc length at the k-th point. k Let the arc length parameter be the arc length parameter at the k-th point; The coordinates x and z and the arc length parameter t are constructed using quadratic spline interpolation. k The function; That is, by We get x = F(t), and similarly we get z = G(t); Take N equally spaced points on the interval t∈[0,1] to obtain the coordinates of the boundary points of the resampled cross-section. in x j =F(t) j ), z j =G(t) j ), j is the boundary point number of the resampled cross-section, l is the cross-section number of the crack, t j Let x be the parameter coordinates of the j-th point after resampling. j Let z be the x-coordinate of the j-th point after resampling. j This represents the ordinate of the j-th point after resampling; Let the j-th point on the cross section of crack l be ? Coordinates are Corresponding points of adjacent cross sections and Connect the points by quadrilaterals. and Connect them, l∈[1,Y-1]j∈[1,N-1], and splice them to form a three-dimensional crack morphology model.

8. The method for three-dimensional morphological recognition of concrete cracks based on ultrasound according to claim 3, characterized in that: In step 6), when E > 10%, the width, depth and orientation of the crack are re-acquired by reducing the distance between measurement points Δw and the distance between equidistant measurement lines Δy, and a three-dimensional crack morphology model is established until E ≤ 10%.

9. The method for three-dimensional morphological recognition of concrete cracks based on ultrasound according to claim 3, characterized in that: In step 3), the ultrasonic tracer is glycerol, and 0.5-2% by weight of nano-sized alumina powder is added to the glycerol as a scattering enhancer.

10. The method for three-dimensional morphological recognition of concrete cracks based on ultrasound according to claim 3, characterized in that: In step 5), after obtaining the two-dimensional morphology of the crack in a cross-section of a crack, the liquid injection device is moved to the equidistant measurement line Δy to continue measuring the two-dimensional morphology of the crack in the next cross-section of the crack.

Images